Issue link: https://iconnect007.uberflip.com/i/1518339
72 SMT007 MAGAZINE I APRIL 2024 test. It is possible to reduce the frequency of pull force testing if at the beginning of the pro- duction run, the conditions of the crimp tool and materials are verified, and the settings of the tool remain unchanged throughout the process. However, the project needs to eval- uate the impact to risk from reducing the fre- quency of testing prior to implementing pro- cess changes. Introduction is work presents a com- par ison of the pull test requirements of the NASA- STD-8739.4 Change 2 and the IPC/W HM A-A-620C s t a n d a r d 1 – 2 . It i s k n o w n that the pull force strength requirements in both stan- dards are similar, except for large gauges (i.e. 8 AWG wire size). However, in practice pull force strength test fail- ures occur at significantly higher values. In this paper we are presenting a statisti- cal analysis of the pull test records for past NASA proj- ects and the results of an investigation into recent crimp-related problem fail- ure reports documented at NASA Goddard Space Flight Center (GSFC). e percent- age difference between the pull force test values tabulated in the NA SA-STD -8739.4 Change 2, Table 12-1 Crimp Tensile Strength and the IPC/ WHMA-A-620C, Table 19-12 Pull Test Force Values were plotted for the machined contacts' silver/tin plated wires and nickel-plated wire as shown in Figure 1 and Fig- ure 2, respectively. Crimping is the process of deforming one contact member around the other to establish an electrical and mechanical joint between the members. Typically, one of the members is a wire and the other is a cylinder that is deformed around the wire. e reliability of the crimping process depends on the formation of an ade- quate metallic contact between the wire and the connector and the creation of a permanent crimped termination 3 . Figure 1: Percentage difference between the NASA-STD-8739.4 and IPC/WHMA-A-620C Silver/tin requirements for pull force testing. Figure 2: Percentage difference between the NASA-STD-8739.4 and IPC/WHMA-A-620C nickel plated requirements for pull force testing.