Issue link: https://iconnect007.uberflip.com/i/1527952
34 PCB007 MAGAZINE I OCTOBER 2024 For enhanced DIG capability, we recently introduced a commercially available DIG thick gold, which has extended DIG applications to more complex assembly processes and made the process more compatible with wire bond- ing operations. We envision companies with new final finish lines incorporating this into their overall growth strategies, and using it as an important tool for "future-proofing" their operations. Is Uyemura currently using sputtering as an application process for any of your plating finishes? If so, please explain that process/ technology. Uyemura does not use sputtering (or vapor deposition) in any of its processes or applica- tions. e major reason is that Uyemura is pri- marily a specialty chemical solutions provider vs. a metals supplier. Uyemura's mission is to replace processes such as sputtering and vapor deposition with alternative metallization using chemical electrolytes such as plating baths. Given equal playing fields for performance, history shows that a chemical electrolyte is less expensive and more scalable in cost, efficiency, and productivity. e result is that although sputtering is commonplace, it has serious lim- itations in scalability, productivity, and long- term cost management. So, we continue to focus on substrate metallization using chemi- cal electrolytes. Related to chemical electrolyte metallization of substrates used in the PWB and microelec- tronics industries, we have primarily focused on electroless copper and specialty pretreat- ment chemicals that improve copper adhe- sion to organics, filled organics, organo-metal- lics, composites, and specialty glass substrates. e capability to thinly metallize a variety of substrates, including specialty glass, will help PWB manufacturers move to the next phase of high-density circuitry: HDI and IC substates. We are gratified that today's business climate is encouraging North American PCB investment, including IC substrates facility subsidies. What should PCB manufacturers be asking when considering moving to or adding direct metallization to their shops to replace traditional plating methods? e most logical strategy is to have an HDI/ UHDI strategy roadmap defining separate pro- cesses, pursuing evolutionary processes first for 25-micron lines and spaces, then moving to sub-15 micron line and space density. e limit of an modified semi-additive pro- cess (mSAP) based on subtractive PWB man- ufacturing is between 40 and 25 microns. By gaining experience and process knowledge using a subtractive mSAP process with thin laminated copper-clad substrates, you will be well positioned for evolution to a semi-addi- tive process (SAP) which uses an electroless copper-plated substrate process as the metal- lization step. e mSAP process flow is familiar to most PWB manufacturers and will require only a few "carefully placed process enhancements" to achieve prototype capability—and even pilot production. is experiential learning of first using mSAP will pay dividends for the phase 11 pro- cess evolution, which is required for a full SAP process. A full SAP requires plating a thin elec- troless copper deposit on an unclad substrate; this ultra-thin copper deposit seed layer allows finer lines and spaces with minimal circuit geometry undercut. A number of the "carefully placed process enhancements," as well as the evolution to a full SAP process, will require specialty etching " We continue to focus on substrate metallization using chemical electrolytes. "