>From the EMPF HelpLine in Indianapolis: Here a few things to suggest on this request: > >First, I would suspect the pot temp is marginally too low for this assy >type. Try moving the temp closer to 490F for this assy and monitor the >results. Grainy joints from low pot temps are common. > >Next I would verify that the topside temp that they are reaching is within >the process window spec from the flux manufacturer for the type of flux >being used. Might be too cool. Adjust accordingly. Conveyor speed could >possibly be adjusted slightly to achieve the desired topside temp for the flux. > >Next I would verify that there is no board contamination associated with >this assy different from the ones that run successfully. Age, handling, >plating, etc. > >Lastly, I would verify that the boards are not being removed from the wave >system while the solder is still molten. On some TH assemblies with larger >thermal mass, sometimes the joints have not sufficiently cooled before they >are removed giving the "disturbed" grainy look to the joints. > >Hope this helps. > >Pat Kane >Manufacturing Research Engineer >EMPF > >At 09:53 AM 5/14/96 -0500, you wrote: >>>X-POP3-Rcpt: crawfoj@ginger >>>Resent-Date: Tue, 14 May 1996 09:00:34 -0700 >>>Resent-Sender: [log in to unmask] >>>Old-Return-Path: <[log in to unmask]> >>>Date: Tue, 14 May 1996 21:10:59 +0800 (SST) >>>X-Sender: [log in to unmask] (Unverified) >>>Mime-Version: 1.0 >>>To: [log in to unmask] >>>From: Poh Kong Hui <[log in to unmask]> >>>Subject: RE:ASSY: >>>Resent-From: [log in to unmask] >>>X-Mailing-List: <[log in to unmask]> archive/latest/4118 >>>X-Loop: [log in to unmask] >>>Precedence: list >>>Resent-Sender: [log in to unmask] >>> >>>Dear Technet, >>> >>>Whenever, I'm running a 100% through-hole board, that is densely populated >>>with mainly DIP components, and a only few capacitors and resistors., 20 to >>>30% of the solder joints are gritty. >>> >>>It had never happened to board of mixed technology. >>>I have sent the solder for lab. analysis, and the result is within the >>>recommended specification. >>> >>>The Board is :- >>>10 x 10 sq.inch >>>4 layers >>> >>>The wave-solder Machine used :- >>>The wave-solder machine used is SEHO 2000 - a full-blown nitrogenous tunnel. >>>The solder pot temperature is set at 245 deg.cel or 473 deg.F. >>>The top side temperature is measured at about 194 deg.F / 90 deg.C. >>>Conveyor speed is set 0.90 metre/minute. >>>The solid content of the flux is 1%. >>> >>>Could anybody advise me why this is happening, and how to solve it. Our >>>rework operators are touching every gritty joint. >>> >>> >>>Poh Kong Hui >>>Nera Electronics >>> >> >> Jack Crawford >> HelpLine Manager >> EMPF >> 317.226.5616 >> Visit our homepage at: >> http://www.empf.org >> >> >> Jack Crawford HelpLine Manager EMPF 317.226.5616 Visit our homepage at: http://www.empf.org