Helping to develop a cutting edge polymer coating

Overview

Client profile –  Inventor of novel Low Vacuum Plasma processing to impart a hydrophobic film on virtually any substrate.

We were approached by our client to develop a multipurpose plasma deposited coating with the capability of being applied on an array of potential applications, especially pertinent to a host of applications in the electronics sector.

Description of the advance in science or technology that was being sought

We sought to utilise vacuum plasma etching equipment to plasma deposit fluoroalkanes, fluorinated hydrocarbons and analogues in a uniform controlled and repeatable fashion, and for the replacement of metallic surface finishes for electronics and printed circuit boards.
The ability to deposit a uniform coating has significant environmental benefits, by reducing the amount of heavy metal laden effluent produced, the subsequent treatment and waste disposal. As well as, a considerable reduction in cost compared to precious metals such as gold and silver, which are routinely used in the Electronics sector. The development creates a faster process and therefore lowers energy consumption. The potential ‘green’ credentials for such an advance would be significant.

List of the scientific or technological uncertainties faced

Working together we quickly identified the following key areas as being the primary focus points:
  • Was it technically possible to utilise the Vacuum Plasma Deposition equipment to impart the correct type of materials to give the properties/effects we wanted to achieve?
  • Physical Properties :  We had to determine through trial and error and subsequent testing, whether and how consistently and uniformly if possible, the required films would be deposited.
  • Chemical Properties : It was unknown whether the subsequent coatings produced would impart the substrates used with the kinds of useful properties for industrial applications or across the breadth of variants encountered in the electronics sector.

Description of work carried out in order to resolve the uncertainties

Samples were produced (by designing test coupons, having these manufactured and subsequently sent to machine manufacturers with specific instructions on how to clean and coat them) and subsequently coated under a variety of parameters in controlled experiments. We varied a number of parameters to investigate the effect of the coatings and the subsequent properties exhibited including, temperature at which the plasma was applied, frequencies used by the RF plasma generator to vary the free radical agents generated, time of coating to ascertain the effect of thickness variation, variation in precursors  and monomers, variations in types of pre clean materials and process  used prior to coating (some of this was done in house), and various other parameters which were base sample substrate specific.
Once produced the samples were subjected to rigorous testing e.g.:
  • corrosion testing,
  • solder through testing,
  • multiple passes through reflow evens
  • contact angle hydrophobicity
  • oleophobicity
  • abrasion resistance
  • adhesion to a variety of different substrates
We found consistent high contact angles which indicated good hydrophobicity but abrasion resistance was an issue on a variety of substrates. which instigated further research into pre clean options prior to coating. Furthermore when applied to fabrics (for non electronics applications), on light coloured fabrics we found an unacceptable yellow discolouration and on solid samples there was a variation of coating thickness and uniformity – requiring further research and testing.
This promising technology is still being explored by both us and our client as we discover new and varied potential commercial applications and opportunities for the chemical films we are seeing.
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