TQFP to TQFP converter?

[markp]

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]

Hi All,

I have a major problem (at least it is for me!)

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

http://www.emulation.com/

Bob

 

[markp]

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

http://www.emulation.com/

Bob

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

Mark.

 

[Pooh Bear]

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.

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

 

[markp]

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.

PLCC packages are much bigger physically than TQFPs.

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.

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.

 

[Spehro Pefhany]

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.

I have to think that your best bet is to just learn what you can from
what you have and have the board(s) remade. Sometimes rework is not
worth it. Just change your procedures so it can't happen again, at
least not exactly the same way.


Best regards,
Spehro Pefhany

 

[markp]

I have to think that your best bet is to just learn what you can from
what you have and have the board(s) remade. Sometimes rework is not
worth it. Just change your procedures so it can't happen again, at
least not exactly the same way.


Best regards,
Spehro Pefhany

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.