Mike,

You will find that in IPC A 600 E  (Acceptability Guidelines)  and in IPC RB 276 section 3.11 the mask requirements are clearly defined. With regard to mask coverage of reflowed parts, the requirements would be the same since the concern is not with potential exposed copper degradation but potential bridging of conductive surfaced during assembly.

Hope this helps,

Ed Cosper
Director Quality Assurance and Engineering
Graphic Electronics Inc.
Tulsa, OK 
   

----------
From:  Mike Masters[SMTP:[log in to unmask]]
Sent:  Tuesday, March 25, 1997 6:56 AM
To:  [log in to unmask]
Subject:  Solder Mask Coverage and exposed SN/PB and Copper


I have a question that is two fold.  It concerns Solder Mask coverage on PCBs.  
IPC 610B addresses this issue some what but does leave a lot out.  I am tasked 
to set a standard for Mitsubishi Semiconductor for solder mask coverage on PCBs 
and to determine when the manufacturer fails the criteria.

	1.  Question 1:  What publications are available showing industry 
	standards for solder mask coverage over bare copper as well as over
	SN/PB?  I am aware of IPC 610B.

	2.  Question 2:  Hoe much solder mask coverage is necessary for traces
	that are already SN/PB coated?  I do have a standard for exposed bare
	copper.  I am thinking especially for those traces that are adjacent to
	each other with at best an 8 mil lines and spaces.

Any response would be helpful,  Thanks


-- 
    /\    
   _\/_   
  /_/\_\  

Mike Masters
QA Materials Engineering Section
Office: (919) 479-3771
FAX:    (919) 479-3328
Internet:  [log in to unmask]



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