I printed a board recently and, long story short, the pads aren't laid out correctly for two IC's: a SOIC8 MAX1771 and an 80-pin HV507. I moved all the pads from the top to the bottom layer, but forgot to flip the sides. Thus, along one side of the SOIC8 pads, for example, the connections number 4–1 instead of 1–4. I did something similar for the HV507. To give a better idea of the issue, if you pushed the IC through the board, then bent all of its pins upside-down, it would be connected correctly.

I can re-print the board, but I'd like to be able to test with the board that I have. That said, I've had difficulty finding a DIP adapter for the HV507. Is there any work-around for a reversed IC pinout that doesn't involve extensive new materials?

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    \$\begingroup\$ Google "dead bug soldering." Although for high-pin-count packages, that will be a pain. \$\endgroup\$ – Jon Watte Jul 8 '17 at 16:53
  • \$\begingroup\$ Jon Wattle OFF, but that nomenclature gave me a good laugh. \$\endgroup\$ – Neinstein Jul 8 '17 at 18:19
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    \$\begingroup\$ What EDA program are you using that allowed that? (Just wondering so I can avoid it.) The ones I've used know which side of the board the part is on and flip the footprint accordingly, so if the footprint is correct for the top layer, it can't be wrong on the bottom. \$\endgroup\$ – Jeanne Pindar Jul 9 '17 at 1:36
  • \$\begingroup\$ What @JeannePindar said - seriously, what is the software to avoid?? \$\endgroup\$ – FKEinternet Jul 9 '17 at 5:02
  • \$\begingroup\$ I did it in EAGLE, but it was my fault. I didn't use the mirror command; I just opened up the ICs' packages and changed every pad's layer from top to bottom copper. Guess I should've made the change from the board editor lol @FKEinternet \$\endgroup\$ – Jack Lynch Jul 9 '17 at 14:07

The 80QFP is thin enough that you may be able to place it upside down on the board, glue it in place, then carefully bend each pin down to its corresponding pad, and solder it. 80 pins is a lot to do that for though, this method is more commonly used on smaller chips.

I'm trying to find a good picture showing this technique.

At least, that's what I would do, just about any other method involving bodge wire (such as gluing it upside down and using wire to bring the pins down to the pads) or adapters will be very cumbersome with a package that size.

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    \$\begingroup\$ It is worth a try, but I think there is a good chance at least one pin will break. \$\endgroup\$ – mkeith Jul 8 '17 at 16:12
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    \$\begingroup\$ My experiance is that IC pins can be bent once to almost any position. Repeated bending is likely to break them. \$\endgroup\$ – Peter Green Jul 8 '17 at 17:12
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    \$\begingroup\$ All 88 pins on the two IC's have been successfully bent. Thanks! \$\endgroup\$ – Jack Lynch Jul 8 '17 at 18:32
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    \$\begingroup\$ That is great! I am glad I was wrong. I have had bad luck with bending SOT-23 pins, even once, but I guess those pins are a bit longer and so the bend is not as harmful. \$\endgroup\$ – mkeith Jul 8 '17 at 20:12

While the procedure given by uint128_t is probably best, here's another.

Get yourself a spool of bare 30 gauge wire. Solder a short length to each pad, with each piece perpendicular to the row of pads. Now place the IC on its back, but use something like superglue or RTV to tack it in place. Now bend each wire 180 degrees and solder to the appropriate lead, and snip off the excess. Now use something like 5-minute epoxy to run a bead around the pad area, fixing the jumpers in place without shorting to each other.

uint128_t's idea is, as I say, probably best. With the chip in place (and tacking it down is a good idea), use a fine-tipped probe to bend each lead into position. Do this with a single, strong push and you are unlikely to fatigue the leads.

Either way, it's going to be a tedious process.

  • \$\begingroup\$ “use a fine-tipped probe to bend each lead into position.” I would use something flat, like a ruler or sheet of metal to uniformly bend all the pins on each side. Much less likely to overdo it this way. \$\endgroup\$ – Michael Jul 8 '17 at 18:05
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    \$\begingroup\$ You'll probably find that 30 gauge wire is effectively too big to make a sequence of adjacent contact to a QFP, being more than half of the pin pitch distance and leaving less than 6 mill of gap to avoid shorting the wire on the next pin. You'll need something like fine strands pulled from a flexible mains power cord, and even with a nice soldering microscope it's unlikely the project will be completed. \$\endgroup\$ – Chris Stratton Jul 8 '17 at 18:33

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