Conformal Coating Woe's

Thread Starter

caddman6425

Joined Mar 23, 2017
17
Here my problem. I've got a PCB that looks like it was dipped in some kid of varnish??? I need to access the pins of the 0D46J chip so I can get the code of the car. Question, does anyone know of a way to get rid of that varnish without unsoldering the chip or destroying it>

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Nick
 

ian field

Joined Oct 27, 2012
6,536
Here my problem. I've got a PCB that looks like it was dipped in some kid of varnish??? I need to access the pins of the 0D46J chip so I can get the code of the car. Question, does anyone know of a way to get rid of that varnish without unsoldering the chip or destroying it>

--
Nick
Any solvent strong enough to shift the varnish will also shift the numbers, unless they're laser cut.

Sometimes thick varnish can be pried off once you find a weak spot, if you have anything more precise than a scalpel - now is the time. If you can't pry it off, maybe you can clean it up and get some semblance of "optical" by lapping it on *VERY* fine wet or dry paper.

Thin varnish makes it easier to take the numbers with it - try light and magnification while everyone tries to come up with a new trick.
 

Reloadron

Joined Jan 15, 2015
7,580
You may want to give this a read; Coating Removal, Solvent Method.

Pay close attention to the part about; To determine the appropriate coating removal procedure the coating must first be identified. You really need to identify the exact coating before you go ballistic with solvents trying to remove it. Over the years I worked with some very good gels but they were also caustic and required some prep before and after use on boards.

Ron
 

#12

Joined Nov 30, 2010
18,224
I have gotten away with re-soldering a lot of chips on a coated board because the temperature of melting solder destroys the coating. This coating is intended to stop you from gaining access, so it's all, "At your own risk". Be careful, and good luck!
 

Thread Starter

caddman6425

Joined Mar 23, 2017
17
Ian Field
What is ment by
Any solvent strong enough to shift the varnish will also shift the numbers, unless they're laser cut.
 

Thread Starter

caddman6425

Joined Mar 23, 2017
17
Sorry guys, not used to the forum yet. I've been given a BMW 740iL with a key fob that doesn't work, so I took out the immobilizer so I could get to the 0D46J chip, which holds the rolling code that the transponder interrupts. I can get this code from my key programmer by clamping the receptacle socket over the 0D46J chip and reading the code. Can't do it cause of the varnish, and I need to read that chip the Varnish is brown and thick. All I wanted to know is what I could use to get it off without destroying the chip. Sorry that I displayed that I was an idot

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Nick

PS
Don't use Google to talk, I can make an idol out of myself with out it.
 

AlbertHall

Joined Jun 4, 2014
12,396
I can get this code from my key programmer by clamping the receptacle socket over the 0D46J chip and reading the code. Can't do it cause of the varnish, and I need to read that chip the Varnish is brown and thick.
Probably your best bet to clear the varnish off the chip connections is with a soldering iron. Just don't keep it on the joint for too long and let it cool down between each pin.
 

ian field

Joined Oct 27, 2012
6,536
Ian Field
What is ment by
Any solvent strong enough to shift the varnish will also shift the numbers, unless they're laser cut.
I misread "getting the code off the chip" as trying to read its number.

If you want to get at the pins, a fibre abrasive pencil might do it - but it'll destroy the fiber insert, they're not too expensive consumables though.

Fine-ish abrasive paper also works - as long as you're dead careful with fine pitch pins.
 

Thread Starter

caddman6425

Joined Mar 23, 2017
17
I don't know what to do. The key is crushed but the key programmer/extractor can read the key, which doesn't make any sense, since when I save the bin code and try to burn another key, it won't. I've melted off the varnish off the pins and erased the pins, but I still get a "No Pin Touch" condition. I don't know what is wrong and what to do next. Heck, I don't even know what chip it is, all I know is that it reads 0D46J.
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Nick
 

ian field

Joined Oct 27, 2012
6,536
I don't know what to do. The key is crushed but the key programmer/extractor can read the key, which doesn't make any sense, since when I save the bin code and try to burn another key, it won't. I've melted off the varnish off the pins and erased the pins, but I still get a "No Pin Touch" condition. I don't know what is wrong and what to do next. Heck, I don't even know what chip it is, all I know is that it reads 0D46J.
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Nick
Its probably some kind of flash micro - and even more probably has the security bit set.
 

Thread Starter

caddman6425

Joined Mar 23, 2017
17
That what I'm trying to do. I've got a new key that isn't cut, or programed. I've got an AK90+ programmer, but I can't seem to read the eprom in the Immobilizer, but I can read the destroyed key. Things just don't seem correct. Does anyone know what chip is in the Immobilizer, the numbers are as follows:
PM-FT
XC93222CFN
0D46J
NMQQTT0017
 
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