Whatever happened to the Flat-Pack (was Re: Discontinued IC's)

From: Chris Kennedy <chris_at_mainecoon.com>
Date: Mon Jul 31 17:27:46 2000

CLASSICCMP_at_trailing-edge.com wrote:

> Whatever happened to the flat-pac? It seems to me to be a package that
> has many of the same advantages of modern SOIC's, but maybe 30 years ahead
> of its time. Was it a manufacturability issue? Was it a "proprietary"
> issue? The flat-pacs I worked with were ceramic or ceramic/gold, but it
> seemed pretty straightforward to me to do the same thing with plastic. Am
> I wrong?

I don't know. They were clearly harder to handle than DIPs, and in
a weird twist they were actually harder to use than DIPs in some military
applications where the enclosure had to be sealed in order to meet
corrosion, fungus or altitude MilSpecs. In such cases the common
approach was to straddle thermal frames with DIPs and use the thermal
frame to conduct the heat to the sides of the enclosure and then design
the enclosure itself to get rid of the heat. The ME types always told
me that this was easier to do with DIPs than with flat-packs, but I
was never clear why a frame bolted on top of a flat-pack was inferior
to a DIP straddling the frame. There was also an assertion that
for this reason flat-packs were generally used in short-life
applications, such as seeker or guidance electronics, but I have
no evidence to suggest that this was anything more than legend.
Chris Kennedy
PGP fingerprint: 4E99 10B6 7253 B048 6685  6CBC 55E1 20A3 108D AB97
Received on Mon Jul 31 2000 - 17:27:46 BST

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