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1996

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Subject:
From:
[log in to unmask] (Jack Crawford)
Date:
Tue, 14 May 1996 13:42:33 -0500
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>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
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>>>
>>>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




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