There are a variety of factors influencing the board level product quality. This paper mainly studies the soldering joint quality and the first pass yield from the components, printed board, design, technology, materials and other aspects. The test is divided into two parts, i.e. the deformation test and solder ball oxidation test in the first part as well as bonding pad design, assembly technology and material test in the second part. The test adopts nitrogen and the air to compare the probability of defects in the two atmospheric conditions and concludes that:The surface oxidation of the solder ball of the components affects the soldering quality. When the oxidation layer thickness reaches 250nm, the solderability is poor, resulting in soldering joint defects.The bonding pad design of the printed board will also affect the soldering quality. Good bonding pad design will lead to high first pass yield and poor design results in soldering joint defects such as HIP.The hot melting of soldering under air conditions is 3 times that of the basic hot melting Q and can fully guarantee the soldering joint quality. The soldering hot melting of the nitrogen reduced to 0.5Q can also guarantee good soldering first pass yield.

A diffusion bonding technology with an uniaxial pressure to the bonding region during the thermalcycle using a superconducting powder interlayer has been applied to join Bi-Sr-Ca-Cu-O 61 multifilamentary superconducting tapes. The precursor powders used for the preparation of Bi-Sr-Ca-Cu-O tapes were adopted as interlayers, which were mainly composed of Bi-2212 phases. The effects of holding time and uniaxial pressure on the superconductivity and microstructures of the joints were investigated preliminarily. The results indicate that appropriate holding time and uniaxial pressure during the diffusion bonding had beneficial effects both on the formation of metallurgical interface between the powder interlayer and superconducting cores and on the superconductivity of the joints. The Bi-2212 phases of the powder bonding interlayer partially decomposed into (Sr,Ca) 2 CuO 3 , CuO and other non-superconducting phases at bonding temperature during the several hours of holding time. The average superconducting critical current of the joints reached up to 38% of that of the original tapes.