Reliability of Clad Metal Inlays for Electrical Connectors

Following the prior publication [ 1 ], we tested more connector hardware of clad metal inlays the quality of which is quite close to the production level. In other words, the spring base material was all made of beryllium copper fully heat-treated after forming. The springs were punched and formed with a production the spring gaps were more uniform and all within the specified range, though in the high end. The inlay materials used in this extended test were: a) 18K Au (75Au25Ag), b) pure palladium (100 Pd), c) Alloy 69Au25Ag6Pt, d) 60Pd40Ag alloy, and e) alloy-55(55Au39Ag3Cd31n). These materials were reported to have relatively better performance among the many candidates we initially studied. The sample size used in these tests was much larger than the previous one; as a result, the experimental data are more reliable and meaningful. Two groups of connector hardware representing today's highdensity miniature electronic packaging were used. One group was the cylinder-cylinder contact, the other was the cylinder-flat contact. Also some discussion was devoted to the dimple-flat contact system. The contact-resistance data were collected over a period of 6 months to 1 year from three kinds of environmental tests. Both porosity and formability were acceptable for all the inlay springs. No wear-through contacts were found after 50 insertions with lubricant applied on the Au or Pd plated pins. All five inlay materials tested behaved almost equally well in their contact-resistance measurements. Previously the 69Au25Ag6Pt was chosen as the best, and the palladium stood as the second best at that time. However, in this paper we have shown that the Pd is clearly the winner in many aspects of the tests. The 69Au25Ag6Pt is equivalent to the 75Au25Ag alloy as the second best choice.