TECHNET Archives

November 2000

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:
Earl Moon <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 15 Nov 2000 11:28:32 -0600
Content-Type:
text/plain
Parts/Attachments:
text/plain (30 lines)
I guess pictures would be in order. Verbally, it seems your paste is wetting
as required to the pads but what's with the "mounds?" The solder balls are
deforming but "smershing" down into the COMPLETELY melted solder paste as if
displacing it. So, what's wrong with the missing picture? Why are the solder
balls incapable of wetting? Contamination? Oxidation? Wrong alloy?

I see your HASL finish as acceptable and wetting normally. What's with the
tinned and fused finish. Is it really tin/lead plated and fused?

Anyway, besides the possibility of the solder balls being incapable of
solder wetting, what is the recommended solder paste profile and how close
are you to it - really? And, again, the corner balls will be hotter causing
them, most often, to collapse first though this is dependent upon the rest
collapsing or a non-parallel device to substrate condition will exist and
will be easily seen - leaving the rest to follow, including the ones
internal to the device and array pattern. In other words, the corner balls
will "melt" first but will not collapse until all others do the same
depending on number.

Earl Moon

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

ATOM RSS1 RSS2