Improving the reliability of radar T/R module with precise cleaning technology
Because we adopt high precision microelectronic assembly technologies during the manufacturing of radar T/R modules, these modules are complex and delicate. Common cleaning technologies such as ultrasonic cleaning can't satisfy the requirement of high precision cleaning of these modules. This article introduces some precise cleaning technologies, these cleaning technologies not only can make T/R module achieve a high cleanness, but also does little harm to them, and they will greatly improve the reliability of T/R module.
A new bumping process using lead-free solder paste
In this paper, we report development of a new process for lead-free solder bumping with no flux residues, using stencil printing and hydrogen radicals, which can lessen both the environmental load and the manufacturing cost of solder bumping. In this process the reduction of the hydrogen radicals, instead of the flux, will eliminate the surface oxides of the stencil printed lead-free solder paste. Sn-3.0Ag-0.5Cu lead-free solder paste, which contains no residue flux was printed on an 8-in wafer. Hydrogen plasma was radiated for a minute during the reflow process, and the printed paste formed a bump. Reflow experiments without hydrogen radicals treatment were also carried out for comparison, where no successful reflow could be observed.
Hydrogen plasmas for flux free flip‐chip solder bonding
Flip‐chip solder bonding is a suitable technology for applications involving large numbers of interconnections. This technique, also known as controlled collapse solder bonding, was developed several years ago [L. F. Miller, IBM J. Res. Develop. 239 (1969)]. To facilitate reflow and bonding of flip‐chip devices using Pb–Sn solder, a method of removing the surface oxides on the molten solder is required. Conventional liquid fluxes are not desirable due to potentially corrosive residues that may be difficult to remove from the confined geometry between flip‐chip and substrate. Dry processing previously reported [P. A. Moskowitz, H. L. Yeh, and S. K. Ray, J. Vac. Sci. Technol. A 4, 838 (1986)] involves the use of halogen containing gases such as CF2Cl2, CF4 , and SF6 . However, halide residues on the surfaces of treated samples can corrode the solder surface and any other exposed metal when exposed to atmospheric moisture. This paper describes dry reflow and bonding of flip chips using Pb–Sn solder with atom...