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Introduction
I (JM) would recommend thermal fracture if you are comfortable with a torch.
Thermal fracture
Procedure
Place package on a temperature resistant surface
Heat package with a propane torch until hot, maybe 5 or 10 seconds
Gently splash or sprinkle water on the package. This should create micro-fractures and make it easy to shear
Shear the package open by applying light force. Unlike a non-fractured package this should be possible using simple pairs of pliers or by hand
Tips:
Chip does not have to be heated until red or white hot. Heating this high increases risk to damage the die from glass reflowing as well as general thermal stress
Do not throw the chip into liquid or move it all while it is hot. This can cause the glass to shift and get onto the die
PDIPs should be supported (ie with a block of metal) as the leadframe will become very weak
If it does not shear open the first time try again. Consider increasing heat, pressure, or simply do more runs
Chip before:
No images found.
Advantages:
Disadvantages:
Thermal shock can potentially also break die
High temperatures can warp die
The die is exposed but still in the package
Thermal
Shearing
The glass tends to be much weaker than the ceramic. Therefore, its possible to shear a chip open by moving the top and bottom half in different directions.
Procedure
Place bottom half of package into vice. It may be desirable to put a metal space in between the pins to keep pressure more even
Firmly hold the top of the chip and twist. Keep the movement orthogonal to the glass plane
Ideally this would probably be done using a custom fixture to hold the top and apply even and straight force
Tips
Plumbing wrenches work well to hold the chip as their width can be adjusted for even pressure while still holding it tightly
Be careful with long CERDIPs that you don't apply too much torque on an end and snap the chip in half instead of shear it
Advantages
Disadvantages
Throws debris onto die
Can be difficult to effectively grip top half
Can be difficult to tell how much force is required
Unpredictable how it will shear
Manufacturing
Might provide some hints if we knew how these were produced