Differences

This shows you the differences between two versions of the page.

--- decap:ceramic_glass [2012/01/29 00:10] – mcmaster
+++ decap:ceramic_glass [2016/12/03 20:50] (current) – removed mcmaster
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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
-===== Media =====
-Chip before:
-{{:decap:ceramic_glass:before.jpg|}}
-Advantages:
-  * Can be very clean and low risk
-Disadvantages:
-  * Thermal shock can potentially also break die
-  * High temperatures can warp die
-  * The die is exposed but still in the package
-====== Thermal  ======
-Advantages
-  * Can completely remove a die
-Disadvantages
-  * Removed dies still may have an uneven bottom.  This can be solved by very carefully heating them on a surface that glass won't stick to until the glass melts
-====== 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
-  * Very readily available materials
-  * Does not use any consumables
-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