Rich: I have seen similar problems on double sided SMT when run thru in-line
aqueous wash. For a sanity check you may want to put a trap or screen in
your wash and rinse drains to see if you are loosing components in the wash
process. If that's the cause then  I would recommend placing the boards in
fixtures that support them off the belt. We have been doing this for quite
awhile with good results.
Another place to check are storage racks, carts and totes. We found that
they were also causing similar problems of breaking or tearing off
components especially those close to the edge of the board.


Regards

Michael Barmuta

Staff Engineer

Fluke Corp.

Everett WA

425-446-6076




-----Original Message-----
From: Rich Lasko [mailto:[log in to unmask]]
Sent: Monday, February 24, 2003 9:43 AM
To: [log in to unmask]
Subject: [TN] Handling Damage of SMT Components



Good morning everyone,



I am encountering a random problem with damage (components being cracked and
sometimes broken off) to some SMT components on the secondary side of the
board.  (Most of the damage is to the SOT-23's and chip resistors/capacitors
(0805).



Here is the summary:



I have a double-sided SMT board with Thru-hole components on the primary
(top) side.  Board thickness is approx. 0.093".  The board is approx. 16"
long and 12" wide.  I believe I have isolated the root cause to be the
in-line wash system that this board is sent through.  (Electrovert Aquapak
544 - And yes I know it's old - Ha!)  The operator lays the board on the
stainless steel "mesh" primary side up.  This can not be good for the SMT
components on the bottom side.  (Argggg)  Has anyone else encountered
something similar to this.  If so, what changes were made to help protect
the board during the cleaning process?  I am concerned that any "bouncing
around" that happens during the wash cycle is cracking/damaging these SMT
parts.  Thoughts...



Any help would be appreciated.



Rich Lasko

Badger Electronics

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