Good Morning Everyone,

We are in the process building a new inner layer facility and are considering using Cupric Chloride etchant. Does anyone out their have any suggestion on the safest, cleanest way to control the process ? Any suggestions would be appreciated.

Recommend using CU OX-310 Sodium Chlorate solution in place of Chlorine gas for copper oxidizer .Also , Chemcut 907 regen system is an easy conversion for this process.

Mike Covel
HMSC

In a previous life I etched innerlayer cores with cupric chloride. We had a Chemcut regenerator which used a venturi to suck in the replenishment components.

We used 50% hydrogen peroxide as the oxidizer. Peroxide is safer than chlorine in that it is not a pressurized gas which can kill people if a pipe cracks. The liquid does require special handling. On one occasion we had an operator attempt to use an empty peroxide barrel to store spent etch in. The barrel had enough peroxide left in the bottom of it to blow the bottom out ot the drum and take off like a rocket. For years there was a big dent in the ductwork overhead as a reminder. After the plant got going we had peroxide delivered in bulk and used stainless steel distribution piping. The day-tank in the process center had redundant level controls to prevent spills.

Using peroxide has it's downside. Even at 50% strength it is half water. This effectively dilutes your etchant and limits the amount of copper you can maintain in solution. This hurts economy slightly and also will reduce your etch factor slightly.

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Hello Jack.

My name is Marty Grove, and I have been employed by Atotech USA, or more commonly known as Chemcut for about 18 or 19 years now.

The three most common regeneration methods of Cupric Chloride etchant is a) Chlorine, b) Hydrogen Proxide, and c) Sodium Chlorate. Each have their advantages and drawbacks, but from a safety standpoint I agree with Mike Covel (hello Mike, should you read this... ) that Sodium Chlorate would be the safest.

Should you desire any further information... feel free to e-mail me (with a mailing address) and I will arrange to have some information sent to you directly.

I have just recently joined this forum, and look forward to reading and discussing topics presented in this forum.

Marty Grove
Atotech USA
HYPERLINK mailto:mgrove@ix.netcom.com mgrove@ix.netcom.com

Jack,
There are two common choices. Chlorine Gas, or Hydrogen Peroxide. When properly controlled, neither are a problem. However, if there is a problem, and eventually there is...

1) Chlorine gas can leak into the area. This is a toxic gas, which can be deadly. You get a leak, you evacuate the building. Been there, done that.

2) Hydrogen Peroxide, if etchant gets syphoned back into the Peroxide container, the copper will cause the peroxide to break down. This will release heat, and create pressure. I have known of a barrel to blow up! Also, a slow peroxide leak is dangerous. Over time, the water in the peroxide evaporates, and the peroxide concentrates. Once during maintenance, an operator (wearing gloves) wiped up a peroxide spill with a paper towel. The towel smoked and burst into flames. The operator refused to work in the area again!

I would still choose the peroxide again, and also use it in the micro-etch also.

George Franck
My opinions are just that.

One trick we discovered helps the process. The Chemcut regenerator uses timers to alternate between oxydiser and acid wehenever the redox is below the setpoint. The timers open solenoids to allow the big venturi to suck in the components. We found that by adding a third solenoid which is normally open we could allow air to be sucked in whenever the two chemicals were not feeding.

The air helps complete the second etch reaction which is the conversion of cuprous back to cupric. This helps maintain consistent etch rate during heavy loading. My experience was with peroxide but I don't see why it shouldn't work equally well with either oxidiser.

Relevant to safety, other than the drum incident which I described before, safety was not a problem in the three years we used the system.

Eventually we switched to alkaline etch for more speed along with most of the industry. I understand they are going back to cupric, since fine line considerations now outweigh speed requirements.