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| bonding:rebond [2015/12/17 23:35] – azonenberg | bonding:rebond [2019/03/05 00:16] (current) – removed mcmaster | ||
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| - | It is often necessary to re-bond a bare die. Typical reasons include: | ||
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| - | * Original bond wires were accidentally destroyed during decap | ||
| - | * Device was obtained as a bare die from a third party | ||
| - | * FIB edit could not be done with device in package due to mechanical constraints | ||
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| - | Several firms sell refurbished wire bonders and provide service, support, and parts. Some of these companies will also do custom bonding projects for single dies or small lots. | ||
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| - | ====== Surface preparation ====== | ||
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| - | If any existing bonds, or pieces of them, are still on the pads these must be [[bonding: | ||
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| - | Pads should be [[: | ||
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| - | FIXME: Get a photo of a nice clean pad that copper bond wire was etched off of | ||
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| - | ====== Mounting ====== | ||
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| - | The die must be secured firmly to its new package to keep it from moving around. AZ has had good experiences using a tiny dot of cyanoacrylate adhesive, although silver epoxy or Crystalbond would likely work fine as well. Make sure the volume of adhesive is low enough that it doesn' | ||
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| - | {{: | ||
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| - | ====== Re-bonding ====== | ||
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| - | Bonding to a clean, once-bonded pad should be essentially the same as bonding to a never-bonded pad. Contact resistance may be a little higher and reliability reduced, but this isn't a big concern if you just want to dump the firmware. | ||
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| - | ====== Bondable materials ====== | ||
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| - | Bondable surfaces are generally soft metals with minimal oxidation (thin native oxide will be penetrated by the " | ||
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| - | * **Aluminum bond pads**\\ Good results as long as bond wires were removed cleanly | ||
| - | * **Copper bond pads**\\ AZ has no experience with these | ||
| - | * **Bare copper PCB surface** AZ had issues due to oxidation on a board that had been sitting around for a while. After sanding the surface with 450 grit paper it was too rough for bonds to stick. Further research needed. Copper SEM mounting tape didn't seem to work either. | ||
| - | * **Gold plated CERDIP pads** \\ Good results | ||
| - | * **ENIG PCB finish** This is not normally considered a bondable material (50-125 nm of Au, typical " | ||
| - | * **Pb HASL** Not bondable under any process parameters tested. First bond sometimes sticks but second lifts up during tear-off. | ||
| - | * FIXME: Try bonding to FIB deposited Pt | ||
| - | * FIXME: Try bonding to FIB deposited W | ||
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| - | ====== Tool-specific notes ====== | ||
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| - | * [[ks4522|K& | ||
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| - | ====== Commercial companies / other resources ====== | ||
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| - | http:// | ||
| - | * Mechanically removes bond wires | ||
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| - | http:// | ||
| - | * Wick solder bumps to gold surface | ||
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