Issue link: https://iconnect007.uberflip.com/i/1002143
JULY 2018 I PCB007 MAGAZINE 19 Tibbals: Absolutely. We're basically pushing against an open door with this technology but customers need to be satisfied with the func- tionality and reliability and be sure that it's ready before they invest. This will be the first step change in solder mask technology in over 30 years. The last step change in technology was when we went from two-pack epoxy to photo - imageable. You could argue that we've been through significant iterations of photoimage- able. Originally, we were solvent developing and we went from solvent developing to aqueous de- veloping, and then we went from convention- al imaging to direct imaging. However, in many ways these are all variations of the same theme. They're different flavors of ice cream. Whereas now, by going to inkjet, it's a completely differ - ent change in approach and methodology. With that comes some reservation. Obvious- ly, the material has to meet all of the required standards and it must be fully accepted and ap- proved by the end user. The PCB manufactur- er must then invest in the capital equipment. Matties: Sounds like a few bridges need to be built. Tibbals: Exactly, but the drivers for change are there. I think over the coming years we'll see this process being gradually rolled out. Like anything, it will reach a point of critical mass, it will be accepted as mainstream and people will move quickly. Goldman: One interesting benefit of inkjet is that you don't have to put down as much be- cause there are many areas of a board that re- ally don't need solder mask on them, that get solder mask put on them because they get blanket-covered and it's left on. That's part of the education of OEMs and those that do the specifying—there may be big areas that don't need anything at all. There could be a huge savings in material and time. Earl: You're right there. The application of the photoimageable solder masks does put the sol- der mask all over the surface. With the inkjet and the data handling of that process, you can apply different thicknesses of material in dif- ferent areas of the panel. So, you could be put- ting the solder mask thicker in critical areas, and thinner in non-critical areas, such as over laminate areas, etc. Goldman: Or not at all, right? Earl: Or not at all. We would hate to see that happen, for obvious reasons [laughs], but that's going to be one of the acceptance criteria of inkjet solder mask: the appearance. It is go - ing to be different cosmetically to the eye, how it looks on the panel and how the panel ap- pears under magnification. Everybody is used to very straight lines and straight features now, from photoimageable and direct image solder masks, and inkjet solder mask is going to look a little different. Tibbals: I think it comes back to this accep- tance. Again, you've got this difference: The PCB manufacturer who may see the benefits and would want to move, but we also need to get the end user buy-in as well, because as Antony said, it will look different. Both to the eye and particularly under magnification, it will look very different. Doesn't mean it won't fit the purpose; it just looks different and it deals with things in a different way. Ultimately, you'll probably find that people will stop putting solder mask on certain areas of the board. And there could be huge material reductions from that perspective, and as such significant cost and environmental savings. I think that could be the driver to catch the larg- er OEMs' eyes. From a capital investment per- spective, not putting ink down where it isn't needed could possibly double output from an inkjet machine which may make justification and return on investment faster. It's just with any new technology, it's got to find its feet and people will start to exploit it to the maximum benefit possible. Goldman: Is dry film solder mask gone? Do some people still use it? Tibbals: I think there are still a few people who