AGS - Service Notes

Service Note No: 01
To: RIE/CVD maintenance techs
Subject: Aluminum Electrode Corrosion

Problem: It has been found that water cooled aluminum electrodes are deteriorating after exposure to the cooling water. After a period of about 18 months of use, the electrodes have usually corroded to the point at which the O-ring seals are no longer leak tight. This may occur over a longer period of time, but no method of estimating has been developed yet. Once the seals are damaged, the electrode assembly must be replaced.

Solution: The electrode set must be replaced. If aluminum is used, it must be replaced at regular intervals. An alternative to that is to switch to stainless steel parts.

WARNING: DO NOT DISASSEMBLE OLD ELECTRODES UNTIL A COMPLETE SET OF REPLACEMENTS IS AVAILABLE. SEALS THAT HAVE BEEN EXPOSED MAY NOT BE SERVICEABLE. IN THAT CASE, LEAVE UNITS ASSEMBLED.

No technique for resurfacing the electrode seals is available as the corrosion goes deep into the base metal under the O- ring groove. The only solution is to replace the electrodes periodically. One, more permanent, solution is to replace the aluminum parts with a 306 stainless steel versions. These 306SST parts will last virtually forever and only require periodic cleaning.

The price is the same for either material so there is no advantage other than from a materials consideration. We have found that 306SST is compatible with all processes and exhibits vastly superior vacuum pump down characteristics and, therefore, we recommend it in all applications.

A.G.Services can provide all types of replacement electrodes for Semi Group or IPE systems. For a price quotation for your unique System 1000 electrode requirements, contact A.G.Services.

Preventive maintenance: Preventive maintenance: Check base pressure weekly, Check leak rate monthly, Perform a major PM at least once per year.

Note: Special electrode surface coatings are available. Call for more information.

Expert Tips: You can test for seal failure by pumping down to high vacuum and observing the Ion Gauge reading while turning the coolant pressure on and off. If the seals are failing, you may see an increase in the pressure when the coolant is on and a slight decrease when turned off.

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