Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!sun-barr!lll-winken!tekbspa!optilink!brad
From: brad@optilink.UUCP (Brad Yearwood)
Newsgroups: sci.electronics
Subject: De-lidding ceramic IC packages (cheap video)
Message-ID: <2448@optilink.UUCP>
Date: 5 Oct 89 05:41:58 GMT
Organization: Optilink Corporation, Petaluma, CA
Lines: 28

It is quite easy to remove the lid from ceramic IC packages which have
a metal cap over the die cavity.  You need an ordinary household electric
stove, tongs or pliers to hold the IC package, and a small spatula or
knife to remove the lid.  Preheat the stove burner (dull red should do),
then place the package upside down on the hot coil in a way that maximizes
contact between the coil and the lid.  The solder holding the lid should
melt in a few seconds.  Then lid can then be slid or lifted off with the
knife.  You must take care to avoid flipping a corner of the lid down
into the die cavity, as the bond wires and die surface are very delicate.

In my experience, RAM chips and an 80186 microprocessor have survived this
treatment.

De-lidded DRAM chips can be a handy source of errors for debugging memory
diagnostics, parity circuits, and software handlers for parity interrupts.
If you're lucky, and DRAMs behave the same way they did when I last tried this,
the de-lidded DRAM will work OK in low light, but will become corrupted when
illuminated with a bright light or an EPROM erase lamp.

If you want to take the "cheap" out of cheap video, there are a couple of
companies selling (for >$10K) nifty little tabletop plasma etchers especially
designed for clean removal of plastic packages.  You remove the bulk of the
plastic by mechanical grinding, then use the plasma etcher to remove the
remaining thin layer and expose the die.

Brad Yearwood
Optilink Corp.  {pyramid, tekbspa, pixar}!optilink!brad
Petaluma, CA