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equipment:storage [2018/12/17 04:33] – [Blue tape] mcmaster | equipment:storage [2021/12/09 05:48] (current) – mcmaster | ||
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====== Foams ====== | ====== Foams ====== | ||
+ | |||
+ | ===== Brands ===== | ||
+ | |||
+ | ^ Image ^ Vendor | ||
+ | | | All-Spec | ||
+ | | | All-Spec | ||
+ | | | Zoro | [[https:// | ||
+ | | | eBay | | 1/2" x 15.5" x 11.75" | ||
+ | |||
+ | 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 | ||
+ | |||
+ | {{: | ||
+ | |||
+ | 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 | 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 | ||
+ | |||
+ | < | ||
+ | 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 ' | ||
+ | </ | ||
+ | |||
+ | [Lord_Nightmware IIRC] | ||
+ | |||
+ | < | ||
+ | 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:// | ||
+ | https:// | ||
+ | </ | ||
+ | |||
+ | [[https:// | ||
+ | |||
+ | |||
+ | 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]: | Terms [Foam vs]: | ||
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* Anti-static: | * Anti-static: | ||
- | ===== Density ===== | + | Typically ESD bags are aluminum coated mylar. Pink bags are dissipative, |
- | Vendors talk about low and high density foams. | ||
- | + | ==== 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. | ||
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- | ===== Blue foam ===== | + | ==== Blue foam ==== |
Like above, but less sensitive to moisture [Why pink]. | Like above, but less sensitive to moisture [Why pink]. | ||
- | ===== Black foam ===== | + | ==== Black foam ==== |
From private communication (speculative but may be good lead): | From private communication (speculative but may be good lead): | ||
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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. | ||
+ | |||
+ | |||
+ | ===== 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. | ||
+ | |||
+ | |||
+ | ====== Label ====== | ||
+ | |||
+ | DIP14 (0.3") | ||
+ | * 6 mm | ||
+ | * 9 pt | ||
+ | |||
+ | DIP28 (0.5") | ||
+ | * 12 mm | ||
+ | * 9 pt | ||
+ | |||
+ | DIP40 (0.5") | ||
+ | * 12 mm | ||
+ | * 5.0" | ||
+ | * 9 pt | ||
====== References ====== | ====== References ====== |