Reliability Testing Of PWB Plated Through Holes Using Interconnect Stress Testing Thermal Cycling Before And After Pb-Free Reflow Preconditioning
Author: Bill Birch Company: PWB Interconnect Solutions Date Published: 10/13/2013
Abstract: The High Density Packaging Users Group Consortium completed their 3rd phase investigation into plated through hole reliability of printed wiring board test vehicles constructed with 24 different Pb-free capable printed wiring board materials. The study contained a total of 24 different constructions built by a single high-end Asia based PWB manufacturer. The materials were tested using Interconnect Stress Testing (IST) methodology. The test vehicle combined both via reliability and materials analysis testing capabilities, using two specially designed IST coupons with via to via spacing of both 0.040” (1mm) and 0.032” (0.8mm), All products were constructed with 20 layers, laminated to an average thickness of 0.115” (2.92mm), and drilled with 0.010” (0.254mm) vias, producing an aspect ratio of 11.5 to 1. Twelve materials were investigated with two different glass styles and resin contents. The materials were IST tested on the two coupon types, both as built and after 6X Pb-free (260°C) reflow. Materials in the test included four high Tg, filled FR4 materials, twelve high Tg halogen-free FR4 materials, and eight high speed materials. In addition, some materials were submitted into testing with the prior knowledge that material damage was present following the 6 cycles of assembly. Failure analysis was completed after IST thermal cycling testing and compared to the materials relative performance.