TECHNET Archives

May 1997

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:
Date:
Thu, 1 May 1997 17:14:07 -0400
Content-Type:
text/plain
Parts/Attachments:
text/plain (54 lines)
     I have a multilayer RF PWB application, using Rogers' Duroid 6002, 
     procured to IPC-HF-318.  FEP film is being used as the bond film, 1/2 
     ounce copper is used on the innerlayers.  The part is used in a 
     high-reliability application.
     
     The problem is that a large percentage of product is being failed at 
     microsection due to excessive smear.  IPC-HF-318 allows up to 25% 
     smear along the vertical interconnect at the T-Joint.  We regularly 
     see T-Joints with up to 50% and 75% smear.  Not all holes in all 
     sections have this much smear, but if it happens in one hole, the 
     entire panel is rejected.
     
     RF tests show that, regardless of the amount of smear seen in the 
     cross-section, the boards are electrically (RF) acceptable.  Also, 
     we've performed thermal cycle testing which indicated no degradation 
     in RF performance.
     
     SEM micrographs of "as drilled" holes confirm that the smear is due to 
     the drill operation.  Two sets of drill studies have been performed, 
     with only marginal improvement.  The smear is not removed when 
     subjected to plasma cleaning.  
     
     My questions include:
     - Is this amount of smear unusual?  If it's not, should IPC-HF-318 (or 
     its successor) be changed?
     - Have others seen it before?
     - Is this another quirk of 6002?
     - Was IPC-HF-318 written for 1 ounce copper, therefore implying that 
     .00035 inches of smear (25% of 1 ounce copper) is really acceptable?
     - Is there any embraced reliability data that may indicate it is not a 
     reliability problem?
     
     I would appreciate any help in either reducing the problem (smear) or 
     in determining that IPC-HF-318 is not the appropriate criteria to be 
     used in accepting/rejecting this condition.
     
     
     Andy Pedersen
     Harris Corp.
     [log in to unmask]
     407-729-2143

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]>   *
* with <subject: subscribe/unsubscribe> and no text in the body.          *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact   *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      *
***************************************************************************



ATOM RSS1 RSS2