Differences

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

--- decap:ceramic [2019/12/09 07:30] – [Top heat] mcmaster
+++ decap:ceramic [2020/10/21 22:24] (current) – [Glass frit] mcmaster
@@ Line 25: / Line 25: @@
 ====== Glass frit ======
+-10-21
+  * General consensus may be that heating to below melting point (softens but doesn't liquefy glass) followed by shearing may be the best approach for most
+  * Mind heat and cool cycles to avoid thermal shock
 JM 2016-11 advice:
@@ Line 91: / Line 95: @@
 ===== Bandsaw =====
+{{:mcmaster:decap:ceramic:bandsaw_sample.jpg?400|}}
+Above: fixturing for cutting. Sample held in DIP 40 ZIF. Use cross slide to stablize.
+{{:mcmaster:decap:ceramic:decap_saw_cut.jpg?400|}}
+Above: cuts on far sides of cavity. They are above wires but not the die
+{{:mcmaster:decap:ceramic:decap_saw_tape.jpg?400|}}
+Above: tape placed to keep lid in place as its sheered off. Excessive movement may damage bond wires. Tape also helps retain large pieces if it fractures.
+{{:mcmaster:decap:ceramic:decap_saw_peel.jpg?400|}}
+Above: lid peeled off after sheering
 DB-100 diamond bandsaw
-TLDR:
+-12-16 procedure for large ceramic packages:
-  * Saw a small hole in one side of the cavity above bond wires
+  * Place chip in DIP-40 socket to help steady during cutting
+  * Saw a slit on both sides of the cavity
+    * As far as possible, usually about 0.1" after the quartz window
+    * Saw just into the glass frit
+      * WARNING: failing to completely separate ceramic can lead to unpredictable breakage
+    * Should be roughly above where the bond wires attach but not above the die
+    * Small debris in the cavity is normal and shouldn't hurt the die
+    * Pins make good guides. I usually saw between two
   * Fill with nail polish to help protect the die against debris
+    * Use a small pipette to pump it into the cavity from one side
+    * Should push out any water from sawing
+  * Alternatively, for small packages it may make sense to simply grind (see below)
+  * Place in vice with top cavity just above jaws
+  * Place tape over top of package
+  * Gently tap side of lid with chisel to sheer it
+  * Peel away tape and lid together
+  * Wash nail polish away with acetone
+    * See UV masking page for more info
+Grinding:
+  * Grinding was used more initially, but can be slower (especially for large packages) and may have increased change to damage die
+  * Alternate side of blade used to prolong blade life
   * Slowly side grind and/or cut across the whole cavity
-    * Cut about halfway through the top ceramic
+  * Cut about halfway through the top ceramic
     * You shouldn't need to go all the way to the frit
+  * Try to make one continuous cut
+    * Multiple cuts increase change to fragment and create larger debris
   * Wash nail polish away with acetone
     * See UV masking page for more info