Weiner International Associates Executive/Innovator/Strategist/Keynote Speaker/Director: Boards & Advisory Boards/Author/IPC Hall of Fame/Member SMTA, PCEA, EIPC, PCBAA
UHDI and substrates: Forming clean microvias for subsequent metalization in build up circuitry to connect to a trace below is a challenge. Some recommend high frequency pulsed lasers to eliminate/minimize debris in the holes. Would a photo imageable build up film solve this challenge?
Mark Lau
7mo
IC substrate and SLP products we have many years experience ,maybe can give you a help in future,Gene
Geoffrey Leeds
7mo
Depends if the photoimagable material has some key processing properties - but the key property from a materials contribution perspective is low the Coefficent of Thermal Expansion (CTE) of said material. Assuming uniform, consistent, and well controlled Cu formation & homogenous material cure, the material expansion during reflow or operational life will contribute the most to the principle stress experienced by the structure. If you can lower the CTE of the material you reduce the resulting stresses on the base of the MV and increase the chances of success significantly while becoming somewhat fault (debris within the base of the MV) tolerant. I know photoimagble polymers are used in Waffer level Packaging but don’t know enough about their post processing steps and capabilities to understand its repercussions on costs drivers/acceptance/performance for the UHDI market. Not a bad idea to explore.
Joseph Fjelstad
7mo
McDermid had a photo imageable dielectric build up technology in early days off HDI, the problem was copper peel strength was never high enough to pass muster with the specs. Still a good idea worth another look with fresh eyes IMHO
Distinguished Innovator, SME, Chemical Engineer
7moPhotoresists can be thought of as a non-permanent version of a photodefined dielectric are utilized in-process during pattern plate to help some Cu-filled microvia processes. Consider laser vs no laser, I believe the weak interface is still possible until the Cu to Cu metallurgical control is understood and then perfected. Consider a single crystal copper. When more Cu is added by epitaxy, how does this compare to no epitaxy? Suppose the target pad is equiaxed, is small or large grain better and does the added Cu need to mimic the structure? What about columnar, or columnar/equiaxed mix? Is it okay to have a distinct Cu to Cu interface or not? What about low angle vs high angle boundary? Cu to Cu metallurgy is key then anything else is possible. Thoughts?