wbreuer

Topic: Gold Vacuum Deposition for IR application

We have a polycarbonate piece that has 1500 Angstroms of gold vacuum deposited on to it.  We had 100 parts done last fall and all were good.  We just had another 100 parts done recently, and most of the parts have spots on them.  The exact process is as follows: 1) dry nitrogen blow off 2) plasma clean with ionized argon 3) base chromium layer applied 4) gold depostion 5) dialectric overcoat layer.

These parts were molded at the same time as the first 100 parts.  The only difference is that they have been sitting on the shelf for the past 9 months, completely sealed to prevent contamination.  Does anyone have any ideas?

Rbeard2180

Re: Gold Vacuum Deposition for IR application

 Are you runing a vacuum dep process with the gold? Have you ran a residule gas analyzer to make sure your vacumm pump is not contaminating the process during the gold dep part of your process? it is a thought,

Rbeard2180

Re: Gold Vacuum Deposition for IR application

Sorry about the part of my last response about vacuum, If you are not careful you can turn off your vacuum pumps while there is still a large vacuum in the chamber. If you have done this, the chamber will start pulling the oil out of your backing pump and contaminating the chamber. you will be able to see this if you have a RGA and someone who knows how to read the craking pattern. If you do not and want to be on the safe side you will need to heat the walls of your chamber and bring it to the lowest vacuum level possible and let it run there for about 24 hours and see if the vacuum level has leveled off at it's max. This is outgassing the chamber, basically you are cooking the contaminates out of your chamber. Do not send any type of gas into the chamber while doing this. you must get it as clean as possible. after you have done this you can try to run more parts and hopefully you should see the spots go away. Do not ever leave your dep chamber open to atmosphere any longer than needed as the outside air will also contaminate your process. I hope this helps, and I hope you do not think I was talking down to you. good luck. Oh I thought of one other thing check all of your seals and make sure you are able to get to the lowest possible vacuum for your pumps.

asalspammer

Re: Gold Vacuum Deposition for IR application

I am looking for a procedure that will enable me to know the concentration of Sodium Bicarbonate I have in my bath.



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