SparkFun Forums

[victorf]

I have had some success at do-it-myself SMT board reflow soldering. For components like capacitors, resistors, LEDs etc, I have confined myself to the larger 1206 size. I have recently had some luck with using SOIC packages. I have a syringe of paste solder and some fairly small bore tips and can usually get the solder on the pads in a manner that gives acceptable results. I had to struggle to do the SOICs tho. I would also like to use a 44-pin TQFP in a future design.

I need to find a better way to place ths paste on the SOIC and TQFP pads and to place the component on the pads. I had a thought that it might be possible to glue the SOIC and TQFP component on the board with a drop of some sort of adhesive. Aligning the device pads to the board pad is difficult and if someone has a suggestion, I would appreciate hearing it. In fact, I would like to hear any suggestions for using SMT components in home-brew projects. I have considered using a magnifing TV system to help me to better see what I am doing, but these are quite expensive. Anyone home-brew one of these? I would like to find one of those vacuum pickup devices (what is the official name?) to help position components. I am currently using twezzers(sp). Anyone home-brew one of these? I am aware of Toaster Oven reflow devices. In fact, I use the Spark Fun idea of a Electric Fry Pan for my reflowing. I am happy with the results.

Any enlightenment will be appreciated.

Vic

[Kuroi Kenjin]

Actually professionally, they do use a little adhesive. Have you tried using solder stencils? Also, I've read a bit that you can be a bit sloppy with solder paste, the solder mask and the solder's adhesion should line them up and bubble apart. I haven't tried this yet, as I am still working on getting in a PCB for a reflow oven controller.

[Philba]

chip caps and resistors - hand solder. I pre-tin one pad, flux the leads and use forceps to hold the part while touching the iron to the tinned pad. fast and easy. use magnification if it's hard for you to see. I can do 1206s and 805s easily but smaller is still possible.

SOTs - pretty small but doable by hand.

SOICs - same thing. tin a corner pad and use that to hold the soic in place. solder the rest of the leads and touch up the corner pad. for soics, reflow is overkill. solder wick is your friend. get the really small stuff.

tqfp and other tight pitch devices are hand solderable but alignment is a little tricky - the key is to have a solder mask on the pcb. with reflow and the right amount of paste, the surface tension of the molten solder will cause the chip to self align. It might need a little vibration (like a tap) to seat correctly.