Solder ball is one of the main technical ways in the modern three laser soldering process, together with laser wire and solder paste for the important processing process in the field of medium and tiny electronics. Shenzhen Zichen laser as the first domestic enterprises engaged in the research and development of laser soldering applications, has been committed to laser wire, solder paste and solder ball welding technology breakthroughs and industrialized applications. The core products have the characteristics of "high welding accuracy, high performance, non-contact, green and pollution-free" and so on. The following laser solder ball process, to understand how the solder ball is made? And the application and characteristics of solder balls.
01. How the solder ball is made
Tin balls are made from tin tetrachloride, which is purified by distillation, hydrolyzed to tin hydroxide, and then reduced by passing hydrogen gas to obtain high purity tin products. It is mainly used as compound semiconductor doping elements, high-purity alloys, superconducting solder, etc. Two manufacturing processes are commonly used, namely, the quantitative cutting method and the vacuum spray method. The former is more suitable for larger diameter solder balls, the latter is more suitable for small diameter solder balls, but also can be used for larger diameter solder balls. The physical and electrical properties of tin balls are mainly required for density, curing point, coefficient of thermal expansion, volume change rate during solidification, specific heat, thermal conductivity, electrical conductivity, resistivity, surface tension, tensile strength, fatigue life and elongation. In addition to these, the diameter tolerance, true roundness, and oxygen content of tin balls are also seen as key indicators of the current competition in the quality level of tin balls.
02. Types of Tin Balls
Ordinary solder balls (Sn content from 2 [%]-100 [%], melting point temperature range of 182 ℃ ~ 316 ℃); Ag-containing solder balls (common products containing 1.5 [%], 2 [%] or 3 [%] Ag, melting point temperature at 178 ℃ ~ 189 ℃); low temperature solder balls (containing bismuth or indium class, melting point temperature of 95 ℃ ~ 135 ℃); high temperature solder balls (melting point of 186℃～309℃).
03. Application of laser solder balls
From the aspect of material saving: in the traditional soldering process mostly use the soldering iron tip to provide the required energy, but with the BGA solder ball is used to replace the pins in the IC component package structure, so as to meet the electrical interconnection as well as mechanical connection requirements of a connection. Its process technology is widely used in digital, intelligent communication electronics, satellite positioning systems and other consumer electronics.
There are two types of tin ball applications, one application is the first level of interconnection of the inverted chip (FC) directly mounted to the occasion used, tin ball in the wafer cut into the chip directly bonded to the bare chip, in the FC-BGA package to play a chip and package substrate electrical interconnection; the other application is the second level of interconnection soldering, the application through special equipment will be tiny tin ball grain by grain implanted into the package substrate, by heating tin ball and the substrate on the role of electrical interconnection. By heating the solder balls, they are bonded to the connection plate on the substrate. In IC packaging (BGA, CSP, etc.), the chip is soldered to the motherboard by heating in a reflow oven.
The development of BGA/CSP packages follows the trend of technology development and meets the requirements of short, small, light and thin electronic products This is a high-density surface assembly packaging technology, which has very high requirements for bga rework table, bga packaging, bga rework and BGA ball implantation. High quality BGA ball must have true roundness, brightness, good conductivity and mechanical linkage performance, ball diameter tolerance, low oxygen content, etc., and precision, advanced ball production equipment, is the key to determine the provision of quality ball products.
04. Product Features
Laser ball implantation welding machine adopts fiber laser, highly integrated with industrial control system in the workbench cabinet, with ball implantation mechanism to achieve synchronization of tin ball and laser welding, with dual-station interactive feeding system, loading, unloading, automatic positioning, welding synchronization, to achieve efficient automatic welding, greatly improving the production efficiency, to meet the precision level components such as bga chips, wafers, communication devices, camera ccm modules, VCM enameled coil modules and contact baskets, etc. with the following application features:
- Solder balls with a minimum diameter of 60um with image positioning system; fast heating and melt-drop process, which can be completed within 0.3S;
- Applicable to a wide range of solder balls, SnPb (lead-tin), SnAgCu (tin-silver-copper), AuSn (gold-tin alloy), etc. Can support single piece loading or array loading;
- Linear motor marble integrated platform with precision up to 1um;
- Flux-free, non-polluting, non-spattering, maximum electronic device life;
- Can be extended with spray ball solder monitoring, and post-solder inspection function.
