brad@optilink.UUCP (Brad Yearwood) (10/05/89)
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, CAtomcat@cbnewsl.ATT.COM (fred.j.shubert) (10/06/89)
In article <2448@optilink.UUCP>, brad@optilink.UUCP (Brad Yearwood) writes: > 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 Preheat the knife, too. > 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. I've used equipment here at work that costs less than $1K. It uses fuming nitric acid (for aluminum metalization) or sulfuric acid (for gold metal- ization) as each IC uses different metalization and in order to 'decap' the ic without damage you need to use the right acid. The nitric is heated to just under the boiling point and the sulfuric is heated to about 125C. (Something you DEFINATELY don't want to do at home.) I can open up an IC in under a minute with no damage with this stuff and NO grinding is necessary (grinding is stupid as you can damage a wire bond which well exceeds the height of the silicon.). Fred J. Shubert | "You haven't lived until you've seen a 'cat fly!!!" AT&T Bell Labs |----------------------------------------------------- Whippany, N.J. | DISCLAIMER: All views are that of my own. PERIOD. Ma-Bell 201-386-3094 | Who else could be so 'cat crazy!! \ _ / \ /^ ^\ / F-14D ____________\_( . )_/____________ SUPERTOMCATS --*/--|_| (___) |_|--\*-- RULE * O O * (I Love 'Em) Let's turn and burn!!