Solid crystal solder paste replaces silver glue into the new favorite in the field of flip-chip

In the packaging process, flip chip puts higher demands on the chip and package manufacturers. First of all, due to the active layer of the chip facing down, in the process of chip preparation and packaging, if the process is improperly processed, it is easy to cause large stress damage, which requires chip splitting, sorting, crystal expansion, solid crystal, and total Crystal and other aspects are optimized to ensure a better product.

In the solid phase of the package, the flip-chip process is not ideal for the soldering effect of the chip and the substrate, and there are often problems such as non-melting tin, poor adhesion, and residual residue, and the appearance of the solid crystal solder paste may be solved. problem.

The solid crystal solder paste has high thermal conductivity, small resistance and fast heat transfer, which can meet the heat dissipation requirements of the LED chip , and has stable solid crystal quality and high welding mechanical strength, which can effectively ensure the reliability of the solid crystal. The thermal conductivity of the die-cast solder paste also ensures that the current or the wafer or product it is in contact with will have a higher current.

According to the reporter's understanding, some packaging companies that are currently doing flip-chip processing have used solder paste as a solid crystal material.

As for why the die-casting paste is more used in the flip-chip process, the technical director of the morning technology, Wang Benzhi, explained that the traditional dressing chip is connected to the substrate by wire bonding, the electrical side of the chip is facing up, and the electrical face of the flip chip is facing. Next, it is equivalent to flipping the traditional wafer. “Because the electrical surface is facing down, if silver paste is used, it will cause leakage, and the solid crystal solder paste material is insulated. After the solid crystal is melted, it will not be compatible with the pad, so there will be no short circuit.”

At present, the technology of solder paste used in the flip chip process as a solid crystal material has been relatively mature. Domestic manufacturers including Guoxing Optoelectronics, Ruifeng Optoelectronics and Zhaochi have begun to use solid crystal solder paste for packaging.

However, the selection of flip chip technology, especially solid crystal materials, should be cautious. Although many companies in the market have used solder paste to reflow soldering, I believe that due to the inconsistent production equipment and chip structure in the industry, For packaging companies, there is no real way to confirm the way to use flip-chip technology, and production yield needs to be improved.