Differences

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

--- bonding:removal [2020/04/30 22:36] – [Gold wood's metal] mcmaster
+++ bonding:removal [2020/10/25 06:06] (current) – mcmaster
@@ Line 14: / Line 14: @@
   * Gold wire: use mercury or shear
   * Copper wire: moderate strength nitric acid (say 50%)
+-10-24: I've had good luck with swab method. It might see more use moving forward
 ====== Mechanical methods ======
+===== Swab =====
+I've had good luck removing bond wires using optical cleaning swabs. They are soft and don't damage the die surface, but bond wires tend to get caught on them. This allows bond wires to be quickly pushed off without scratching the die. In theory the gold could scratch the surface, but as long as light pressure is used they shouldn't be able to press in
 ===== Ultrasound =====
@@ Line 62: / Line 68: @@
 ===== Gold I/NaI  =====
-https://twitter.com/lukeweston/status/1253256917457137664?s=20
+TLDR: not recommended. Eats aluminum
+  * Details w/ references: https://twitter.com/johndmcmaster/status/1256773931807043585
-Mix
+https://twitter.com/lukeweston/status/1253256917457137664?s=20
   * 2.5 g I
   * 10 g NaI
   * 100 mL H2O
+https://www.inrf.uci.edu/wordpress/wp-content/uploads/sop-wet-gold-etch-using-potassium.pdf
+  * 0.5 – 1 um/min at room temperature
+  * mix
+    * 1 g I2 (solid)
+    * 4 g KI (solid)
+    * 40 ml DI water
+  * glass or poly bottle
+https://www.sigmaaldrich.com/catalog/product/aldrich/651818?lang=en&region=US
+  * Etch rate of 28 angstrom/sec @ 25 °C.
+  * Synonym: Antistrumin, Potassium monoiodide
+http://engineering.tufts.edu/microfab/documents/sop_goldetch.pdf
+  * Has temp etch curve
+  * 30C: 400 um / min
+  * 45C: 800 um / min
+  * 60C: 1500 um / min
 ===== Gold NaCN =====
@@ Line 96: / Line 121: @@
 Move to PTFE watch glass + heatgun from solder pot
+Notes
+  * teflon melting point 620F (327C)
+  * 770F heatgun => 415F blob?
+  * 2020-05-04: 770F => 441F measured
+  * 60/40 melts around 190C => 374F
 ===== Gold lead =====