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November 1998

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Subject:
From:
Jeff Hempton <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 6 Nov 1998 09:39:10 -0500
Content-Type:
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     We are evaluating heated, ultrasonic stencil cleaners and liquids.
     We are evaluating detergent based liquids, and heating them to 120
     deg. F greatly enhances their cleaning capabilities.
     We are using no-clean solder paste, type mesh 3, at .020" pitch
     components.
     I am aware that you must stay below certain temperatures and times at
     temp to keep the epoxy from de-bonding from the stencil to the wire
     mesh, but, from articles I've read ("...recommend keeping liquid temps
     below 110 deg. F"), this seems somewhat ridiculous to me, so I want to
     ask:

     Is there a concern that temps could
      "expand/warp/change pitch/permanently deform" stainless steel (we use
     .006") in the fine-pitch or ultra-fine pitch areas?

     Any experience you "fine pitch swamis" have would be greatly
     appreciated! Thanx in advance!

     United Technology Electronic Controls
     Jeff L. Hempton, Sr. SMD Engineer
     E-mail: [log in to unmask]

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