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| decap:epoxy_acid [2021/12/29 20:01] – mcmaster | decap:epoxy_acid [2023/11/18 11:49] (current) – [References] philpem | ||
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| - Optional: mill out a cavity about the size of the die | - Optional: mill out a cavity about the size of the die | ||
| - Place IC in petri dish on hot plate | - Place IC in petri dish on hot plate | ||
| - | - Heat to 150C | + | - Heat hot plate to 100C |
| - Place one drop of FNA (possibly mixed with concentrated sulfuric) on center of chip | - Place one drop of FNA (possibly mixed with concentrated sulfuric) on center of chip | ||
| - Wait a few seconds | - Wait a few seconds | ||
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| Low cost technique using readily available materials. | Low cost technique using readily available materials. | ||
| - | Procedure | + | Sample procedure |
| - Heat bath to desired temperature | - Heat bath to desired temperature | ||
| - | * The solution will start forming black whisps when it reaches minimum temperature. | + | * TLDR: 200C is a good starting point |
| - | - Cook until done. | + | - Cook until done |
| + | * TLDR: check every 15 minutes at 200C | ||
| + | * Time varies greatly with temperature, epoxy type, and thickness | ||
| + | * Solution opaque => difficult to monitor. You might need to pour to another container to check | ||
| + | * That said, probably on the order of 10s of minutes for 200C | ||
| + | * 350C will take seconds even for a thick chip | ||
| + | - Pour off as much acid as possible and then rinse chip in acetone | ||
| Notes | Notes | ||
| * Temperature | * Temperature | ||
| + | * The solution will start forming black whisps in solution when it reaches minimum temperature. | ||
| * Higher temperatures make it go faster. | * Higher temperatures make it go faster. | ||
| * At about 300C fumes are a huge problem but I did decap a large plastic chip in about 10 seconds | * At about 300C fumes are a huge problem but I did decap a large plastic chip in about 10 seconds | ||
| * It may work best to reflux the acid as it will boil off rapid above about 275. I use a watch glass to cover the beaker which helps considerably and is easy | * It may work best to reflux the acid as it will boil off rapid above about 275. I use a watch glass to cover the beaker which helps considerably and is easy | ||
| - | * Water severely reduces effectiveness. | + | * Water severely reduces effectiveness |
| + | * Use acetone instead of water if possible | ||
| + | * If a chip is inspected and washed | ||
| * I put chips into a PTFE basket (drilled out smaller beaker) so that they can be quickly removed and inspected without cooling down the acid bath | * I put chips into a PTFE basket (drilled out smaller beaker) so that they can be quickly removed and inspected without cooling down the acid bath | ||
| - | * As the acid concentration drops it begins to boil up. This is extremely dangerous and can lead to boiling over. Mitigation: | + | * As the acid concentration drops it begins to boil up. This is extremely dangerous and can lead to boiling over |
| + | * Ideally | ||
| + | * Using big beakers | ||
| {{: | {{: | ||
| * Sulphuric eats most metals, although slowly. Expect pins and such to still be in tact, but the bond wires will likely break without any support | * Sulphuric eats most metals, although slowly. Expect pins and such to still be in tact, but the bond wires will likely break without any support | ||
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| ====== References ====== | ====== References ====== | ||
| * http:// | * http:// | ||
| - | * CDCA: http:// | + | * CDCA: 403 errors (as of Nov 2023), archived in Wayback Machine: http:// |
| + | * Original URL: http:// | ||