LowPowerLab Forum
Hardware support => General topics => Topic started by: EloyP on February 01, 2015, 03:37:41 PM
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Hello,
I am pretty frustrated with my first SMT project -- I designed a board, had it made at Seed Studio, and manually soldered all the components (I have a decent Hakko FX-888 soldering iron). Parts of the board works and some other parts don't work. I've soldered a couple of boards and there is always some issue that I need to troubleshoot. The worst part is that I am wasting a lot of time troubleshooting, which prevents me from focusing on the firmware, or to move on to the next project. It's frustrating to not know if a problem is caused by a bad component, a bad PCB, or a cold joint. The same subsystem (a latching solenoid driver) is duplicated four times on this board, and it works on both the breadboard and on other parts of the board, so I think the design is good. I am even having problems tracing with a multimeter signals within the board (sometimes I have continuity and some other times I don't).
I used liquid flux to facilitate soldering of all components and that seems to always make a mess (pads seem to get corroded over time, the board looks dirty, etc.). If the design has problems it is really difficult to diagnose because pads look corroded so it's hard to make good contact with the multimeter. Pads are very small to put there the multimeter probes. I used 603 resistors, SOICs, SOT-23 transistors, etc. Nothing too tiny I guess but it is being difficult for me to solder all these components by hand and have everything working without some serious troubleshooting.
I know there are better ways to finish these boards but I'm not sure which one to choose. I don't mind making a small investment to buy a small toaster over or an electric skillet. Anything to avoid the frustration or getting discouraged from working on my electronic projects (which is currently the case). I do not intend to do mass-produce any boards; I just need to produce a couple of boards of each project for personal use. I don't know why this is being so hard; these boards are not complex; I'm not talking about creating a Raspberry Pi-like board.
I've heard good things about the electric skillet method (https://www.sparkfun.com/tutorials/59)... Should I go this way as my first attempt to do better than the manual method that is causing me so much frustration? Recommendations for a good starter solder paste to use with whatever method you recommend would also be appreciated (bonus points for a Mouser part number as I need to place an order with them soon).
Thanks in advance!
Frustrated,
Eloy Paris.-
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For anything SMD I recommend using solder paste and a stencil, it will be much much faster than hand placement of paste and tweezing the components. I used to make all Moteinos by hand (https://www.youtube.com/watch?v=YhavXauuWqY) by making stencils out of soda cans (http://lowpowerlab.com/blog/2013/02/11/diy-smd-metal-stencils-the-definitive-tutorial/), read those links for more details. These days I have a laser cutter so I etch my stencils out of mylar which is much faster and cleaner etc. But you can also order them from oshstencils but the downside is the wait. The flux is very important for rework, and the ebay and chinese market is full of junk flux and paste just watch this video (https://www.youtube.com/watch?v=tS7NY5qmOiA) of my experiece with solder paste bought from Sparkfun which I believe they now replaced with brand name paste after realizing it was indeed garbage. I recommend a good brand sac205 lead free no-clean solder paste. Keep it refrigerated. Back in manual SMD days I used a small toaster oven that I insulated with tinfoil which made it much better and used a K thermocouple to watch it reflow, that's the best thing before a real reflow oven.
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<..snip> But you can also order them from oshstencils but the downside is the wait.
Felix, would you be willing to provide some insight on what files you recommend sending to oshstencils? They have so many options that it's pretty overwhelming. I know for the etching you shrunk the SMT pads by some fixed amount. Would you do this with these stencil files as well?<..snip> Back in manual SMD days I used a small toaster oven that I insulated with tinfoil which made it much better and used a K thermocouple to watch it reflow, that's the best thing before a real reflow oven.
After watching one of your videos on using a toaster oven I purchased one, fiddled with the timing while measuring the temps, and now have a Moteino (non-wireless) controlled reflow oven! All automatic (except opening the door for the cool down phase). I'm not sure I would have tried this without your sharing your experience.
Thanks!!!
Tom
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For making stencils you have to send the CREAM layer. Every maker has their own spec of how to process that layer before sending (if at all) or they process it for you, so its fab specific. The thickness of the stencil also matters a LOT depending on what you are placing on the board/panel. There are a lot of ins and outs to making a good placement and a good reflow. It's a huge learning experience especially after owning a pick and place machine. It's hard to explain it all in a blog post or here. It's just a matter of practice and observation of what works best. These kinds of things you will probably never find on any blog post or from companies like adafruit or SF regardless how "open" they claim they are. This is more like insider knowledge that will never be shared because it's more like IP and it costs thousands in fabrication/materials and man hours to tweak and develop a process technique and set of parameters that work best. It probably costs a fortune to train someone to understand how this works. Fabrication and assembly are really hard things to master and do well. I am still learning by mistakes. Also notice how adafruit is not really open hardware any more since they became huge haha...
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For making stencils you have to send the CREAM layer. Every maker has their own spec of how to process that layer before sending (if at all) or they process it for you, so its fab specific. The thickness of the stencil also matters a LOT depending on what you are placing on the board/panel. There are a lot of ins and outs to making a good placement and a good reflow. It's a huge learning experience especially after owning a pick and place machine. It's hard to explain it all in a blog post or here. It's just a matter of practice and observation of what works best. These kinds of things you will probably never find on any blog post or from companies like adafruit or SF regardless how "open" they claim they are. This is more like insider knowledge that will never be shared because it's more like IP and it costs thousands in fabrication/materials and man hours to tweak and develop a process technique and set of parameters that work best. It probably costs a fortune to train someone to understand how this works. Fabrication and assembly are really hard things to master and do well. I am still learning by mistakes. Also notice how adafruit is not really open hardware any more since they became huge haha...
Thanks Felix, this is helpful. I'll look at the stencil maker's website to see if they have a DRC/post processor like Seeed has. I should have done this in the first place... :-[
Tom
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I think your best bet is oshstencils, its cheap and probably pretty fast and I'm sure they know how to deal with edge case stencils apertures. But I'd check their rules to be sure you're getting what you expect.
And I meant to say congrats for making a Moteino controlled reflow oven, I've never taken it that far, I'm such a dork not using my own hardware to pimp my toaster oven. But these days I very rarely use it, only for prototypes, all production boards get reflowed in the conveyor oven, pop in and pop out, perfect reflow, no stress.
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I think your best bet is oshstencils, its cheap and probably pretty fast and I'm sure they know how to deal with edge case stencils apertures. But I'd check their rules to be sure you're getting what you expect.
And I meant to say congrats for making a Moteino controlled reflow oven, I've never taken it that far, I'm such a dork not using my own hardware to pimp my toaster oven. But these days I very rarely use it, only for prototypes, all production boards get reflowed in the conveyor oven, pop in and pop out, perfect reflow, no stress.
Thanks Felix, I've re-read their website and didn't see any DRC but did indicate which files they need so I'll give it a shot.
The reflow oven came out very well, thanks you your tips about when to turn off the element. The controller was very easy to build on a perf board and I hacked the SSR into the heating element wiring so that the rest of controls still work. I used a MAX31855 Thermocouple module with a K type probe and that works very well. I've attached the temp profile I'm getting with it. Good enough for anything I'm going to throw at it.
I've been doing hand pasting and it's come out ok, but had some issues around Christmas time trying to solder some 14 pin LGAs (ADXL345 accelerometer). Uh, I had to do three passes to get one of two boards working - not very good. I'm hoping stencils will allow me to do this kind of work.
We'll see. Thanks again.
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For anything SMD I recommend using solder paste and a stencil, it will be much much faster than hand placement of paste and tweezing the components. I used to make all Moteinos by hand (https://www.youtube.com/watch?v=YhavXauuWqY) by making stencils out of soda cans (http://lowpowerlab.com/blog/2013/02/11/diy-smd-metal-stencils-the-definitive-tutorial/), read those links for more details. These days I have a laser cutter so I etch my stencils out of mylar which is much faster and cleaner etc. But you can also order them from oshstencils but the downside is the wait. The flux is very important for rework, and the ebay and chinese market is full of junk flux and paste just watch this video (https://www.youtube.com/watch?v=tS7NY5qmOiA) of my experiece with solder paste bought from Sparkfun which I believe they now replaced with brand name paste after realizing it was indeed garbage. I recommend a good brand sac205 lead free no-clean solder paste. Keep it refrigerated. Back in manual SMD days I used a small toaster oven that I insulated with tinfoil which made it much better and used a K thermocouple to watch it reflow, that's the best thing before a real reflow oven.
Thanks Felix. Right now I am not too concerned about using a toothpick or syringe to apply the solder paste -- I just need to assemble for personal use a handful of boards of each project I make. Not sure it's worth to create my own stencils (or have them made) when I will only assemble a couple of boards. But I do see the benefit of using stencil when one has to assemble more than a handful of boards.
At this point in my journey into SMT I am more concerned about how to solder components once solder has been applied and components been placed. You mention a small toaster over. Would you recommend that over the electric skillet method described in that Sparkfun tutorial? And on a related note, is there some open source project I can use for controlling the reflow process using a toaster over?
Thanks again.
Cheers,
Eloy Paris.-
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how to solder components once solder has been applied and components been placed .. ?
I think you mean reflow phase, just get a cheap toaster oven and insulate it with tinfoil and kapton tape. It's much better than a skillet.
There are countless tutorials online how to do the different phases of SMT and how different people do it different ways.
Also many open source control methods. I haven't used any, I just sat there for a few minutes every time I reflowed, thinking to myself I am such a dork wasting my time looking at a temperature reading, glad that phase is over now. If making your own stencils is not worth it for you then making a reflow oven controller is much less so.
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how to solder components once solder has been applied and components been placed .. ?
I think you mean reflow phase, just get a cheap toaster oven and insulate it with tinfoil and kapton tape. It's much better than a skillet.
There are countless tutorials online how to do the different phases of SMT and how different people do it different ways.
Also many open source control methods. I haven't used any, I just sat there for a few minutes every time I reflowed, thinking to myself I am such a dork wasting my time looking at a temperature reading, glad that phase is over now. If making your own stencils is not worth it for you then making a reflow oven controller is much less so.
Yes, sorry, I meant the reflow phase.
Not sure I understand your comment that if making my own stencils is not worth it for me then making a reflow over controller is much less so. Unless you are talking about the *controller* and not the oven itself? I mean, I still have to solder my boards (small quantities, just for personal use, at least for now) and hand-soldering is not cutting it (perhaps I am lacking skill, but the bottom line is that I seem to damage components, create cold joints, etc.). This is why I'm looking into another solution (oven or skillet). Just wanted to know if you meant that the over (not the controller) is not worth it if I will not be using stencils ;-)
In any case, if going the toaster oven route, is the temperature reading a must? Can I just not watch through the over window when the solder reflows? Apologies for the dumb questions but I am so new to this!
Cheers,
Eloy Paris.-
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If you have to ask .. do it in this order :)
1. Put it in toaster oven and watch for solder to reflow, then count to 10 and stop/open door and blow air gently on the boards to cool them down.
2. Use a ktype thermocouple with a multimeter (this is what I did) and watch the temperature rise, stop the oven after soak zone, then once temperature stabilizes start it again and watch it raise towards reflow zone, stop it before it reaches that and oven should still heat up to allow reflow. This takes practice.
3. Get fancy and buy a reflow oven controller.
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If you have to ask .. do it in this order :)
1. Put it in toaster oven and watch for solder to reflow, then count to 10 and stop/open door and blow air gently on the boards to cool them down.
2. Use a ktype thermocouple with a multimeter (this is what I did) and watch the temperature rise, stop the oven after soak zone, then once temperature stabilizes start it again and watch it raise towards reflow zone, stop it before it reaches that and oven should still heat up to allow reflow. This takes practice.
3. Get fancy and buy a reflow oven controller.
Haha, okay, that works. I'll give the toaster over a try then. Okay to assume that pretty much any oven I can find at Target or Walmart will do?
Cheers,
Eloy Paris.-
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Probably, look for one that looks easy to insert/remove the tray. If you can find one with 4 elements that's even better (more even heating). But even the cheapest should be ok.
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Fun thread! I never heard about OSH stencils before, wow they are cheap!
Also just found this and wanted to share: DIY Manual Pick and Place machine (http://vpapanik.blogspot.gr/2012/11/low-budget-manual-pick-place.html). Fascinating!
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I was fascinated about that machine also until I realized anything in between hand placement with a nozzle tool and a real pick and place is too expensive/too slow/hopeless/useless.
I settled on the reversed aquarium pump + syringe & bended needle method (https://lowpowerlab.com/blog/2013/04/02/diy-manual-smd-pick-and-place-machine-for-20/) which is cheap and the fastest you will ever get with hand placement, I can guarantee that.
Read this post (http://lowpowerlab.com/blog/2014/05/19/pick-and-place-entry-level-options/) which explains why this machine you included is not something I ended up using. The ONLY advantage of that machine is placing on very large PCBs which are hard to reach in the middle with a stable hand. Also looking away from the PCB to a monitor for placement of a component will make it about 10X slower than it already is, it's essential that your eye is looking at your hand when placing manually, and not away to a monitor.
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I settled on the reversed aquarium pump + syringe & bended needle method (https://lowpowerlab.com/blog/2013/04/02/diy-manual-smd-pick-and-place-machine-for-20/) which is cheap and the fastest you will ever get with hand placement, I can guarantee that.
Felix, I saw your blog on this (I LOVED the discovery of reversing the valve! EXCELLENT!) and explored it but didn't find a source for bent needles. I did find lots of straight ones in all kinds of sizes. Where did you get yours and what size/gauge is it?
Tom
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Bent by me :)
Just take a thicker needle, saw it down to about 1/2-3/4" length and then bend it gently to avoid it collapsing/creasing.
And by the way since I wrote that post I found (others did it) that the valve is very easy to reverse instead of making a hole and rerouting the output (the way I originally did it). Just flip the valve in the pump and now the output pump nozzle will suck air instead of push air (ie vacuum).
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Tom,
You can send us 2 file formats. Either A) An Eagle .brd file or B) A RS274-X Gerber file. Board outlines are not required, but are recommended for visual reference of how big your stencil will be. You should send us your cream/paste layer (some EDA software calls it paste, some call it cream, it's the same thing).
In most cases using our 3mil product, with the standard shrink amount for your EDA software is recommended.
If you have any additional questions, don't hesitate to email us.
-Brent
<..snip> But you can also order them from oshstencils but the downside is the wait.
Felix, would you be willing to provide some insight on what files you recommend sending to oshstencils? They have so many options that it's pretty overwhelming. I know for the etching you shrunk the SMT pads by some fixed amount. Would you do this with these stencil files as well?<..snip> Back in manual SMD days I used a small toaster oven that I insulated with tinfoil which made it much better and used a K thermocouple to watch it reflow, that's the best thing before a real reflow oven.
After watching one of your videos on using a toaster oven I purchased one, fiddled with the timing while measuring the temps, and now have a Moteino (non-wireless) controlled reflow oven! All automatic (except opening the door for the cool down phase). I'm not sure I would have tried this without your sharing your experience.
Thanks!!!
Tom
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I hand apply and use a toaster oven with a Pi. Works fine with a steady hand.
http://www.cupidcontrols.com/2013/12/home-reflow-soldering-on-a-budget/
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Tom,
You can send us 2 file formats. Either A) An Eagle .brd file or B) A RS274-X Gerber file. Board outlines are not required, but are recommended for visual reference of how big your stencil will be. You should send us your cream/paste layer (some EDA software calls it paste, some call it cream, it's the same thing).
In most cases using our 3mil product, with the standard shrink amount for your EDA software is recommended.
If you have any additional questions, don't hesitate to email us.
-Brent
<snip...>
Wow! What service! Answering my question on our forum! :)
I use Eagle so no problem there, but I do have a question: If I send a .brd file, does your ordering system understand if there are only SMT devices on a single layer or will it want to charge me for two stencils anyway? A related question (since this does occur on one of my boards), if I have SMT devices on both layers but only want a stencil for one of them (bottom layer is just a few large caps - easy to hand solder these), is that possible?
I have a new board going out in a couple of days. I'll get a stencil from you as well.
Thanks!
Tom
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Wow! What service! Answering my question on our forum! :)
Indeed, pleasant surprise. OSHPark and OSHStencils are providing a very valuable service to the electronics enthusiasts and maker community and to all those that just need a quality and prototype from a dependable service.
I use OSHPark all the time for my prototypes. Haven't tried OSHstencils since I etch my stencils on my laser machine from mylar but I saw some first hand. I did notice the OSHstencils are kapton that come from a roll which leaves them curvy, almost cylindrical , so they probably need to be framed to be kept flat, otherwise it might be difficult to apply the paste especially with larger PCBs, I'm sure they have some guidelines around that, but otherwise very nicely etched apertures and resolution.
Also 3 mil might be a little thin for some components like USB connectors or large footprints, but again this is prototyping, as long as there is a bond it's good to go.
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A curved stencil might be a problem unless the concave side is up where the curve would help press the stencil against the PCB...
The good news is that I'm not smart enough (any more) to design any "larger PCBs" ;)
Tom
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A curved stencil might be a problem unless the concave side is up where the curve would help press the stencil against the PCB...
The good news is that I'm not smart enough (any more) to design any "larger PCBs" ;)
I think everyone who got used to Eagle designs boards smaller than 80x100mm which is plenty for most things. I think designing small and efficient takes more smarts (and time!) than throwing components in a large area and calling it a day.
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Tom (and Felix),
If you upload the .brd file, we will extract out the tCream and bCream layers automatically and display them. Then there is an option to ignore a layer, so if you don't have components on the bottom side, just set it to "Not Used" and it'll only produce renderings of the top side, and thus you can order just that one side.
Felix: As for the stencils "rolling", yes that's true, our film does come on rolls, however we're about to make an announcement about that next week :) I've been working with our manufacturer for 6 months to produce a process that they are no longer on rolls and are completely flat. We've ordered our first production run of the material in flat form, and it should be here at the end of next week. We'll release a more formal announcement about it once the material arrives and we've validated that the material integrity has not changed with the new manufacturing process. That said, you can just counter-roll our film with your hand and it'll lay fairly flat, and for most projects just taping a second side does the job nicely.
Let me know if you have any additional questions, and thanks for considering us for your stencil needs. More announcements are coming this quarter too... stay tuned!
-Brent
Tom,
You can send us 2 file formats. Either A) An Eagle .brd file or B) A RS274-X Gerber file. Board outlines are not required, but are recommended for visual reference of how big your stencil will be. You should send us your cream/paste layer (some EDA software calls it paste, some call it cream, it's the same thing).
In most cases using our 3mil product, with the standard shrink amount for your EDA software is recommended.
If you have any additional questions, don't hesitate to email us.
-Brent
<snip...>
Wow! What service! Answering my question on our forum! :)
I use Eagle so no problem there, but I do have a question: If I send a .brd file, does your ordering system understand if there are only SMT devices on a single layer or will it want to charge me for two stencils anyway? A related question (since this does occur on one of my boards), if I have SMT devices on both layers but only want a stencil for one of them (bottom layer is just a few large caps - easy to hand solder these), is that possible?
I have a new board going out in a couple of days. I'll get a stencil from you as well.
Thanks!
Tom
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@OSHStencils, thanks again for the reply. This is perfect, thank you! I'll be sending my board in soon.
Tom
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I've received my first stencil from OSHstencils. FAST turnaround! I sent it in in the morning and it was mailed that evening! As Felix warned, there is a bit of curl in the stencil but it should be fine. Now if I only had the PCBs to try it out! (I JUST hit the Chinese New Year window :( sigh...
They even included a solder paste spreader with the order - kinda looks like the room key from the last hotel I stayed in and 'forgot' to return... 8)
Tom
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I am not sure why OSHStencils would not use mylar instead of kapton. I used mylar to laser etch stencils with excellent results. Maybe they experimented more and it's better for extreme fine pitch because of the heat won't create rings around the fine apertures. But for most other 0.5mm+ pitch i think mylar is great as long as the laser settings are tuned right.
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I FINALLY got a chance to use the stencil I received from OSHStencils as it took 4 1/2 weeks to get my board from Seeeds...
Bearing mind that I haven't used a stencil before, I found that using this stencil made all the difference in the world in getting a nice even paste on the pads. This particular board wasn't all that challenging. It was mostly SOT23, a couple of SOT323, and then a few large ones, a JST connector, and a bunch of 805 resistors & a few 1206 LEDs.
The curl Felix mentioned was annoying, but relatively easy to deal with because the PCB was small. It would have been a royal PITA if it was a larger board. I also purchased a set of 1/16" ell guides from OSH stencil and this turned out to be a wise decision.
I set the guides on my paper cutter's board (nice and square, flat, and stable), taped the stencil to the top most guide and pasted my first board. The paste thickness seemed uniform and, after reflowing, the SOT packages and JST connector were soldered to perfection. The resistors, on the other hand, were soldered reliably but it seemed as if they had too much solder - odd.
All in all, as my first stencilling experience, I'd say it was successful and certain will pay off the next time I do a TQFP or DFN chip.
Tom
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Hello,
Thanks to all for all the thoughts and suggestions on this topic. Since my original post here I've made what I consider to be great progress in my SMT soldering capabilities at a hobbyist level. I plan to do a writeup on my experiences but I wanted to summarize what I've done based on recommendations received here and what I've read elsewhere -- I modified a toaster oven and added to it a reflow oven controller that I bought, I bought some solder paste, applied it with a toothpick, and assembled an Arduino shield-sized board that I had designed a couple of years ago (SOT-23s, 603s, SOICs). Everything worked right out of the oven; the result was fantastic -- shiny joints without the mess of solder flux everywhere, unlike the manual soldering method I had tried previously. I can't wait to try a solder stencil in the future but for assembling a couple of boards applying solder paste with a toothpick was not too bad for me and the results were very good.
All in all, after this experience, I draw two conclusions:
1. With the right tools (e.g. a small reflow oven, good solder paste, good soldering iron, etc.) SMT soldering is really easier than through-hole soldering, even for a hobbyist. It's hard to believe but now I'm convinced it's true.
2. My manual soldering SMT skills do not seem to be as bad as I thought they were -- my initial failures seem to have caused by the Kester flux that I used and my failure to properly clean the flux residue after I was done with manual soldering. This caused severe corrosion of traces, which in turn produced malfunctioning circuits that were really hard to troubleshoot, i.e. is it software? DoA components? components damaged during manual soldering? incorrect design?, etc. Had I cleaned the boards to remove the flux residue I think my circuits would have worked just fine.
Thanks again for all the suggestions. I'll try to do a more detailed writeup about my experiences soon.
Cheers,
Eloy Paris.-
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The Dangerous Prototypes guy did this youtube comparing different fluxes:
He makes it seem as though with a good quality PCB and with a high quality flux, the solder almost automatically flows right where you want it to go.
The flux he appears to love the most is this one: http://www.newark.com/edsyn/fl22/flux-soldering-syringe-5ml/dp/35M3870?ost=EDSYN+%09FL22++FLUX
which, in addition, claims to be a "No Clean" flux.
In contrast, he thinks the Kester flux he tested was "worthless."
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Hi WhiteHare,
The Dangerous Prototypes guy did this youtube comparing different fluxes:
He makes it seem as though with a good quality PCB and with a high quality flux, the solder almost automatically flows right where you want it to go.
The flux he appears to love the most is this one: http://www.newark.com/edsyn/fl22/flux-soldering-syringe-5ml/dp/35M3870?ost=EDSYN+%09FL22++FLUX
which, in addition, claims to be a "No Clean" flux.
In contrast, he thinks the Kester flux he tested was "worthless."
Thanks for sharing. I monitor daily the Dangerous Prototypes posts but sometimes I'm too busy and can't read everything. I had not seen this particular video.
When I used the Kester flux I thought it was fantastic in terms of helping with the manual soldering process -- I really could notice how solder flowed more easily. The problem came later when everything started to corrode. Perhaps it was me that did not do any cleaning. However, the data sheet says it is Ph-neutral and "no clean" so how would have I known that I was supposed to clean the thing very thoroughly?
Cheers,
Eloy Paris.-
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Looking at the datsheet for FL-22, it says:
"Flux residues, which hardly occur when FL 22
FLUTSCHI is carefully applied, usually do not affect
the soldering joint.
Practise has shown that using this flux with its low
solids content usually eliminates the need for washing
the soldered circuit board."
"Usually" is a rather vague. I guess either experience with it tells you whether it needs washing, or else you wash flux off regardless as a precaution just to be sure.
Is there a flux that's absolutely, positively, "no cleaning" required? Or is it a unicorn?
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I've used the kester pen style liquid flux for hand SMD soldering, it's convenient and it works great. But it requires cleaning.
For the panels I assemble I use a paste that has no clean flux and as you can see from Moteinos and other things I make there is very little flux solids residue left behind. That's why it's branded as no-clean. For general purpose soldering most fluxes will work but usually require some cleaning because when you apply it freely you tend to over use. Most solder wire has a flux core also that should be good enough for soldering through hole and even smd.
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I'm not sure if this has been mentioned before, but Beta Layout in Ireland do a low cost reflow kit. Interestingly the oven is available separately for only EUR138, but the V2 profile controller costs EUR119 - scope there for a DIY controller I think ;) Also their PCB-POOL service supply free stensils with protoype PCBs. The PCBs are not bad either.
http://dangerousprototypes.com/forum/viewtopic.php?f=2&t=4471
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Yesterday i soldered 86 smt components & they look perfect 8)
My secret weapon is LOC-TITE thread lock, i placed each resistor 0403 and put a small drop of loc-tite on the side gluing to the board while using my hair dryer to speed things up.
The thread lock glue i used requires +280°C for removal.
I did not use solder paste ;)
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I'm about to go through some hand building of some prototypes, this idea of using thread lock to hold components down is a very interesting one. Usually I tack one end, solder the other and finally dab with no-clean flux and quickly reflow both ends to clean up both joints. This gives a very clean result but is fiddly, especially when tacking the first pad down as it requires holding the component in place while doing it. I'll give the thread lock a go.
Mark.
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For hand soldering, I've found that if I pre-solder one pad before applying the part, then afterward I can position and hold the part down with tweezers (with one hand) and then use a solder pencil (with the other hand) to re=melt the solder on the pad just enough to tack it. It's best to flux the part before remelting the pad.
Previously I used a trace amount of superglue to hold a part in place. It does give a little repositioning time and sets pretty fast.
0403 is awfully tiny though.
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A toothpick dab of solder paste works well. Place the dab on one pad, the device next and hold it down with the other end of the toothpick, and toouch the soldering iron tip to the bit of paste sticking out from the device. Solders immediately and, if you don't jiggle, you've got one end solidly soldered. Dab the other end and repeat.
Tom
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A toothpick dab of solder paste works well. Place the dab on one pad, the device next and hold it down with the other end of the toothpick, and toouch the soldering iron tip to the bit of paste sticking out from the device. Solders immediately and, if you don't jiggle, you've got one end solidly soldered. Dab the other end and repeat.
Tom
That sounds like the best way of all! Thanks for sharing that.
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My way i can place the components on many boards & have both hands
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My way i can place the components on many boards & have both hands
You may in some sense have both hands, but after placement won't you be then be using those same hands to do the soldering? i.e. How is your method better than the method Tom uses?
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I only use my method when I have the occasional SMT component to mount, eg a 'tuned' component or a board which only has a few SMT parts. If I had 'many boards' or 'several SMT components', I'll use a stencil, paste, and my handy dandy reflow 'toaster' oven, which, over time, has become a reliable means to make boards with components down to 0.5mm pitch (eg AM18x5 RTC and various DOF sensors).
Tom
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There is no jiggle or wiggle :P
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Before getting a pick and place I have assembled countless SMD-only boards BY HAND, never used any glue. Glue is only needed when you do double side mounting.
Reflow will pull the parts in place as long as your stencil is made right.
This is how I used to do it:
This is how I used to make my stencils:
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That was awe inspiring 8)
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Back when SMT was new, we used a Fry Daddy for reflow work. We used pre-formed solder pads & a thermocouple for temp monitoring. Once the board was complete a isopropyl wash followed by a distilled water wash. If necessary a light brushing could be helpful. These parts were then fully tested & qualified for Class "S" useage (Space Vehicles) including visual & electrical inspections etc. Later we switched to proper reflow stations, but we had a low budget to start & built most of the process equipment ourselves. Nice to see our work is still being used today!
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Back when SMT was new, we used a Fry Daddy for reflow work.
You dip it in a good buttermilk batter beforehand and it might be tasty and crispy!
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Any recommendations for a specific brand of solder paste for a newbie? First time. Plan on using a stencil from oshstencils. What determines the thickness of the stencil I should use?
Thanks
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Any recommendations for a specific brand of solder paste for a newbie?
Chip Quik is a decent brand and easy to purchase in the US. Don't buy 'bargain' brand, it's not worth the risk of getting old paste. For casual, hobbyist soldering, T3 'NoClean' type is a good choice.
First time. Plan on using a stencil from oshstencils. What determines the thickness of the stencil I should use?
Thanks
Assuming you're not using any 0.5mm pitch devices, the 3mil Polyimide is fine for most applications.
Tom
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Assuming you're not using any 0.5mm pitch devices, the 3mil Polyimide is fine for most applications.
Is the 4mil stainless steel to thick or just not needed?
Thanks
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Is the 4mil stainless steel to thick or just not needed?
Thanks
4mil stainless steel is, first of all, twice the price of polyimide and unnecessary for most hobbyist applications. If you want to use it, however, it will be fine.
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Professionally the thinnest one I would use is 10mil. I use different thicknesses depending on what components are populated, up to 15mil.
The soda can aluminum is perfect thickness for hobby use and I made thousands of Moteinos and other boards with a single stencil, I am not kidding.
If you want to have a bunch of learning fun making one, see my video below, (already posted in this thread before but ... ):
I also have another video that shows how I currently make stencils on my laser cutter, they don't last but they are great for prototypes:
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Im interested in a good guide for the re flow process that includes the science, but for newbies.
Any links?
Besides for google! ;D
@Felix
How about a like button or thank you button for the forum. I think people appreciate being thanked for their advice but I dont think you need a million thank yous on the forums...
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@Felix
How about a like button or thank you button for the forum. I think people appreciate being thanked for their advice but I dont think you need a million thank yous on the forums...
It's allright, not seeking recognition, just ACKing that my stuff is helpful and it works is pretty good feedback :)
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Is there any place i could get for cheap garbage boards that i could practice smt soldering? Something suitable for common resistors.
Or does anyone have junk boards they could give away for cheap?
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I suggest you skip the practice and just dive in with real boards. You'll pick it up in no time.
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Is there any place i could get for cheap garbage boards that i could practice smt soldering? Something suitable for common resistors.
Or does anyone have junk boards they could give away for cheap?
I've seen kits that are specifically SMT training kits - essentially what you suggested, pad layouts for various sized resistors (which cost approximately $0.00000001 ea). If you search for SMT soldering kit you might find something.
I've got some obsolete PCBs laying around, but nothing large, I'll look around and see if any of them would be useful - do you want to learn hand soldering or reflow soldering?
Felix must have a TON of obsolete boards! He can probably sell you whole sheets of them!
Tom
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Im looking to learn reflow soldering. I cant find anything cheap in the usa. I dont have patience to wait for China.
Hand soldering i could get by, but not the proper way.I usually end up with a cold joint. I know im supposed to touch the solder to the joint and not the iron but it just doesn't melt/flow . For my hobbyist projects it works. Any ideas what I'm doing wrong? Ill try to post a clip later..
I guess lets see if Felix chimes in...
Thanks Tom
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The best thing you can do with hand soldering is invest in a good iron and tip. You'll need a combination that heats up quickly, and more importantly can transfer the heat into the component quickly. A lot of budget irons and tips are not worth it IMO.
I did a lot of research into soldering irons and tips, and the best combination I found that gives excellent performance for a reasonable price was a Hakko FX-888D with a T18-S4 tip (the tip is good for general purpose and fine pitch SMD as it has a sharp tip and has a short stubby conical shape, that allows the angle of the soldering iron is used at to apply different surface areas of the tip to the component as needed, and the short cone size allows the heat to transfer faster into the component). The FX-888D will set you back about $100 and the tips around $6 each but it'll be worth it. Also it's worth doing a lot of reading of reviews before buying anything like this.
Mark.
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The web is your friend, I did some videos on SMT stuff, mostly when I used to do everything by hand, you can learn a lot from those, lots of tools and materials available from different vendors. Youtube is amazing at teaching you everything you need to know. I recommend not being cheap when buying tools/materials. You get what you pay for is very true in this business.
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I played around a bit, doesn't sound so complicated as it sounds.
Im wondering if there is a profile that could be used to use reflow soldering to solder in plastic headers? I played around a bit with partial success, meaning the headers melted a bit but still usable. Im using a toaster on broil, so the heat is coming from on top. Im wondering if the plastic takes longer to melt, so If the right speed and temp is figured maybe it can be done. My toaster takes a long time to heat up even though I wrapped it in insulation.
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Headers I would solder by hand. Maybe a heat gun would work on headers if you want to use paste, I've never tried that particular technique but now you've got me curious. The Hakko FX-888D perkey referred to is very nice and reasonable for $100. I bought a Aoyue 968A hot air rework station specifically for the heat gun, believe it was around $175 at the time. It is not as good as the Hakko but the least expensive Hakko heat gun I could find (FR810B-05) is currently going for $850 on Amazon and that was a bit much to justify on a hobby that I seem to have less and less time for. I reflow using the hot plate/frying pan technique, very low tech but it's working for me.
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I also have another video that shows how I currently make stencils on my laser cutter, they don't last but they are great for prototypes:
Felix, I tried your Laser Engraving technique and, while I have some minor tweaking to do, the resulting stencil is certainly usable for 0.65mm pitch devices. Thanks for the tip!
Tom
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Great first try!
It takes me a few minutes to tweak the laser settings every time I etch stencils.
I have a ballpark of the speed, power and other settings like step size etc. Then I usually play with speed and power depending on the detail of the apertures.
Once I etch some sample pads to the quality I want I submit the complete job.
It can take a good 30 minutes for instance to etch a large panel stencil. I usually do this when I get a new design which I consider alpha stage and for a few application this will work just fine. Then I make stainless stencils when I feel the panels require no other changes.
So if I can do that, anyone can easily etch small stencils to very fine pitch/detail, just a little patience and practice is required.
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For manual soldering standard headers what size solder should I be using?
Thanks
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For manual soldering standard headers what size solder should I be using?
Thanks
031 is a good all around solder. Kester is a good brand.
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Does this solder look good for general purpose solder for a newbie?
https://www.amazon.com/gp/product/B00068IJOU/ref=od_aui_detailpages00?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B00068IJOU/ref=od_aui_detailpages00?ie=UTF8&psc=1)
Thanks
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Does this solder look good for general purpose solder for a newbie?
https://www.amazon.com/gp/product/B00068IJOU/ref=od_aui_detailpages00?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B00068IJOU/ref=od_aui_detailpages00?ie=UTF8&psc=1)
Thanks
PERFECT!
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Didn't realize originally, but that solder is leaded. I rather not use leaded solder (due to health risks). I looked again and I cant find kester lead free solder reasonably priced. I found this solder on amazonhttps://www.amazon.com/gp/product/B01LSJ7FWW/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B01LSJ7FWW/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1) Mudder is the brand name. Have you ever heard of that name?
What other brands are "brand names"?
Thanks
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With reasonable ventilation in a room the risks of a hobbyist using leaded solder are very small IMO. The main danger doesn't actually appear to come from the lead either, it's the vapourized rosin. So rosin free, no-clean leaded solder is pretty safe. Remember lead free also melts at a higher temperature than leaded, which ironically can make things worse for rosin especially in a more confined space and will certainly make soldering more difficult.
https://diamondenv.wordpress.com/2011/01/06/lead-exposure-during-soldering/
Mark.
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With reasonable ventilation in a room the risks of a hobbyist using leaded solder are very small IMO. The main danger doesn't actually appear to come from the lead either, it's the vapourized rosin. So rosin free, no-clean leaded solder is pretty safe. Remember lead free also melts at a higher temperature than leaded, which ironically can make things worse for rosin especially in a more confined space and will certainly make soldering more difficult.
https://diamondenv.wordpress.com/2011/01/06/lead-exposure-during-soldering/
Mark.
Very interesting!
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I tried my first SMT reflow soldering... The solder came out grayish dull, doing the reflow is was shiny metal. What does that mean?
Thanks
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Looking at at a bare PCB how can one identify quality manufacturing vs poor? What are things to look for in regards to quality?
Thanks
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Several things I look for:
1 ) Drill registration. Look for the via holes being central to the via pad and hole.
2 ) Hole sizes are finished holes sizes, what you expect and accurately aligned.
2 ) Consistent etching. Look for good clean etch edges on traces and accurate widths.
3 ) Over-etching on corners. Check there are no over-etched corners or angles.
4 ) Uniform thickness of PCB and within expected tolerance.
5 ) Silk screen alignment. Check no silk screen on pads due to mis-alignment and is readable.
6 ) Reworking. Try removing and replacing components a few times to see if the heat reduces the glue strength for pads.
7 ) ATE tested PCBs. Order pre-tested PCBs, usually they use flying probes to check connectivity against the gerbers.
8 ) Wetting. Make sure the pads can accept solder easily.
Finally do a power-ground short test with a multimeter. Check each power supply signal on the PCB is not shorted to any other power supply signal or ground, the last thing you need after fully assembling a PCB is a power short because you'll have no idea whether it's a component or the PCB at fault.
Mark.