High Reliability Assembly Process of CLGA Packaged Devices
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Beijing Institute of Space Mechanics and Electricity,Beijing 100089

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TN605

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    Abstract:

    In order to ensure the reliability of CLGA(Ceramic Land Grid Array)packaged devices,in this paper,secondary process design of the CLGA packaged devices were investigated by using Pb90Sn10 solder ball,Pb90Sn10 and Pb80Sn20 solder column,and Be-Cu/Sn60Pb40 Micro-Coil Spring(MCS)and Sn63Pb37 eutectic solder paste to assemble the devices on the printed circuit board through reflow soldering process. Through combination of finite element analysis and test,a high reliability assembly process suitable for such devices was explored. The finite element simulation models were established for the three components to simulate the stress and strain level.Mechanical and thermal experiments of the printed board assemblies were carried out. The simulation found minimum stress and strain in the micro-coil spring, lower stress and strain in the solder column,and maximum stress and strain in the solder ball.The research showed that the experimental verification was consistent with simulation results.The attaching Micro-Coil Spring devices had the highest reliability,whilst the attaching solder column devices had lower reliability,and the attaching solder ball devices had the worst. There were no cracks in the attaching micro-coil spring devices after 500 thermal cycles and vibration test.But some cracks appeared in the attaching solder column devices and the attaching solder ball devices. Solder joint metallographic microsection and SEM energy spectrum microstructure analysis met the requirements of aerospace standard. The fracture failure positions of the attaching solder ball and the attaching solder column devices all appeared in the touching position between the solder ball,the solder column and the printed circuit board.The thickness of the intermetallic compounds(IMC)layer and energy spectrum composition at the crack were normal.

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History
  • Received:December 21,2021
  • Revised:January 28,2022
  • Adopted:February 10,2022
  • Online: December 23,2022
  • Published: December 30,2022