Soldering Surface Mount Devices at Home

Martin_H

In the past I've watched a few YouTube videos on soldering boards with SMD components (http://www.youtube.com/watch?v=3NN7UGWYmBY&feature=related). It looked interesting and less impossible than I thought. So tonight I took the plunge and soldered a board with a couple of SMD resistors on it, as well as some through hole components. Afterwards I tested the board and the resisters resisted as expected, so they were installed correctly. While pretty trivial compared to a big SMD project, everything starts with small steps. My observations:

Even in their packaging these resistors are tiny!

Their markings are hard to read even with a magnifying glass and good light.

Moving some that small into position isn't easy.

The actual soldering was easy once it was in position.

Anyone else doing SMD at home?

Phil Pilgrim (PhiPi)

I use solder paste from a syringe and an infrared toaster oven. Fine-tipped, non-magnetic tweezers are a must for positioning parts.

-Phil

Leon

I use a Metcal system with an appropriate cartridge, and a stereo microscope for the difficult stuff. I drag-solder QFP parts using a mini-hoof cartridge and plenty of jelly flux.

WBA Consulting

I still haven't gotten around to fully documenting the process, but my Power Twigs are built at home using Toaster Oven Reflow.

IRobot2

I use solder paste and usually have a stencil cut. Then I use a skillet/hot plate to correctly bring the boards temperature up and take a hot air pen to finish the job. Doing this allowed me to more accurately control the temp on certain areas of the board while leaving others cooler.

RobotWorkshop

I just use my regular Weller soldering iron to do the job. It's all in the technique! Toward the end of the post below there are some instructions I wrote on how to assemble a BS2p40 module using one of the Parallax OEM chips. All the examples were assembled at home. Keep some solder wick on hand for parts like the processor to remove any excess solder.

http://forums.parallax.com/showthread.php?114299-Carrier-PCB-for-OEM-BS2p40-Stamp-chip.&highlight=bs2p40

Robert

Humanoido

Good to hear some people having better luck than me. I was surprised to see a number appear on the resistor soldered to the Parallax Propeller Proto Board when viewing a microscope photo. A microscope is the only way I can see these things. So my toaster oven makes toast, and the skillet is for omlets, paste is for gluing stuff, and the last time I tried to position the SMD, I flinched and it was flicked across the room never to be seen again!

User Name

Many moons ago I soldered for Hewlett Packard. As you might imagine, they were pretty exacting in their standards. Much more recently, when an employer needed some engineering prototypes reworked, he asked me to do it. Privately, I figured it was ridiculous but I gave it the old college try. The results were far better than expected. Like RobotWorkshop points out, there are some techniques to it. Having said that, I'm sure that there exists an IC pitch sufficiently fine that no soldering iron technique would suffice. But the current Propeller certainly isn't there. I've soldered considerably finer pitches than that with an iron.

In an odd way it is reminiscent of modern lithography: We are putting features on silicon that are considerably smaller than the wavelength of the light used to expose the photoresist. My soldering iron, as fine-tipped as it is, still straddles several IC leads. Neverthless they can be soldered with this iron without creating solder bridges. You never know what obstacles you can surmount until you try.

$WMc%

I use a modified PVC welder to solder SMD's with solder paste.
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A PVC welder uses hot-air to weld PVC.Its perfect for this home grown application.
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I use a BS2 and a DS2760 w/ a type K T/C to control the temp. of the welder.
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I also use a precision air regulator set to 8" of H2O, This low air presser keeps the solder paste from spreading every were. (across traces)
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If you make one of these.Keep in mind that you need to bring the temp. of the welder up slowly.The low air flow and to much on time with the heating element will burn out the heating element quickly if your not careful. The PVC welder is use to seeing about 5 psi. This cools the heating element.
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I don't use any glue. I found it just gets into that last pin to solder and it wont take.Leaving a mess to deal with.
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I have made a really small C-Clamp to help hold the SMD for soldering.

LoopyByteloose

I've pretty much avoided SMDs as the 'solder paste' that was originally offered was quite expensive and had to be shipped quickly or packaged with dry ice - not exactly an import to Taiwan item.

But since the original shock, I have done a few hacks with SMDs. One can easily place a resistor or capacitor in tight quarters and ICs with merely 8 leads are easy to handle. The main tricks are to use plenty of flux and to pre-tin the circuit board before you place I items. I don't use a toaster oven, I just tack down items with a 30 watt iron. I am sure that the solder paste and a good regulated toaster oven are a cleaner build, but that isn't the only way to explore these.

Duane Degn

I was running out of room on one of my Propeller Proto boards so I used some smt resistors instead of the normal through hole kind. I took a bit of practice but now I rarely use a through hole resistor. They take up so much room. The smt (0603 size) resistors fit nicely between two holes on the proto board and I don't have to cut off the extra wire.

I have lost lots of these little resistors and capacitors. Some of them don't even drop, they just seem to disappear. I've begun to suspect I have a wormhole near my work table.

I use these boards a lot with the Prop. I use a SOIC EEPROM on the backside. I have to slice one of the smt pads in half to use the SOIC but then I have a nice small Prop board.

I use normal solder and soldering iron. I use solder wick to soak up the excess solder. It usually works great. I think the boards look nicer without the bulky resistors and capacitors.

Duane

Phil Pilgrim (PhiPi)

To keeping tiny parts form bouncing into a wormhole, you can use a small strip of self-adhesive magnetic material as a staging area, as I have attached to my Panavise:



-Phil

Searider

Phil,

Great idea with the magnet on the Panvice head and based on the background in the photo, I would guess there is no hope if you every drop one

StarMan

Phil, I like all the stuff in the background of that photo. You look busy.

What solder paste do you use? What model toaster oven do you recommend?

I've never tried reflow. I have only soldered smt with a soldering iron (Metcal rework station).

Chris

Phil Pilgrim (PhiPi)

Searider wrote:

...based on the background in the photo, I would guess there is no hope if you every drop one

You got that right! And, even if I did find it, I could never be sure that "it" was the one I dropped.

StarMan wrote:

What solder paste do you use? What model toaster oven do you recommend?

See my first post in this thread for a solder paste link. As to the toaster oven, I use a Panasonic NB-G100P that's apparently not made any more. It's not a convection oven, and I wish it were, since it limits me to very small boards. I would recommend an infrared convection oven with digital temp controls. Just keep an eye on Costco or Target, as their offerings often change.

-Phil

tonyp12

Solder paste, use very little
5cc http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=SMD291AX-ND
10cc http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=SMD291AX10
keep refrigerated (room temp when using), use it up within 6 months.
.
With a steady hand put a dib on every solder pad.
Choose SOIC chips if possible as they have 1.27mm spacing
Use 0805, 1206 or 1210 for resistors and caps.

$67 infrawave oven
http://www.orangeonions.com/product/FC150R/Black-Decker-Infrawave-Speed-Oven-Stainless.html
don't use if for food later, as lead fumes build up inside.

First the re-heat button, then the toaster button, done.
Adjust timings so the peek 220 celcius only last for 10 seconds
http://www.koki.org/Files/pdf/Tech/Reflow%20profile%20-%20general%20info.pdf

jrjr.

Things that haven't been mentioned here is how much
gravity and surface tension can be your friend or enemy
when hand soldering.

A lot of times a change in vertical positioning makes all
the difference when dragging a hoof across an SMD.

Also, pre-tacking the QFP's in the corner(s) is the only
proper way to achieve proper first pass alignments.

You can also pre-tack most smd's with flux enough to
get them to stay if the boards were properly whetted
when they were manufactured. ( this varies on board supplier )

You can also whet the SMD pad slightly to get a first tack.

jr

Don M

I just set up oven today. I bought a Black & Decker "InfraWave" model and modified it. http://www.amazon.com/gp/product/B00197VNYA/ref=pd_lpo_k2_dp_sr_2?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000I058PY&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0KYBY6R30AKFPGH7DKP2

To control the oven I bought a controller from The Silicon Horizon. http://thesiliconhorizon.com/store/silicon-horizon-techfx-reflow-making-your-reflow-oven-p-48.html?osCsid=2f7e524420d87be50927fd4f98ca3c78

I added an electrical box to the side that contains a SSR and the TechFX controller board.

I have been playing around with it today. Works quite well from what limited knowledge I have doing soldering this way.