TECHNET Archives

June 2011

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
"Thayer, Wayne - IIW" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Thayer, Wayne - IIW
Date:
Thu, 23 Jun 2011 19:21:51 -0400
Content-Type:
text/plain
Parts/Attachments:
text/plain (1 lines)
Hi Sri-

Most likely cause is poor adhesion between the molding compound and the top surfaces of these passives.  During post mold reflow, the molding compound swells, causing the solder to be put under a mild amount of pressure.  A very tiny crack opens up along the surface and you get your "wicking".  I call it "solder squirt", and it happens often when I rework dense BGAs which are underfilled.

You need to investigate/attempt to quantify this adhesion and fix the problem with cleaning procedures, surface treatment processes, different molding compounds, or pre-coating the passives with something which sticks better.

Wayne Thayer

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Sri Maganti
Sent: Thursday, June 23, 2011 6:19 PM
To: [log in to unmask]
Subject: [TN] Solder wicking on component topside at 1st level

We are having a strange issue for some time that we are not able to completly lay our hands on in terms of identifying the root cause. We tend to see solder wicking [ shorting of the terminations ] on top of capacitors/resistors after post mold reflow [ not 1st reflow after assembly]. Our efforts indicate that MSL 1 tends to aggreviate it or rather we are able to duplicate the failure mode using MSL1. The devices /process that are in question are MSL3. I am looking to see if we have a guru or rather an expert in this field who we can consult with. Any leads or names of subject matter expert in this diretion will help and truly be appreciated. Obvioulsy we miss warner englemaier to brainstorm on cases like this.

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

This e-mail and any files transmitted with it may be proprietary and are intended solely for the use of the individual or entity to whom they are addressed. If you have received this e-mail in error please notify the sender.
Please note that any views or opinions presented in this e-mail are solely those of the author and do not necessarily represent those of ITT Corporation. The recipient should check this e-mail and any attachments for the presence of viruses. ITT accepts no liability for any damage caused by any virus transmitted by this e-mail.

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________




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

Technet Mail List provided as a service by IPC using LISTSERV 16.0

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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)

To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest

Search the archives of previous posts at: http://listserv.ipc.org/archives

For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815

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


ATOM RSS1 RSS2