Issue link: https://iconnect007.uberflip.com/i/1143487
JULY 2019 I PCB007 MAGAZINE 31 as press-fit pins and optical modules. The use of particle counters is getting popular in partic- ulate control on the manufacturing floor along with connector vacuuming, cleaning, and re- seating/inserting an edge card. Again, in most cases, these contact problems may not be per- manent but can be quickly resolved by double insertion of the interconnect system to provide a clean contact interconnect interface. Approach In this study, a realistic test vehicle (Figure 4) is designed with a commercially available press-fit connector of various sources on to a motherboard with full electrical function. A riser card is plugged into the press-fit connec- tor that serves as an interface for NIC and SSL card interconnect. The following three design variables were experimented on in addition to the pallet of test vehicles with an installed shock measurement device were shipped through two shipping routes as train and sea cargo to see the correlation to the function fail- ure of the test vehicle: • Damping plate for NIC and SSL cards • Hard gold plating thickness • Locking mechanism for motherboard Results and Discussion Design Variable Change Several design variables to improve the press-fit interconnect quality are considered to be tested in the shipping routes and during material handling. Some design changes were made specifically to solve the NIC/SSL poor contact issue. First, the plating thickness in various press-fit connectors on the test vehicle is measured. As shown in Tables 3 and 4, the gold (Au) plating thickness on some connectors is in the 1-mi- croinch range, and on the other, is more than Figure 3: Close-up view of particles on DIMM contact pads. Figure 4: Test vehicle with press-fit connector and riser card interface for NIC and SSL interconnect. Table 2: Chemical analysis of foreign material on contact pads.