The kinds of solder ball
Ordinary solder ball (the content of Sn from 2-100 [%] [%], melting temperature range of 182 ℃ ~ 316 ℃). Common products containing Ag solder ball (Ag content of 1.5 [%], 2 [%] or [%] 3, melting point temperature in 178 ℃ ~ 189 ℃). Low temperature solder ball (contain bismuth or indium, melting point temperature is 95 ℃ ~ 135 ℃). High temperature solder ball (melting point is 186 ℃ ~ 309 ℃); Fatigue resistance high purity solder ball (common product melting point is 178 ℃ and 183 ℃). Lead-free solder ball (components of the lead to less than 0.1 [%]).
VCM, CCM special black glue, solder paste (temperature points are: medium temperature, high temperature, low temperature; powder particles as the no. 3, 5) solid crystal flip chip solder paste class (powder particles are: 5, 6, 7)。
The application of tin ball
Application the application of tin ball has two kinds, one kind is to level 1 (FC) interconnection of chip installed directly to the occasion, tin ball after the wafer cut into chips directly engage in nude chip, chip in the FC - BGA encapsulation and packaging substrate electrical interconnection; Another type of application is the secondary interconnection welding, the application by special equipment will be tiny solder balls a grain by a grain into the packaging substrate, solder ball and substrate by heat connection plate joint. In IC assembly (BGA, CSP, etc.), the chip with the motherboard, when welding is accomplished through a reflow furnace heating.
Tin ball manufacturing process
The two widely used tin ball manufacturing process, namely the quantitative method of cutting and vacuum spray method. The former are applicable to large diameter welding ball, the latter is more suitable for small diameter welding ball, also can be used for large diameter welding ball. Requirements for electrical and physical properties of the solder balls are mainly in the coagulation of density, solidification point, thermal expansion coefficient, volume change rate, specific heat, thermal conductivity, electrical conductivity, resistivity, surface tension, tensile strength and elongation, resistance to fatigue life. In addition, the diameter of the solder ball tolerance, roundness, oxygen content also is regarded as the tin ball the key indicators of quality competition.
