The proliferation of increasingly stringent microvia density and signal integrity requirements in printed circuit boards within the electronics industry has revealed the reliability issues of microvia structures in high performance products. Many IPC OEM member companies have brought to IPC examples of microvia failures in high-end hardware that were not observed until after the bare printed circuit board was fabricated, inspected, and accepted, including:
On-line test after reflow soldering
During "box-level" assembly, Environmental Stress Screening (ESS)
In service (end customer on-site product)
Many of these failures have occurred in products that have passed traditional production lot acceptance testing according to existing IPC-6010, Printed Circuit Board Qualification and Performance Specifications. IPC has obtained data showing that traditional inspection techniques using only thermal stress microsections and optical microscopy are no longer an effective quality assurance tool for detecting microvia-to-target coating failures.
On a related note, in 2018 IPC published IPC-WP-023, an IPC Technology Solutions white paper based on performance-based printed circuit board OEM acceptance, titled "Passing Chain Continuity Reflow Testing: Hidden Reliability" Sexual Threats - Weak Microporous Interfaces". Asserts stacked microvia reliability issues related to weak interfaces between microvia target pads and electrolytic copper fills, and provides data supporting observations reported by many IPC OEM member companies.
As a result of IPC-WP-023, the IPC V-TSL-MVIA Weak Interface Micro Via Failure Technical Solutions Subcommittee was established in late 2018 to begin investigating the potential causes of these failures and provide industry resources on the topic. The group provided the first update to the industry at an open forum held during IPC APEX EXPO 2019 and will continue to provide updates as it progresses.
In response, IPC has issued the following warning statement, which will also be included in the forthcoming IPC-6012E "Qualification and Performance Specification for Rigid Printed Boards":
“Over the past few years, there have been many examples of post-fab microvia failures. Typically, these failures occur during reflow, but are often undetectable (latently) at room temperature. During assembly, the more pronounced the failures, the more they become The more expensive they are. If they are not discovered until after the product is in use, they present a greater cost risk and, more importantly, a potential safety risk.”
Going forward, IPC is working to move away from the concept of traditional microsection evaluation and focus on performance-based acceptance testing, which was proposed several years ago by the IPC D-33a Rigid Printed Board Performance Task Group responsible for the IPC-6012 specification Suggest. . Together with this task group and the IPC 1-10c Test Coupon and Artwork and Generation Task Group and D-32 Thermal Stress Test Methods Subcommittee, IPC continues to work on revising its existing thermal stress test method (IPC-TM-650 , Method 2.6.27) and Thermal Shock (IPC-TM-650, Method 22.214.171.124). These methods use performance-based acceptance test coupons that use resistance measurements, such as IPC-2221B Appendix "D" coupons,
IPC is a global industry association based in Bannockburn, Illinois, dedicated to the competitive excellence and financial success of its 5,000 member company sites representing all aspects of the electronics industry, including design, printed board manufacturing, electronics assembly and test. As a member-driven organization and a primary source of industry standards, training, market research and public policy advocacy, IPC-supported programs meet the needs of the estimated $2 trillion global electronics industry. IPC has additional offices in Taos, New Mexico; Washington, D.C.; Atlanta, Georgia; Brussels, Belgium; Stockholm, Sweden; Moscow, Russia; Bangalore, India and New Delhi; Bangkok, Thailand; and Qingdao, Shanghai, Shenzhen, Chengdu, Suzhou, and China Beijing.