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High demands on flexibility, lighter weight, thinner size and low-cost electronic product had increased the application of Flexible Printed Circuit Board (FPCB) over Rigid Printed Circuit Board (RPCB). However, the thermal factor affects FPCB significantly during the reflow soldering process. The temperature of the reflow soldering process causes the FPCB to encounter significant deflection and thermal stress compared to the RPCB. Therefore, the present experiment investigates the effect of temperature on FPCB layout during the reflow soldering process. The deformation of RPCB and FPCB was measured using a KEYENCE LK-G152 laser sensor placed at the entrance and outlet of the reflow oven. Two temperature profiles were used as a variable for the experiment: soaking temperature profile and ramp temperature profile. The investigation shows that component placements pattern influences the deformation of FPCB. The FPCB component placements reduce the deformation due to low wetting angle and component weight. FPCB solder joint has a good wetting angle (<90°), indicating good solder paste deposited on the FPCB. However, several solder joints on FPCB are irregular in shape due to high deformation. Therefore, it is essential to study the effect of temperature on FPCB during the reflow soldering process for industries guideline for mass production of FPCB products. [ABSTRACT FROM AUTHOR]

Flip chip technology is one of the common electronic packaging techniques used in the electronic industry. Before, the solder bump flip-chip bonding is used to provide the electrical connections and mechanical supports to the assembly. However, due to the fast-paced nature of technology, electronic packaging technique has become more challenging and complicated. The demand for smaller chip and interconnection joints causes the bottleneck of the conventional flip-chip technology. In order to fulfill the rising demand from the emerging market, a copper (Cu) pillar bump with a solder cap is proposed to replace the conventional solder bump. Due to the electrical and mechanical properties of Cu, it can improve the electrical performance of interconnection joint and provide mechanical support to the package. In this paper, ANSYS Fluent is used to develop the models of the conventional solder bump and Cu pillar bump. The thermal behaviour of interconnection joint during solder reflowing process is simulated. The simulation results indicate that the heat transfer of Cu pillar bumps in the reflow oven is better than conventional solder bumps. [ABSTRACT FROM AUTHOR]