Electroless Copper on "Polyphenylene Oxide"

 

Question:

I need information on metallizing a number of different polymers including polyphenylene oxide (PPO). H.I.

Answer:

The metallizing of polymers and non-conductors in general is a well-developed technology. The proper process depends on the polymer and non-conductor and the use of the finished parts. Everything from printed circuit boards, auto trim, faucet sets and draw pulls are made of non-conductive materials. All of these parts are metallized to give them their final form and function.

Briefly, the process has three major steps. Probably the most critical step in the process is preparing the surface of the material to allow for good adhesion. Mechanical roughening and chemical etching can do this. Mechanical roughening can be performed using sodium bicarbonate or similar materials as a blast media. Acids are usually used for the chemical etching, with chromic acid being one of the more common materials. After this step, the surfaces must be sensitized using various types of solutions. This step in turn is followed by the deposit of electroless copper or nickel.

There are a number of good references available: A book, Metallizing of Plastics-"A Handbook of Theory and Practice, edited by R. Suchentrunk, goes into more detail about the various processes used. The book is available from Metal Finishing Publications.

PPO is one of the more difficult polymers/plastics to plate. An interesting paper, Metallization of Difficult-to-Plate Plastics, by J. J. Steppan & B. McClure, discusses this polymer as well as a few other difficult to plate materials. The paper was presented at Sur/Fin 98. The process uses plasma oxidation and mechanical pretreatment for surface preparation prior to metallizing.