[[equipment:storage]]
 
Trace:

Differences

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

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision		Previous revision
Last revisionBoth sides next revision
equipment:storage [2019/07/05 18:23] – mcmasterequipment:storage [2020/11/22 04:11] – [Table] mcmaster
Line 164: Line 164:
 ====== Foams ====== ====== Foams ======
  
-3/8" (10 mm) thick seems to work well for putting DIPs on both sides+===== Brands =====
  
-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+^ 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   |               |                                                                |
  
-Terms [Foam vs]: +3/8" (10 mm) thick seems to work well for putting DIPs on both sides. However, 1/2" (12mm) was easier to source at the time
-  * Conductive: surface resistance < 1 x 10 5 ohms/square +
-  * Dissipative: 1 x 10 5 ohms/square < surface resistance < 1 x10 11 ohms/square +
-  * Insulative: surface resistance > 1 x 10 12 ohms/square +
-  * Anti-static: inhibits triboelectric charging, "the buildup of an electric charge by the rubbing or contact with another material"+
  
 +{{: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> <code>
 depends on whether you want your foam to turn to goo or powder. personally i prefer goo depends on whether you want your foam to turn to goo or powder. personally i prefer goo
-14:57:57 powder is open cell foam, it works as an abrasive too +powder is open cell foam, it works as an abrasive too 
-14:58:07 goo is closed cell foam, which is oddly slick +goo is closed cell foam, which is oddly slick 
-14:58:23 after 20 years the foams disintegrate +after 20 years the foams disintegrate 
-14:58:41 open cell foam turns into some sort of acid (acetic?) which will eat chip legs i think +open cell foam turns into some sort of acid (acetic?) which will eat chip legs i think 
-14:58:45 i don't know about closed cell +i don't know about closed cell 
-14:58:56 i think closed cell disintegrates much slower but gets 'sticky'+i think closed cell disintegrates much slower but gets 'sticky'
 </code> </code>
  
-<code> +[Lord_Nightmware IIRC]
-https://twitter.com/0Ekho/status/1147145691417853954+
  
 +<code>
 The open cell foam is very likely polyurethane foam†, which degrades into a powder 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 (clumps if compressed) primarily via hydrolysis / photo-oxidation depending on the type¹
Line 200: Line 206:
 </code> </code>
  
 +[[https://twitter.com/0Ekho/status/1147145691417853954|Source]]
  
-== Brands == 
  
-https://www.zoro.com/zoro-select-foam-sheet-36-l-36-w-38-pink-5gdc4/i/G1112921/ +Repairing: mcmaster cleans up pins using glass fiber brush then briefly soaks in HCl. Finally, use liquid tin to re-plate
-  * Too low density to be useful +
-  * Open cell +
-  * Density: 1.4 lbs. cu. ft +
-  * Tensile Strength (PSI): 13+
  
-https://www.all-spec.com/Catalog/Static-Control/ESD-Safe-Cushioning-Materials/ESD-Safe-Foams/750-2436 +===== Conductivity =====
-  * Advertises for chips +
-  * Closed cell +
-  * Density: 1.8 pcf (28.8 kg/m3) +
-  * Tensile Strength: 31 psi (215kPa)+
  
-https://www.all-spec.com/Catalog/Static-Control/ESD-Safe-Cushioning-Materials/ESD-Safe-Foams/713-2935 +Terms [Foam vs]: 
-  * "For Use With: Pin Insertion" +  * Conductive: surface resistance < 1 x 10 5 ohms/square 
-  * Density: 50kg/m³ +  * Dissipative: 1 x 10 5 ohms/square < surface resistance < 1 x10 11 ohms/square 
-  * Tensile Strength: 515KPa+  * Insulative: surface resistance > 1 x 10 12 ohms/square 
 +  * 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. Also seen in the form of bags and packing bubbles.
Line 252: Line 244:
  
  
-===== Blue foam =====+==== Blue foam ====
  
 Like above, but less sensitive to moisture [Why pink].  Unclear if it has any disadvantages (cost, lifetime, etc) 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): From private communication (speculative but may be good lead):
Line 269: Line 261:
  
 Maybe could UV irradiate foam to simulate aging 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 ====== ====== References ======
 
equipment/storage.txt · Last modified: 2021/12/09 05:48 by mcmaster
 
Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution 4.0 International
Recent changes RSS feed Donate Powered by PHP Valid XHTML 1.0 Valid CSS Driven by DokuWiki