Hi Jorge, I'm not sure I understand the difference between solder beads and solder balls, are the beads smaller? Water soluble paste will pick up moisture and lose structure in high (>50% RH) humidity conditions. You could be getting excessive flux flow out during reflow preheat and with it small individual particles of solder powder washing out and creating micro-balling. Or You could have a volcanic effect whereby the paste explodes during the reflow process spattering solder balls all over, this is also likely if there has been an increase in moisture content in the paste. Or The powder in the paste is not particularly good and is not fusing properly and creating a lot of micro-balls. Could be anything really. What paste are you using? Best regards, Andrew Hoggan BBA Associates Ltd www.bba-associates.com -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Jorge Rodriguez Sent: 21 August 2001 19:57 To: [log in to unmask] Subject: [TN] Solder Beads (not solder balls) Fellow technetters, We are having tons of issues with solder beading, even on boards were we didn't have the issue before. We're clueless, we suspect of the solder paste (63-37 Water Soluble), it looks slumpy amd watery, but we're not sure. I know solder beading can be solved by designing the stencils with home-base aperture, but what we're seeing here is across the board, not just one particular assembly but several. Does anyone have experience dealing with an issue like this?, could solder beading caused by the oven profile or is it more like solder paste related? Any comments would be appreciated. Jorge Rodriguez Process Engineer Varian Electronics Manufacturing E-mail: [log in to unmask] ---------------------------------------------------------------------------- ----- 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 To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL 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 ---------------------------------------------------------------------------- ----- --------------------------------------------------------------------------------- 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 To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------