BGA socket is most important part in the final testing which selects the good or bad chip of BGA packages. When testing BGA-type packages using a BGA socket, the characteristic contact conditions and mechanisms of surface degradation in a low and stable contact are essential. However, the electrical contact between the pogo pin and the solder ball of the BGA-type package becomes unstable following repeated touchdown operations since particles from the package outline gradually accumulate on the crown tip of pogo pin. The contamination caused by these particles causes the contact resistance to increase. Accordingly, this study develops an experimental procedure for investigating the effect of the particle contamination on the magnitude and stability of the contact resistance. Initially, an experiment is performed to establish the contact resistance between a plated beryllium-copper (BeCu) pin at various number of touchdown. Subsequently, an experiment is conducted to investigate the accumulation of surface particles on the crown tip following multiple touchdowns of the pogo pin with the surface solder ball. The worn-out of crown tip following 6,830 and 36,580 touchdowns, respectively, is examined using a scanning electron microscope (SEM). The experimental results are then integrated to establish a suitable tradeoff between the contact resistance and the number of contacts for the time of socket clean.
Abstract-A functional microstrip circuit module for annular slot antenna is proposed. This module consists of an annular microstrip line component, two PIN diodes and a DC bias circuit. Reconfigurable circular polarizations can be simply controlled by this functional module. Axial ratio is adjustable by changing the clip angle of the notch made by the annular microstrip line component. Simulated and experimental results have shown good impedance bandwidth for return loss and antenna gains in circularly polarized states.
The use of organic semiconductor thin film of Alq3 to design parasitic capacitance coupling parasitic for a referenced circularly polarized microstrip patch antenna is demonstrated in this report. Results of the measurements lead to the conclusion that the Alq3 thin film capacitive coupling parasitic influences the circularly polarization significantly with little shift of operation frequency.
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