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112 PCB007 MAGAZINE I SEPTEMBER 2020 Edited by Happy Holden I-CONNECT007 At the virtual IPC High-Re- liability Forum, Gerry Parti- da, field application engineer- ing manager at Summit Inter- connect, covered concerns re- garding the reliability testing of microvias in his presenta- tion titled "Current Concerns Over Microvia Failures." He also provided an overview of HDI process- es and discussed current test methods. Here, I share Gerry's presentation transcript, which has been slightly edited for clarity. Current Concerns Over Microvia Failures I'm going to share the knowledge that our team has accumulated over 20 years of making microvias, as well as information on what can be done to test your microvias for acceptance as it applies to today's IPC standards. Have you ever had to hold your finger down on a com- ponent to make it work, and when you let up, it stopped working (Figure 1)? It might be the reason why you are here today. Figure 2 shows a quote from an IPC news re- lease warning about microvia reliability. The industry has experienced failures of mi- crovias after the boards have been complet- ed and shipped to the customer, either at as- sembly or during thermal testing of a finished product. Customers have experienced failures that occurred even later. There is a way to check your microvia and ensure that you have a good microvia that will meet the assembly reflow process, as well as when doing ther- mal shock. Why do we test and then look? We don't see a lot of commercial companies; we see a lot of high reliability. The military-aerospace sector is more interested in this than U.S. commer- cial companies, and there is a reason for that. When they build a lot of these space products, they can only put the component down one time. It cannot be reused. If it's a custom ASIC chip with 1,400 I/Os on a BGA, or an ASIC Gerry Partida Emphasizes Current Concerns Over Microvia Failures Figure 1: A finger pressing down on a component to make it work. Figure 2: IPC microvia reliability warning press release. "There have been many examples of post-fabri- cation microvia failures over the last several years. Typically, these failures occur during reflow; however, they are often undetectable (latent) at room temperature. The further along the assembly process that the failures mani- fest themselves, the more expensive they become. If they remain undetected until after the product is placed into service, they become a much greater cost risk and, more importantly, may pose a safety risk." Gerry Partida

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