Is it possible to debayer a sensor using chemicals? - Page 1
Forum section: electronics / projects

author: Logan
author_rank: Frequent Contributor
timestamp: September 28, 2021, 03:32:09 pm
content: Hi guys.I see many people remove the bayer filter by scratching the surface of CCD/CMOS, but that's very risky and have a low rate of success without at least partially damage the sensor. I wonder if there's any chemical (maybe solvents like acetone) that will dissolve the bayer later but not harming other things?Thanks.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: September 28, 2021, 04:13:49 pm
content: The short answer is yes, but not with chemicals you want to use. Think aggressive and carcinogenic dichromate mixtures. There's also much danger of wrecking the bond wires, so you might need a wire bonder to fix it. I don't know if different manufacturers use different materials that might require different methods.

author: Marco
author_rank: Super Contributor
timestamp: September 28, 2021, 05:20:21 pm
content: Why not just use hot sulfuric same as decapping?

author: magic
author_rank: Super Contributor
timestamp: September 28, 2021, 07:33:28 pm
content: Is there no protective glass cover on those things that would thwart most chemical attacks?

author: Whales
author_rank: Super Contributor
timestamp: September 28, 2021, 10:28:13 pm
content: An alternative is laser debayering which trades the hazardous chems for hazardous lasers. I have no idea about the relative costs.

author: Marco
author_rank: Super Contributor
timestamp: September 28, 2021, 11:08:43 pm
content: Find some mobile repair shop with one of those laser machines to carbonize the glue behind glass backs and ask them to do it?

author: bson
author_rank: Unknown
timestamp: September 29, 2021, 02:43:40 am
content: Can't it be removed with some judicious polishing? Like a Dremel with a polishing wheel or cylinder and a suitable polishing compound.

author: Someone
author_rank: Super Contributor
timestamp: September 29, 2021, 05:15:23 am
content: To add to the sensible voices above: the colour filters (CFA) in a modern image sensor are integral or so closely coupled with the micro lenses you'll kill the sensors optical performance by removing them.

author: magic
author_rank: Super Contributor
timestamp: September 29, 2021, 05:28:40 am
content: Apparently OP is right and "debayering" sensors is a thing. Of course any glass, AA/IR filters, etc. need to be removed first, which may pose a challenge in itself if they are glued well.Regarding chemical methods, I found this:https://www.cloudynights.com/topic/719093-chemically-stripping-bayer-matrix-and-microlenses-from-a-canon-sensor/It looks like yet another instance of a recurring problem: how do I get rid of some epoxy resin or similar thing. There are many such resins, they are all quite tough, results vary. NMP may or may not work, as above. Perhaps DMSO, formic or acetic acid, DCM - particularly with elevated temperature or prolonged exposure. Acetone, MEK or alcohols are pretty much guaranteed to do nothing at all.More reliable agents are indeed acids: fuming nitric, 68% nitric (near boiling temperature of ~130°C) and 95~98% sulphuric (may require ~200°C). These destroy even IC packages, which are some of the toughest epoxies around.Acids tend to attack metals to a varying degree. Perhaps it wouldn't me as much of a problem with BSI sensors if there are no electronics on the active side. 68% nitric is particularly bad, FNA is the least corrosive, possibly followed by a mixture of conc. sulphuric and nitric at a moderate temperature, but that's dangerous stuff which will set on fire or explode many combustible materials/chemicals including common solvents and possibly some lab gloves.Goes without saying that anything that attacks the color filter will also attack many other plastics, PCB material, etc.

author: Marco
author_rank: Super Contributor
timestamp: September 29, 2021, 03:31:12 pm
content: Quote from: magic on September 29, 2021, 05:28:40 amThe pulse laser has the advantage here, it will decompose the glue and the filter right through glass. That's why they use them for mobile phones.

author: coppercone2
author_rank: Super Contributor
timestamp: October 01, 2021, 02:59:16 pm
content: try nitro-alcohols to dissolve epoxy, i.e. nitromethane. I use nitroethane to undo epoxy on optical threaded assemblies that is used as a threadlocker. Expensive though.There is also THF that is amazing on cleaning superglue.. not sure what it does to epoxy.Stay away from chromates, acids are toxic and dangerous in their own right but chromate is the bad kind of poison that you don't want around. Acid will just burn you unless you get severe exposure to fumes.. the point is its obvious, painful and you wash it off and get proper help if there is a problem, but chromate is an actual poison with delayed effects etc.

author: Marco
author_rank: Super Contributor
timestamp: October 01, 2021, 04:29:30 pm
content: Nitromethane used to be cheap and readily available for model airplanes, depending on your country it might still be. Anti-terrorism laws might have made selling it pure too much of a pain though in some countries.