Wells-CTI BGA Socket Alignment Issue?

Recently, someone in the SMTNET forum had installed a Wells-CTI Z-Lok socket and found that it was one row off from the board layout pads. Was the problem due to a layout error or was the datasheet incorrect?

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| Recently, someone in the SMTNET forum had installed a Wells-CTI Z-Lok socket and found that it was one row off from the board layout pads. Was the problem due to a layout error or was the datasheet incorrect?

Dave ol' pal...dat wuz me...

A freind of a freind (yeah, it was one of those deals) brought the board over for me to try and rework. It was a BEAR! I was able to get it off, but soldering it back on, especially without the guide pins, forget it! The alignment issue was one thing, but because that socket has so much plastic around it, and the board that I was working with was so big, I couldn't get it back on. The board would either warp so bad that the outer pins around the periphery wouldn't be touching the board, or if I tried to lower temperature down to where the board wouldn't warp, I would have cold solder.

To me, with that socket, you only got ONE chance to get it down. If you blow it the first time, that's it...

I spoke with a guy named Peter Baker in CTI's Arizona office about this, and he said when I asked about how you went about reworking this beast, that the only company he know's of that has the rework down is SCI, and even then, Peter said they modified a rework machine somehow JUST for this socket.

I never have really gotten down to the bottom of why it was laid-out wrong...everybody is pointing their fingers at each other. CTI said that the people who laid-out the board never called and asked for an "official" footprint, they used the dimensions thats up on CTI's WEB page, which Peter says is a generic drawing. Peter also said that there are two versions of the same socket. They changed the foot of the leads to make it half the length of what it was and shifted one dimension slightly, so that the foot of each pin would be centered up on the pads. The way it was before, because the foot was so long, that it would hang off the pads. Peter did tell me that if somehow they laid out the part according to the old socket dimensions, and wound-up with a new socket, that the changes wouldn't have caused it to be soldered a whole row off. So I don't know for sure what happened that caused the alignment holes to be so far off...personally, I think the lay-out guy screwed-up big time!

This has been the second or third BGA socket I've dealt with, and I tell you what...I personally think that if one wants to socket a BGA, they should use a PTH to BGA socket. Hell of a lot less trouble that way. Problem with the surface mount ones is that you can't rework em' (I haven't figured out how to do it yet anyway...I can take em' off, but not put em back on)

-Steve Gregory-

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Hey Dave!!

I almost forgot, I got both footprint drawings, the new and the old...if ya' want, send me a email with your FAX number and I can FAX them to ya'...

-Steve Gregory-

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