The proliferation of increasingly stringent requirements for micropore density and signal integrity in printed circuit boards in the electronics industry reveals the reliability of micropore structures in high-performance products. Many IPC OEM member companies have provided IPC with examples of microporous failures in high-end hardware. These examples were not observed until the bare PCBA was manufactured, inspected and accepted, including:
On line test after reflow soldering
Environmental Stress Screening (ESS) during “box level” assembly
In service (final customer on-site products)
Many of these failures occur in products that have passed traditional production lot acceptance tests according to existing IPC-6010, PCB qualification and performance specifications. The data obtained by IPC indicate that the traditional detection technology that only uses thermal stress microsection and optical microscope is no longer an effective quality assurance tool to detect the fault from micropore to target coating.
Related to this, IPC released IPC-WP-023 in 2018, which is a white paper on IPC technology solutions. This white paper is a performance based OEM acceptance of printed circuit boards, entitled “Passing chain continuity reflow test: hidden reliability threat – weak microporous interface”. Asserting the reliability problem of stacked micro vias related to the weak interface between the target pad of the micro vias and the electrolytic copper filling, and providing data that supports the observations reported by many IPC OEM member companies.
Due to IPC-WP-023, IPC V-TSL-MVIA Weak Interface Micro via Fault Technical Solutions Subcommittee was established at the end of 2018 to investigate the potential causes of these faults and provide industry resources on this topic. The team provided the first update to the industry at the public forum held during IPC APEX EXPO 2019, and will continue to provide updates as the process progresses.
In this regard, IPC issued the following warning statement, which will also be included in the forthcoming IPC-6012E “Qualification and Performance Specification for Rigid Printed Boards”:
“In the past few years, there have been many examples of post fabrication microporous failures. Usually, these failures occur during reflow, but they are usually undetectable (potential) at room temperature. During assembly, the more obvious the failures are, the more expensive they become. If products are not found until they are put into use, they will pose a greater cost risk, and more importantly, may pose a safety risk.”
Looking forward to the future, IPC is working to get rid of the concept of traditional microsection evaluation and focus on performance-based acceptance testing, which was proposed by the IPC D-33a rigid printed board performance task group responsible for the IPC-6012 specification a few years ago. IPC, together with the Task Force, IPC 1-10c Test Coupons, Drawings and Generation Task Force and D-32 Thermal Stress Test Methods Subcommittee, continued to work on revising its existing thermal stress test methods (IPC-TM-650, Method 2.6.27) and thermal shock (IPC-TM-650, Method 2.6.7.2). These methods use performance-based acceptance test coupons that use resistance measurements, such as IPC-2221B Appendix “D” coupons.
About IPC
IPC is a global industry association located in Bannockburn, Illinois, dedicated to the competitive excellence and financial success of its 5000 member company sites, which represent all aspects of the electronics industry, including design, printed board manufacturing, electronic assembly and testing. As a member driven organization, and the main source of industry standards, training, market research and public policy advocacy, the plan supported by IPC can meet the global demand of the electronic industry estimated at $2 trillion. IPC has other offices in Taos, New Mexico; Washington DC; Atlanta, Georgia; Brussels, Belgium; Stockholm, Sweden; Moscow, Russia; Bangalore and New Delhi, India; Bangkok Thailand; Qingdao, Shanghai, Shenzhen, Chengdu, Suzhou and Beijing, China.