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--- equipment:storage [2018/12/17 03:59] – mcmaster
+++ equipment:storage [2020/11/22 04:11] – [Table] mcmaster
@@ Line 149: / Line 149: @@
 ===== Blue tape =====
-Diced wafers are usually on blue tape.  Thin plastic films should stick easily to seal it up.
+Diced wafers are usually on blue tape.  Thin plastic films should stick easily to seal it up. I've been cutting the edges off to make them non-sticky and putting them in standard wafer carriers.
 ===== Vacuum pack =====
@@ Line 165: / Line 163: @@
 ====== Foams ======
+===== Brands =====
+^ Image  ^ Vendor    ^ Model                                                                                                               ^ Size                   ^ Cell    ^ Density lb/ft3        ^ Tensile Strength PSI  ^ Color  ^ mcmaster\\ bag  ^ mcmaster\\ bag each       ^ mcmaster\\ bag lg  ^ mcmaster\\ bag lg each    ^ DIP usable?   ^ Notes                                                          ^
+|        | All-Spec  | [[https://www.all-spec.com/Catalog/Static-Control/ESD-Safe-Cushioning-Materials/ESD-Safe-Foams/713-2935|713-2935]]  | 3/8 x 29 x 35"         | Closed  | 50kg/m³               | 515KPa                | Black  | Cut: 7-1/2      | $33.60/(3*4)\\ $2.80/sht  | Cut ~8.5           | $33.60/(3*4)\\ $2.80/sht  | Yes           | "Non-staining, non-corrosive"\\ "Closed cell - non-absorbent"  |
+|        | All-Spec  | [[https://www.all-spec.com/Catalog/Static-Control/ESD-Safe-Cushioning-Materials/ESD-Safe-Foams/750-2436|750-2436]]  | 1/2 x 24 x 36"         | Closed  | 1.8 pcf (28.8 kg/m3)  | 31 PSI (215kPa)       | Pink   | Cut: 7-5/8      | $17.61/(3*4)\\ $1.47/sht  | Cut ~8.5           | $17.61/(2*4)\\ $2.20/sht  | Yes           | Ethafoam 180 as                                                |
+|        | Zoro      | [[https://www.zoro.com/zoro-select-foam-sheet-36-l-36-w-38-pink-5gdc4/i/G1112921/|G1112921]]                        | 3/8 x 36 x 36"         | Open    | 1.4 lbs. cu. ft       | 13 PSI                | Pink   | N/A             |                           |                    |                           | No: too soft  |                                                                |
+|        | eBay      |                                                                                                                     | 1/2" x 15.5" x 11.75"  |         |                       |                       |        |                 | $1.30/(2*1)\\ $0.65/sht   | Cut 9-5/8          | $1.30/(1*1)\\ $1.30/sht   |               |                                                                |
+/8" (10 mm) thick seems to work well for putting DIPs on both sides. However, 1/2" (12mm) was easier to source at the time
+{{:mcmaster:foam:cut_foam.jpg?400|}}
+mcmaster bags: U-Line S-3704 (pink, 8x8"). Fits nicely into divided boxes.
+===== Degradation =====
 This section was added to try to learn why some black conductive foams degrade into powder and others degrade into a (mildly corrosive?) sticky mess
+<code>
+depends on whether you want your foam to turn to goo or powder. personally i prefer goo
+powder is open cell foam, it works as an abrasive too
+goo is closed cell foam, which is oddly slick
+after 20 years the foams disintegrate
+open cell foam turns into some sort of acid (acetic?) which will eat chip legs i think
+i don't know about closed cell
+i think closed cell disintegrates much slower but gets 'sticky'
+</code>
+[Lord_Nightmware IIRC]
+<code>
+The open cell foam is very likely polyurethane foam†, which degrades into a powder
+(clumps if compressed) primarily via hydrolysis / photo-oxidation depending on the type¹
+and (assuming polyester-based PU) releases mainly adipic acid, which is corrosive².
+†) general consideration of properties, and a few very rough tests such as:
+heating (chars: thermoset polymer), comparison against known PU foam; with supportive results.
+https://sci-hub.tw/10.1016/j.chroma.2011.05.013
+https://sci-hub.tw/10.2307/20619421
+</code>
+[[https://twitter.com/0Ekho/status/1147145691417853954|Source]]
+Repairing: mcmaster cleans up pins using glass fiber brush then briefly soaks in HCl. Finally, use liquid tin to re-plate
+===== Conductivity =====
 Terms [Foam vs]:
@@ Line 174: / Line 219: @@
   * Anti-static: inhibits triboelectric charging, "the buildup of an electric charge by the rubbing or contact with another material"
-===== Density =====
+Typically ESD bags are aluminum coated mylar. Pink bags are dissipative, while blue bags offer no protection, but don't generate static. Do foams carry the same convention?
-Vendors talk about low and high density foams.  There doesn't seem to be any agreement whatsoever as to what these mean, even within the same vendors.  Look at the kg/m3 ratings I guess if you care about density
+==== Pink foam ====
-===== Blowing agent =====
-In order to turn a liquid into a foam, you need a way to aerate it.  Looks like traditionally this was done with CFCs but looks like it may now typically be done with nitrogen.
-===== Pink foam =====
 Also seen in the form of bags and packing bubbles.
@@ Line 206: / Line 244: @@
-===== Blue foam =====
+==== Blue foam ====
 Like above, but less sensitive to moisture [Why pink].  Unclear if it has any disadvantages (cost, lifetime, etc)
-===== Black foam =====
+==== Black foam ====
 From private communication (speculative but may be good lead):
@@ Line 223: / Line 261: @@
 Maybe could UV irradiate foam to simulate aging
+===== Density =====
+Vendors talk about low and high density foams.  There doesn't seem to be any agreement whatsoever as to what these mean, even within the same vendors.  Look at the kg/m3 ratings I guess if you care about density
+===== Blowing agent =====
+In order to turn a liquid into a foam, you need a way to aerate it.  Looks like traditionally this was done with CFCs but looks like it may now typically be done with nitrogen.
 ====== References ======