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May 2001

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Subject:
From:
"<Peter George Duncan>" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 23 May 2001 17:57:49 +0800
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Morning, All,

I need a quick and general answer to the question "What typically is the
temperture at which components come apart/melt?" My boss asked me how the
use of high melting point (221 deg C) solder would affect components in the
CR Oven, and all I could give him was a fudge answer about thermal profiles
and how even MIL spec devices (rated at 125 deg C) survive 215 deg C+
during soldering with 63/37 solder. Does anyone have an idea of the rough
temperature at which Industrial grade (-40 to +85 deg C) platic-bodied
components fry, and how long it takes to fry them at that temperature?

I had a look through randomly selected component data sheets, but none of
them contained this useful bit of information. They state that if the
maximum case temperature is sustained for an unspecified time, it could
affect the performance and/or reliability of the device, but they advice
was totally non-specific about exactly how much for how long. I experienced
using a component once that had to be manually soldered because it kept
falling apart internally whenever it went near a soldering machine, so I'm
cautious about giving uninformed replies.

I'm trying to solder 35 x 35 mm PBGA's (318 and 388 pins) to an FR4 board
with a finish of 4.5 microinches gold over 150 microinches of Nickel. HMP
solder has been recommended, but the temperature that the boards are
exposed to during soldering goes up by 35 deg C over normal. Your advice,
stories, etc. much appreciated.

Pete Duncan

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