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Subject: RE: [Homebrew_PCBs] Re: Chemical question

From: Dennis Shelgren <nojoeco@...>
Date: 2017-08-27

Long ago I worked at Intel in "package, noise, and thermal". We had a bunch of companies demo their individual products for finding hot spots, shorts, etc. 
One of the companies had a liquid crystal system. There were different ways to apply it, and it was actually pretty neat to use. Of course the quicker the process and more temperature zones we needed the more expensive it got. For the boards we were working with, we actually had to "paint" it in zones, i.e. broad temperature over most of the board, high temperature on 3 chips, and then some sensitive formula where needed. 
Although it was cheaper than a thermal camera up front, we had to do a ton of prep work each board. Afterward we had to photograph the board and annotate the photos with the zones, temperatures, etc.
The sampler kit was something around $500, and it was composed of 75% consumables.
After adding up all the prep time, unknown amounts of replacement "paint", margin of error on thickness, and of course the occaisional need to replace a chip on a coated board, it ended up being cheaper to get a $10-15k thermal camera.
Nowadays, there are low res thermal cameras that snap onto a cell phone starting at a couple hundred bucks. The software has only gotten better over the years as well.

On Aug 27, 2017 8:05 AM, "'keith printy' keethpr@... [Homebrew_PCBs]" <Homebrew_PCBs@yahoogroups.com> wrote:
 

I used to have one. I remember 2 digits showing but if you knew how you could accurately read it.as I recall it was green when it was exactly that temperature and would turn more brownish below that temperature,above that temperature it was more bluish.by which numbers were lit you could figure out within about a degree what the temperature was.

 

Also had a replica of a galileo thermometer with the floating spheres inside, this wasn’t very accurate the lcd was much closer.

 

 

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@ yahoogroups.com]
Sent: Saturday, August 26, 2017 10:43 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: Chemical question

 

 

Probably a liquid crystal thermometer - they were sort of popular a few years ago, I haven't seen one in a while. From what I remember, their main problem was that they didn't jump discretely from one temperature reading to another - there were usually 2 different numbers showing at the same time.

 

 

Roy