Differences

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--- decap:ceramic_glass [2012/07/22 01:25] – mcmaster
+++ decap:ceramic_glass [2016/12/03 20:49] – mcmaster
@@ Line 1: / Line 1: @@
-====== Package ======
+JM 2016-11 advice:
+  * Use "Top Heat (gentle)" for safest result
+  * Use "Top Heat (quick)" for less safe but cleaner result
-I (JM) would recommend thermal fracture if you are comfortable with a torch.
-===== Thermal fracture =====
+===== Top heat =====
+Gentle procedure:
+  - Place chip into heat spreader block
+  - Place chip + spreader into vice
+  - Torch heat spreader
+    * DIP28: ~10 seconds
+    * DIP40: ~20 seconds
+  - Begin torching top of chip
+    * Use the side of the flame, not the tip, for gentler and more even heating
+  - Every 5-10 seconds try to pry lid up.  If it is starting to budge, immediately do the next few steps
+  - Stop torching
+  - Gently pull lid up and over chip, hinging on the far side
+  - Separate lid from package
+{{:mcmaster:decap:glass_frit:quick_before.jpg?300|}}
+{{:mcmaster:decap:glass_frit:quick_after.jpg?300|}}
+Above: sample quick result
+Quick procedure:
+  - Place chip into heat spreader block
+  - Place chip + spreader into vice
+  - Begin torching top of chip
+    * Side or tip of flame better?
+  - Every 5-10 seconds try to pry lid up.  If it is starting to budge, immediately do the next few steps
+    * Listen for a small popping noise.  This usually indicates the lid has sheared from the frit and can be easily removed, possibly with slightly more heat
+    * If its not the lid, the package has probably cracked
+  - Stop torching
+  - Gently pull lid up and over chip, hinging on the far side
+  - Separate lid from package
+General notes:
+  * Wave torch back and forth to keep heat even
+  * FIXME: torch model I use
+  * DO NOT torch while lid is lifting.  Will quickly destroy bond wires
+  * Heat spreader can be aluminum or steel
+    * Steel won't be melted by propane torch
+    * Aluminum can melt if abused, but will conduct heat better
+  * If the package cracks, finish procedure and then assess damage.  The spreader should keep package integrity until assessment is done.  If the die cracks, the chip is probably a loss
+===== Thermal fracture (old) =====
 Procedure
@@ Line 99: / Line 143: @@
 ===== Dissolve =====
+% HNO3 is known to dissolve the frit.  However, it would probably dissolve other things (ie the pins) as well
 It should be possible to use HF to dissolve the ceramic.  Maybe NaOH could work as well?
+===== References =====
+http://www.freepatentsonline.com/4992628.html
+http://www.ti.com/lit/an/snoa280/snoa280.pdf