Differences

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--- cleaning [2013/10/20 14:59] – external edit 127.0.0.1
+++ 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]
+Procedure:
+  * Use straight (how much?)
+  * 100° C for 15-60
+==== 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
+Procedure:
+  * Mix (how much?)
+    * 7 mL 80% hydrazine monohydrate
+    * 1 mL ethylendiamine
+  * 100° C for 15-60?
+Notes:
+  * WARNING: spontaneous combustion can occur over 120° C
+==== Ethylendiamine + hydrazine monohydrate ====
+[Beck 23]
+Procedure:
+  * Mix
+    * 3 mL ethylendiamine
+    * 1 mL 98% acetic acid
+  * Cook 120-130° C for 10-30 minutes
+Notes:
+  * Mix slowly (or what?)
+  * Stir vigorously
+==== Caro's acid ====
+[Beck 23]
+Procedure:
+  * Mix
+    * 7 mL (98%?) H2SO4
+    * 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 23, personal experience]
+Beck mentions "imide"?
+==== Oxygen plasma ====
+"Polymides can usually be removed gently without leaving residues by incineration in the oxygen plasma" [Beck 23]
+==== Dimethyl sulphoxide + ethanolamine ====
+[Beck 23]
+Procedure:
+  * Mix
+    * 3 mL dimethyl sulphoxide
+    * 1 mL part ethanolamine
+  * Cook at 110° C
+WARNING:
+  *  Spontaneous combustion above 120° C