Differences

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

--- cleaning [2013/11/17 06:47] – mcmaster
+++ cleaning [2024/06/15 15:24] (current) – polymide -> polyimide (typo) philpem
@@ Line 166: / Line 166: @@
 Shame on you if you picked up a die with your bare hands but things do happen.  Acetone does not clean off fingerprints very well but soapy water does.  The above picture was taken after putting a fingerprint on a slide and sonicating in acetone for a few minutes.  It has little to no effect.  Fingerprint oils do not respond to polarized light (ie will black out).
-===== Polymide passivation =====
-Can be removed with strong acids (eg RFNA).  Still, does not come off easily so other methods should be researched.
+===== Polyimide passivation =====
+General reccomendations:
+  * Oxygen plasma is probably best if you have access to it
+  * If you can deal with safety issues, ethylendiamine may be next best
+  * Fuming nitric aicd works but takes a while.  This can potentially cause chip damage but shouldn't hurt Cu/Al if you keep the concentration high
+  * Piranha eats it quickly but it eats other metals nearly as quickly so its probably best avoided
+==== Ethylendiamine ====
 "find a polyimide layer that was not entirely removed by HNO3 but which can be dissolved with ethylendiamine" ([[http://static.usenix.org/publications/library/proceedings/smartcard99/full_papers/kommerling/kommerling_html/|ref]])
+Rest from [Beck 23]
-==== Ethylendiamine ====
-From [Beck 23]
 Procedure:
@@ Line 185: / Line 188: @@
 ==== Ethylendiamine + hydrazine monohydrate ====
+"Ethylenediamine readily reacts with moisture in humid air to produce a corrosive, toxic and irritating mist, to which even short exposures can cause serious damage to health (see safety)." [Wikipedia]
 From [Beck 23].  Use this if plain ethylendiamine does not work.  Unclear if it has a higher corrosion potential, but heed the safety warning
@@ Line 199: / Line 204: @@
 ==== Ethylendiamine + hydrazine monohydrate ====
+[Beck 23]
 Procedure:
@@ Line 212: / Line 219: @@
 ==== Caro's acid ====
+[Beck 23]
 Procedure:
@@ Line 218: / Line 227: @@
     * 1 mL 30% H2O2
   * Cook at 80° C
+Notes:
+  * Seems like this is same thing as [[Piranha solution]]?  In any case see notes there
 ==== Fuming nitric acid (FNA) ====
-When decapping part with WFNA/RFNA the amide layer will usually be simply dissolved [Beck 26, personal experience]
+When decapping part with WFNA/RFNA the amide layer will usually be simply dissolved [Beck 23, personal experience]
 Beck mentions "imide"?
@@ Line 228: / Line 242: @@
 ==== Oxygen plasma ====
-"Polymides can usually be removed gently without leaving residues by incineration in the oxygen plasma" [Beck 26]
+"Polymides can usually be removed gently without leaving residues by incineration in the oxygen plasma" [Beck 23]
 ==== Dimethyl sulphoxide + ethanolamine ====
+[Beck 23]
 Procedure: