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May 2000

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Subject:
From:
"Taheri, Kamran" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 10 May 2000 15:06:12 -0500
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Since we are on this subject! Dose tombstoning occur during the
liquefying(reflowing)stages of the solder paste or when is
solidifying(cooling down)?

-----Original Message-----
From: Bev Christian [mailto:[log in to unmask]]
Sent: Wednesday, May 10, 2000 2:40 PM
To: [log in to unmask]
Subject: Re: [TN] Tombstoning and missing parts on 0805 Resistors


Alejandro,
You have two problems here and they may or may not be related.  Tom has
given some good things to look into.  Also, for the tombstone situation
check the size of end caps on the chip resistors.  I have seen the situation
where there was a big end cap at one end and a small one at the other end,
resulting in differential wetting forces pulling the caps into a tombstone
position.

regards,
Bev Christian
XLTEK

-----Original Message-----
From: Becerra Alejandro [mailto:[log in to unmask]]
Sent: Wednesday, May 10, 2000 10:27 AM
To: [log in to unmask]
Subject: [TN] Tombstoning and missing parts on 0805 Resistors


Hi Technetters,

 We are having some problems with tombstoning and missing parts on 0805
resistors.
 We think that the problem is related to the component, since we only detect
the problem in some specific codes of the material.
 Could you please tell me what can I look in the components?
r end cap one on end than on the other end.

regards,
Bev Christian
XLTEK
Thanks in advance

Alejandro Becerra
MSC
Phone (915)841-8518,  Fax (915)841-8401
[log in to unmask]

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