Electroless copper plating and surface characterization of thermoplastic PPO based printed circuit boards

Teija Laine-Ma, Pekka Ruuskanen, Satu Kortet, Mikko Karttunen

    Research output: Contribution to journalArticleScientificpeer-review

    8 Citations (Scopus)


    Purpose – The adhesion between electroless copper and a substrate is one of the most important factors in the reliability of thermoplastic printed circuit boards. The purpose of this paper is to investigate the effects of mechanical grinding and acid etching of thermoplastic substrate materials on the adhesion of copper deposited by an electroless copper plating process. The base material of the test substrates was a new high temperature thermoplastic polyphenylene oxide (PPO) compound.

    Design/methodology/approach – The effects of pre‐treatment on plastic surfaces are analyzed by the following methods: Fourier transform infrared (FTIR), SEM, the Dyne surface energy test and the surface roughness test. The adhesion between electroless copper and thermoplastic substrate is measured with a peel strength test.

    Findings – The results showed that mechanical grinding of the substrates significantly increased adhesion but the highest adhesion is gained by using an acid etch treatment before electroless plating. These results indicated that adhesion between copper and the substrates was not directly proportional to the roughness and surface energy values.

    Originality/value – The conventional sweller/desmear treatment used in a printed circuit board factory for pre‐treating epoxy based laminates prior to electroless plating is not suitable for these PPO compound boards. The copper adhesion is adequate when the substrates are etched with sulphuric acid/chromate solution. In that case the bonding between the metal layer and the plastic surface is stronger than the bondings between the polymer chains of the thermoplastic material. The adhesion mechanism of electroless copper in these mechanically abraded samples is mechanical interlocking of metal particles.
    Original languageEnglish
    Pages (from-to)22-30
    Number of pages9
    JournalCircuit World
    Issue number4
    Publication statusPublished - 2009
    MoE publication typeA1 Journal article-refereed


    • electroplating
    • copper
    • adhesion
    • printed circuits
    • plastics
    • surface treatment


    Dive into the research topics of 'Electroless copper plating and surface characterization of thermoplastic PPO based printed circuit boards'. Together they form a unique fingerprint.

    Cite this