hi again,
i would guess then that this cracking would be apparent when you receive the parts. do you have any left over that you can examine? maybe the cqfp vendor has some of these parts from the same lot code that haven't been formed yet that they (or you) could examine. if your customer supplied you these parts, maybe they have some more that could be tested.
if you machine place these parts, i'm sure that your customer and the part vendor are going to ask you if you might have damaged them during lead forming or part placement.
so much work; so little time.
phil
-----Original Message-----
From: Stephen R. Gregory [mailto:[log in to unmask]]
Sent: Monday, January 29, 2001 3:47 PM
To: [log in to unmask]
Subject: Re: [TN] CQFP cracking...
Hi Phil,
Still trying to get all the details of what kind of ESS they put the
assemblies through.
The reason I asked if it was possible that we may have gotten a suspect batch
of parts, was that we were told by the vendor who does the form, trim, and
pre-tinning of these parts for us, said he has run across this in the past,
and it has been traced back to a problem when the silicon was packaged into
the IC...I'm not familiar enough with the process to know any different.
BTW, the vendor that does this service for us is VERY experienced doing this,
they do this for a living, and have a long list of customers (Semiconductor
OEM's included) that they've been doing business with for quite a while...
I'll have to get more details about everything (ESS parameters, etc.) so I
can ask more intelligent questions...
-Steve Gregory-
<< hi,
under what conditions are they cracking (eg vibration, temperature cycling)?
is there anything the customer is doing now that they werent' doing before.
phil
-----Original Message-----
From: Stephen R. Gregory [mailto:[log in to unmask]]
Sent: Monday, January 29, 2001 3:08 PM
To: [log in to unmask]
Subject: [TN] CQFP cracking...
Hi all,
We build a board here that's been built here before, using the same
processes. It is around 8" X 8" polyimide fab, that has two very large
352-pin CQFP's on it. One of the customer requirements is that these parts be
bonded to the board using Loctite 3615.
So we print paste, then dispense the epoxy, place the parts, and then
cure/reflow the assembly.
With this last build we've done, the customer is reporting that the CQFP's
are cracking during their thermal cycle and vibration tests. This has not
happened before.
Is it possible that we have gotten a suspect batch of parts? Has anybody else
ever run across this type of problem before?
Thanks!
-Steve Gregory- >>
---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------
|
