SSOP to SSOP adaptor PCB - Page 1
Forum section: electronics / general

author: Dankoozy
author_rank: Contributor
timestamp: October 04, 2022, 10:43:33 pm
content: I have some PCBs to repair with an out of stock PIC on them in ssop package. Would I be a sinner to make a small PCB the size of a SSOP package that I solder onto the PCB and put another SSOP PIC that is in stock on top of that?Anyone tried it before?

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 05, 2022, 04:00:57 am
content: Not sure what the adapter would be if both footprints are identical? Or are those SSOPs with a different pin count? (I guess so?)Not sure why it would be a sin.Just wondering how you're going to design this PCB to be solderable as a SSOP package directly though? Castellated holes? To do this, the new microcontroller should be much smaller than the original?

author: Berni
author_rank: Super Contributor
timestamp: October 05, 2022, 05:26:35 am
content: It is possible but it has to be soldered BGA style.In most cases it makes more sense to find one in a smaller package such as QFN and then adapt that.

author: jpanhalt
author_rank: Super Contributor
timestamp: October 05, 2022, 05:37:34 am
content: Please give specifics for the PIC being replaced and the one you plan to use.

author: TomS_
author_rank: Frequent Contributor
timestamp: October 05, 2022, 06:43:28 am
content: You might find that getting such a small PCB made may be impossible or very expensive.On the other hand, maybe a flexible PCB with a section that you cut off may be doable.

author: hans
author_rank: Super Contributor
timestamp: October 05, 2022, 09:17:20 am
content: SSOPs are mostly 0.5-0.8mm pin pitch, so that sounds very hard/impossible to do with castellated holes.Maybe soldering 2 sides of a flex PCB/flat cables to the existing footprint and adapter PCB can work.

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 06, 2022, 06:13:11 pm
content: Quote from: hans on October 05, 2022, 09:17:20 am0.8mm is not much of a problem. 0.5mm starts becoming one. I've made PCBs with 0.5mm pitch castellated holes (not my choice!) and PCB manufacturers that could do this were not many and that was expensive. But yeah, forget about even 0.8mm if your goal is to go with cheap manufacturing such as JLCPCB.As to designing the adapter with small matching pads on the bottom layer, good luck with assembly.We don't know what PICs the OP had to deal with. Microchip has such a wide offering that it would be unlucky not to find an alternative that was pin-compatible. But yeah, at the moment practically nothing is available except for stuff you don't need. So...

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 09, 2022, 01:07:14 am
content: With SO/SOIC (1.27mm pitch) you should easily find inexpensive smd headers like this matching the footprint:But for SSOP/TSSOP (0.65mm pitch) you'll have a hard time... Perhabs buying rare/expensive board-to-board connectors like Hirose DF15 series.

author: NorthGuy
author_rank: Super Contributor
timestamp: October 09, 2022, 02:11:07 am
content: I did this once for prototyping when I screwed up the pinout on a 6-layer board.It was 0.4mm pitch, so it took very little solder and didn't work from the first try, but I made it work. With 0.65mm pitch, you can put much more solder on it, so it'll be easy to fix.