Teo: How are you? If your concern is about solder paste residues causing
false-fails with ICT, then your concern should be with both the nature
(softness/hardness) of the residues, as well as the amount of residue. One
way of reducing the amount of residue left is by using low oxygen levels in
the reflow process (Thibault, Bell and LeMieux, "Reduction of Residue Using
Various Nitrogen Atmospheres", Proc. NEPCON West , 1998). However, even a
small amount of a hard flux-residue can cause false-fails, and brittle
residue can build up on test-probes over time.

A test called the 'force to contact' test was developed a while ago, and
David Guo of Alpha Metals is doing a paper at NEPCON this year on
improvements to this technique, which may prove interesting to you (I
haven't seen it!). Also, Doug McKernan of AmTech has drafted a section for
the IPC Solder Paste Task Group's upcoming "Guidelines for Solder Paste
Assessment" on pin-testing of solder paste residues.

'Pin-testable' solder pastes have been developed by most
paste-manufacturers, and I suggest that you contact them and ask for their
recommendations.

Andy Mackie





[log in to unmask] on 02/08/99 08:52:01 PM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to [log in to unmask]

To:   [log in to unmask]
cc:    (bcc: Andy Mackie)
Subject:  [TN] solder paste residues




I am trying to quantify the residues left over after reflow from no clean
solder
paste.  We have an omega meter in the facility that gives you an ionic
measurement (resistivity and NaCl/inch).  Is this an adquate measurement?

I am qualifying new pastes, and there is a concern in the ICT area about
residues.  Are there any other alternative methods of quantifying solder
paste
flux residues?

-Teo Tijerina

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following
text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section
for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or
847-509-9700 ext.312
################################################################

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################