Issue link: https://iconnect007.uberflip.com/i/1185676
NOVEMBER 2019 I PCB007 MAGAZINE 73 testing. This article does not dwell on the mechanisms that are involved in IMC genera- tion, as the topic is far too complicated to be sidelined as an incidental. Ultimately, the SJR should demonstrate high forces accompanied by high ductility. The target is to simulate ac- celerated shock-related wear and tear. The results of cold ball pull (CBP) testing and ball shear (BS) testing will be discussed in this section of the article. In Table 1, the solder assembly conditions for this article are represented. Cold Ball Pull Testing As outlined in Figure 15, the pull force is applied in the z-axis at a speed of 5 mm/s. Because SJR testing is performed on attached solder balls, the test vehicle is a solder defined (SMD) ball grid array coupon (BGA). The forc- es that are associated with SJR are related to the contact area exposed by the solder resist openings (SROs). A fracture graded as 4 in Figure 16 is a bond failure with probable low pull strength and poor fracture characteristics. These are consid- ered catastrophic failure and would be inves- tigated further in the field. For SROs that are 380 μm in diameter, the expected pull strength Figure 15: ANOVA, the impact of the nickel type on pull strength for CNF Au. Figure 14: The impact of the gold type on the fracture mode for CNF Au. Figure 16: The impact of the nickel type on the fracture mode for CNF Au. Table 1: Solder conditions for the solder joint reliability testing.