TQFP to TQFP converter?

Question

Hi All,I have a major problem (at least it is for me!), I used a 44 pin plcc schematic symbol, but the PCB itself has a 44 pin tqfp footprint :-(. The positions of the signals on the chips are the same, but of course qfp packages have pin 1 in a corner while plccs have pin one half way along one edge. So, I need a method of converting the pinout.Any suggestions? I was thinking of a small PCB about the same size as the TQFP footprint with a TQFP footprint on both sides, using a solder mask and paste to connect that to the main PCB. I would effectively be creating an LCC with a pin-swizzled TQFP on the top. I have two prototypes already built and another 8 PCBs that I don't want to chuck away.The things that worry me are:1) would the solder connections be reliable?2) What chance of shorts/opens?3) Power would have an extra few mm to trace out without very close decoupling.Any views?Mark.

Bob · Accepted Answer

Try these people. They've saved my ass several times.Bob

markp · Answer

Thanks Bob, I'll ask them if they have anything suitable.Mark.

Pooh Bear · Answer

Why don't you just use the right package for the device as the pcb is laid out for ? I can't see what you're trying to achieve.

You need to keep an eye on those layout guys btw. That's a classic error. Nearly had my own guy try that one on me.

Graham

Spehro Pefhany · Answer

I have to think that your best bet is to just learn what you can fromwhat you have and have the board(s) remade. Sometimes rework is notworth it. Just change your procedures so it can't happen again, atleast not exactly the same way.  Best regards, Spehro Pefhany-- "it's the network..."                          "The Journey is the reward"             Info for manufacturers:  software/hardware/analog  Info for designers:

markp · Answer

PLCC packages are much bigger physically than TQFPs.Well this case it was my fault, I used a PLCC schematic symbol with a TQFP footprint on the PCB, can't blame anyone else :-(.Mark.

markp · Answer

Yeah, I've removed the PLD and I'm checking out what I can of the rest of the circuit - reworking is fine but it'll take a long time doing it manually. I reckon it just might be possible to do the swizzler, but I'm waiting to see if there are any more cockups before I do anything else. What a bummer, I was hoping to get this sorted over this holiday period. Oh well!

Mark.

TQFP to TQFP converter?

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