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Re: SOIC Packages For S100 Boards - Survey Question

On Wednesday, December 31, 2014 3:12:25 PM UTC-6, Don Caprio wrote:
I'm curious how you guys feel about using SOIC chips
instead of the traditional DIP.

Honestly I find them easier to solder not harder. lay flat wipe wipe done.  A little kapton tape goes a long way.  The bigger the chip the easier they are to solder.  Just like thruhole the first ten smd components are kinda rough and the first 100 are not perfect but after awhile its no problem.  Nobody does thru-hole on 3 ghz ham radio transverters or microwave synths so I have some practice...  Its a lot easier to practice on "giant" SOIC than on 0102 caps.  I hand solder because when I was young and poor in the 80s/90s that how I had to do microwave stuff so I got good at it.  I know reflow is faster and someday I'll get one of those ebay ovens.  But I soldered a lot of MMICs in the 90s by hand...

I'd worry about no sockets, rework mods, and test points. 

No sockets is kind of icky.  I yanked all the chips out of my ECB PropIO v1 and stuck them in a v2.  Guess I'd have to buy all new for SOIC.  Sometimes after pulling my hair out for days I'll start swapping chips, swapping logic families, and that's not happening with SOIC.  I found a dead (used) 7432 on a ECB z80 card that way.  Of course I could just not use ttl pulls.  Then again I don't know if there is such a market as SOIC pulls...

Rework along lines of "pull this pin out and solder jumper to that trace" are non-trivial.  You'll have to do it all on traces not leads.  Make sure theres flat straight FAT trace out of the pin for awhile in case of needing this kind of mod.  Of course that might use space.  Another solution is ver 1 is thru-hole and later versions all get SMD and maybe extra features added.  Another thought is extra features get SOIC treatment but core board function gets thru-hole.  So the soic package RTC doesn't work on my board, the rest of the board is just fine, or the memory backup bypass is bad, well, some cut traces and fat wire jumper will fix that rather permanently.  Some boards are utterly packed, but some have some space and its interesting to think about what could be optionally wedged into place using SOIC (and smaller) sized SMD.  I like QFPs.

Hard not to bridge two SOIC traces when using a probe to test.  Could put a via that does nothing but make a convenient test point, can find some thru hole.  Could put in formal silk screened test points, that might be kind of cool... 

Just ordered some parts yesterday, getting harder to find thru-hole, maybe you'll get one choice, but you'll have 10 choices in SOIC.  Best get used to it now.