At 06:13 PM 6/7/2002 -0700, Dennis Saputelli wrote:
>i've got a 144 pin PQFP 0.5mm pitch
>there are only a small number of connected pins, maybe a dozen or so
>excluding power
>i am thinking about deleting a lot of unused pads to possibly open up
>top side routes and reduce inspection and bridging concerns
>am i crazy?

Dennis, yes, you are crazy :-), but that doesn't answer the question.... 
Even crazy people sometimes have good ideas....

>do you think the leads will short thru the solder mask to traces below?

Mr. Selfridge gave a good answer, I think. But maybe the idea does not have 
to be completely tossed.

>is this good practice even if i don't run traces there, i.e. will it
>solder and align properly with missing pads?

As an experiment, you might try this:

Determine a set of pads that you want to solder, make it symnetrical so 
that the part will be firmly held. Maybe most pads would be soldered, or at 
least more than half. Do leave solder mask openings so that the extra leads 
are not stressed, but the openings might be reduced a bit. This *might* 
allow you to run a thin trace between the pads, but I wouldn't be on it. If 
it will not be enough to allow 1-thrus, I'd leave the mask openings the 
same as for the pads to be soldered.

The only advantage of this, in the latter case, would be less possibility 
of bridging, but I don't know how much of a factor that is, anyway, my 
knowledge of current assembly criteria is somewhat in need of renewal....

In short, however, the whole affair is probably not worth the trouble, but 
ultimately that is an engineering question which I am sure you are 
qualified to answer.... with a little help from your friends.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* To post a message: mailto:[EMAIL PROTECTED]
* To leave this list visit:
* Contact the list manager:
* Forum Guidelines Rules:
* Browse or Search previous postings:
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Reply via email to