Jonathan,

Could it be that your reflow process does not allow sufficient time to bring
the entire 'system' (top and bottom metal pieces) up to liquidus?

Steve Creswick
Gentex Corp

-----Original Message-----
From: Jonathan A Noquil [mailto:[log in to unmask]]
Sent: Friday, May 11, 2001 5:56 AM
To: [log in to unmask]
Subject: [TN] Solder Voiding


Hello Everyone,

Please help,
Can Anybody explain why too much voiding
occurs when two metal is joined (Top Metal
and Bottom metal)? Eventhough the peak temp is
40 C over than the liquidus temp of the solder.
When a solder is reflowed without top metal
the solder wetting is very good and the appearance
is shiny. But when you put a top metal to be joine
and then X-ray, there are a lot of voids.
I tried to removed the top metal, and the picture
below showed a lot of voids. Another thing is the
color is not shiny but grayish.




(Embedded image moved to file: pic29915.pcx)

The paste is 85Pb/10Sb/5Sn
Peak temp is 290 C
Oven: Conduction
Time until the unit is out: 180 Seconds.


Many thanks to everybody.

Sincerely
Jonathan

----------------------------------------------------------------------------
-----
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
---------------------------------------------------------------------------------