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Soldering Surface Mount Components 6
- Thread starter roydm
- Start date
You need some sort of reflow solder and a reflow oven. Robots, or more precisely, pick&place machines, only place the chips on the board that already has solder paste on it. The boards then go through a reflow furnace, which is what actually does the soldering. People have gotten by with a modified IR oven, but you still need the solder paste.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
SMT can be assembled and soldered by hand, but depending upon the component size and the pitch of the IC leads it can require a bit of experience. Good soldering iron and fine tips are a must. A hand-held hot-air pencil is handy. I've worked with contract manufacturers that had skilled assemblers that would do, by hand, a dozen boards with 100 components each in just a few hours as a prototype run ahead of a formal pick-n-place program and solder stencil being made.
Lacking that, well, I have ways I do it that work with experience. A blunt tip, fresh de-solder wick, and good tweezers. Tack an IC down by one lead. Use tweezers to align as you re-heat the lead. Tack the corner pins. Have a go at the middle pins. Then use the de-solder wick to remove all of your mistakes taking care to only remove the majority of the solder with the wick.
Lacking that, well, I have ways I do it that work with experience. A blunt tip, fresh de-solder wick, and good tweezers. Tack an IC down by one lead. Use tweezers to align as you re-heat the lead. Tack the corner pins. Have a go at the middle pins. Then use the de-solder wick to remove all of your mistakes taking care to only remove the majority of the solder with the wick.
MacGyverS2000
Electrical
I regularly hand solder SMT components down to 0201, but I need to use a microscope. No special solder other than eutectic and a quality iron with a fine tip. Flux is typically brought out when there's rework to be done, but the initial pass typically doesn't need it.
Dan - Owner
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Dan - Owner
This morning I had to hand solder two 12LGAs. That's 12 pins underneath a 2mm square package! 0.009" traces on 0.020" centers.
Was a royal pain.
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Roy, I'll solder them for you if it gets to be too big a hassle.
Keith Cress
kcress -
Was a royal pain.
Roy, I'll solder them for you if it gets to be too big a hassle.
Keith Cress
kcress -
Note that hand soldering requires accessible pins; if they're not accessible, then some other approach is required
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
These were not accessible, but I hand soldered them since paste and a high-end hot-air gun just made it hard to find the 12LGAs over and over.
Keith Cress
kcress -
Keith Cress
kcress -
MacGyverS2000
Electrical
Unless it's for power, 98% of the traces I work with are 3-4mils... try tacking a wire to THAT for debug purposes. Spools of thin magnet wire abound around here. Fixing a 4mil via with an annular ring <11mils is also a fun day. Thank God I spend most of my time designing and not fixing.
Dan - Owner
Dan - Owner
E-gads! Even a fine tip soldering iron tip probably looks like a barn door held up to those traces.
Keith Cress
kcress -
Keith Cress
kcress -
MacGyverS2000
Electrical
I don't have the most steady of hands, but our brain does an amazing job with feedback. If someone other than me were to look at my hands under the microscope, I have no doubt they would be wiggling in/out of the field of view at a relatively fast rate... but once I'm looking at them, the visual feedback reduces those jitters to a scale similar to that when seen only with the naked eye. In essence, most can work under the microscope on tiny objects with no more trouble than without one on similarly-scaled larger objects.
I just looked... when zoomed in fully using the scope on my desk, four quad-resistor packs (0804) sitting end to end barely fit the field of view. The scopes on the soldering benches are even high magnification. Our soldering tips are pretty fine, so there's still plenty of viewing area, even with an 0201.
Dan - Owner
I just looked... when zoomed in fully using the scope on my desk, four quad-resistor packs (0804) sitting end to end barely fit the field of view. The scopes on the soldering benches are even high magnification. Our soldering tips are pretty fine, so there's still plenty of viewing area, even with an 0201.
Dan - Owner
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1
- #11
mudandsnow
Electrical
A good iron with a chisel tip, thin solder, good tweezers and good wick can go a long way. Concave tips can be good too for wipe soldering leads on an IC.
If I have a lot to do or any pads that aren't accessible I'll get a stencil from Polulu for about $50, squeegee some solder paste through it, then place components and put it in toaster oven.
Cheap stencils:
Oven that doesn't require mods:
If I have a lot to do or any pads that aren't accessible I'll get a stencil from Polulu for about $50, squeegee some solder paste through it, then place components and put it in toaster oven.
Cheap stencils:
Oven that doesn't require mods:
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1
- #12
pololu for stencils, huh?
Try this place. I've ordered one from here at 3am and had it shipped at 5am. Blew my mind.
ohararp stencils
$25 - Highly recommended.
I get the Kapton ones. They last quite well. I've gotten Kapton ones to do a first few protos and ended up not needing any revs, and gone on to make a couple hundred boards with them.
Keith Cress
kcress -
Try this place. I've ordered one from here at 3am and had it shipped at 5am. Blew my mind.
ohararp stencils
$25 - Highly recommended.
I get the Kapton ones. They last quite well. I've gotten Kapton ones to do a first few protos and ended up not needing any revs, and gone on to make a couple hundred boards with them.
Keith Cress
kcress -
MacGyverS2000
Electrical
mud, you say that oven doesn't require mods... does it have a programmable temp profile? If so, that would be a dream for a reflow oven. I've often considered picking up an IR oven and making a controller, but other projects always seem to take priority.
Dan - Owner
Dan - Owner
Man Dan.. All the toaster ovens I've used for reflow required substantial modding to get them capable of heating fast enough to get near typical profiles. Usually I have to add insulation on all sides and block holes you could march three roaches shoulder-to-shoulder thru.
Keith Cress
kcress -
Keith Cress
kcress -
MacGyverS2000
Electrical
I've come across several decent DIY setups online, generally in the $300 range or so (that includes the oven). Insulation is rule #1. I'm working on a new LED project, and I will likely need something simple like that for quick prototyping. I may just break down and build one using COTS parts.
Dan - Owner
Dan - Owner
mudandsnow
Electrical
Thanks for the recommendation itsmoked. ohararp stencils looks like a good site.
MacGyver, I use an oven similar to the one in the link and change temperature manually about once a minute. A controller and insulation would be a nice addition.
MacGyver, I use an oven similar to the one in the link and change temperature manually about once a minute. A controller and insulation would be a nice addition.
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1
- #17
Thanks M&S. Manual. Yikes.
Dan you can use any old clapped-out toaster oven that is 1400W or so and has top AND bottom elements. You will want one with a single shelf that slides in and out without any herky-jerky. Throw away the rest of the shelves.
You will likely need to hack it to remove all signs of temp control. Wire it up so you plug it in and it heats up.
Then use something like this stuff:
McMaster Carr Semi-rigid insulation
to insulate the top, sides and back. Often the bottom doesn't matter much.
Grab a ramp-and-soak temp controller or use an Automation Direct cheap CLICK PLC with a TC module and a relay of some sort. Cycles are so mellow you can use a mech relay without issues.
You want a small gauge TC too. I use these:
24AWG or smaller Type J or K
You place the TC directly on one of the boards you're reflowing. You put it on a bare pad somewhere so it is measuring the actual board pad temps. You need it coming in from above so you can slide in the shelf with the boards then lift and set down, very much like a phonograph needle, the TC onto the selected board. You want the TC stiff enough to stay but not wrestling-match stiff so when you let go it sweeps across your parts going to where it wants to be.. (Been there.)
Then setting the control profile you typically have some initial long PWM to get the board up to about 80/90C and then dwell there for moisture reduction. Then more aggressive PWMing to get to about 80% of the melting point and once settled there you do a full-on bust-a-gut sprint up to the peak temp in about 30 seconds. (that's where you need the power and low heat loss). Then power down and let the whole thing cool down to just below the freezing point then you need to open the oven door about 30% to get the temp down pretty quick or you roast all your parts and the boards lose their flatness.
A PLC might make the most sense since no normal Ramp-and-soak deals well with the second based times and the fact that the oven will be fire-walled often to make the schedules. You will end up setting the Ramp and Soak to ridiculous values that will be changed before ever reaching them just to get close to the desired profile. A PLC could also open the door for you in a timely manner.. I've not noticed and 'browned' things. A PLC also could BEEP you that the cycle is over since you do NOT want this thing out-gassing in the same room you're in.
Oh OH You definitely want an oven with a see thru glass window as you'll need to watch the process frequently to troubleshoot and tweak.
Keith Cress
kcress -
Dan you can use any old clapped-out toaster oven that is 1400W or so and has top AND bottom elements. You will want one with a single shelf that slides in and out without any herky-jerky. Throw away the rest of the shelves.
You will likely need to hack it to remove all signs of temp control. Wire it up so you plug it in and it heats up.
Then use something like this stuff:
McMaster Carr Semi-rigid insulation
to insulate the top, sides and back. Often the bottom doesn't matter much.
Grab a ramp-and-soak temp controller or use an Automation Direct cheap CLICK PLC with a TC module and a relay of some sort. Cycles are so mellow you can use a mech relay without issues.
You want a small gauge TC too. I use these:
24AWG or smaller Type J or K
You place the TC directly on one of the boards you're reflowing. You put it on a bare pad somewhere so it is measuring the actual board pad temps. You need it coming in from above so you can slide in the shelf with the boards then lift and set down, very much like a phonograph needle, the TC onto the selected board. You want the TC stiff enough to stay but not wrestling-match stiff so when you let go it sweeps across your parts going to where it wants to be.. (Been there.)
Then setting the control profile you typically have some initial long PWM to get the board up to about 80/90C and then dwell there for moisture reduction. Then more aggressive PWMing to get to about 80% of the melting point and once settled there you do a full-on bust-a-gut sprint up to the peak temp in about 30 seconds. (that's where you need the power and low heat loss). Then power down and let the whole thing cool down to just below the freezing point then you need to open the oven door about 30% to get the temp down pretty quick or you roast all your parts and the boards lose their flatness.
A PLC might make the most sense since no normal Ramp-and-soak deals well with the second based times and the fact that the oven will be fire-walled often to make the schedules. You will end up setting the Ramp and Soak to ridiculous values that will be changed before ever reaching them just to get close to the desired profile. A PLC could also open the door for you in a timely manner.. I've not noticed and 'browned' things. A PLC also could BEEP you that the cycle is over since you do NOT want this thing out-gassing in the same room you're in.
Oh OH You definitely want an oven with a see thru glass window as you'll need to watch the process frequently to troubleshoot and tweak.
Keith Cress
kcress -
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1
- #18
MacGyverS2000
Electrical
I think I may try this one at some point... even has a servo to open the door for you.
Dan - Owner
Dan - Owner
I considered that unit but delivery is fairly abysmal so I re-rolled my own.
Keith Cress
kcress -
Keith Cress
kcress -
MacGyverS2000
Electrical
One thing that is somewhat unclear is support for different profiles. A comment or two I read suggested you had to reprogram the entire thing if you want a new profile, and those who used multiple profiles left it connected to a computer. With all of that power/storage, you would think they could have multiple profiles stored.
Dan - Owner
Dan - Owner
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