Just would like to correct my item # 7 on the processes each unit will
undergo.Curing is "2 hours" minimumn not 8 hours - sorry..

Any inputs - please read my message below.

>From: Enrique Lodangco <[log in to unmask]>
>Reply-To: "TechNet E-Mail Forum." <[log in to unmask]>,        Enrique
>Lodangco <[log in to unmask]>
>To: [log in to unmask]
>Subject: [TN] Epoxy (clear or black) wicking on leads? How to control and
>            and              possible root causes.
>Date: Sun, 5 Sep 1999 01:49:53 +0800
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>Hi to all of you!
>
>I'm one of the new members of this forum and for a start I just would like
>to know more about controlling epoxy wicking (capillary effect) on IC
>leads.
>
>We are currently assembling module devices (Non Volatile SRAM's) for one of
>our customers. Our biggest problem now is on how to control this phenomenon
>during encapsulation process. This customer of ours have been doing this
>for almost 10 years but problem was not eliminated. They just recently
>transferred these operations (consigned everything) to us together with the
>said problem.
>
>To give you a background:
>
>1. We manufacture these SRAM's or modules using leadframes (tin plated,
>alloy 42 base metal) as the leads.
>2. Major processes these units undergo - (1) Screen printing, (2)Manual
>loading of DIPs and Lead frames onto the PCB (3) Reflow Soldering (4)
>Aqueous Cleaning (5) Manual soldering of batteries or crystal on PCB (6)
>Encapsulation - using part A and B epoxy (catalyst and resin) mixed and
>dispensed on a tub (using an encapsulation machine) where the unit will be
>inserted  (7) then cured in the oven for a minimum of 8 hours @ 70ºC.
>
>IF we are to consider that there are no handling issues and machine problem
>-
>a. how do we control this phenomenon?
>b. What are the possible root causes of this phenomenon (wicking or
>capillary effect) during encapsulation process?
>c. How do I know if it is a material problem?
>d. Effects of temperature and humidity on these Lead frames?
>
>
>Any inputs will be highly appreciated.. Thanks.
>
>For your attention:
>
>Eric Lodangco
>FASTECH ADVANCED ASSEMBLY
>Philippines
>

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