Electronic packaging-used tin-copper high-temperature lead-free pre-formed solder with copper core structure

Abstract

The invention relates to tin-copper high-temperature lead-free pre-formed solder with a copper core structure as well as a preparation method and application thereof, and belongs to the technical field of high-temperature soft solder. The solder comprises a purple copper foil sheet, wherein an upper tin-plated layer and a lower tin-plated layer are arranged on the upper surface and the lower surface of the purple copper foil sheet respectively; or the solder comprises a purple copper foil sheet, the upper tin-plated layer and the lower tin-plated layer are arranged on the upper surface and thelower surface of the purple copper foil sheet respectively, and an upper soldering flux layer and a lower soldering flux layer are arranged on the outer surface of the upper tin-plated layer and theouter surface of the lower tin-plated layer respectively. The tin-copper pre-formed solder with the copper core structure has the shape diversity same as a common pre-formed soldering piece, meanwhile, the ultra-thin, ultra-precision pre-formed solder structure meeting the application requirement of high-precision packaging can be prepared, the solder is suitable for the miniaturized personalizedrequirements of electronic elements, and except that the advantage of small-tolerance precise usage is realized, soldering flux is pre-coated to simplify the soldering process to reduce the splashingof the soldering flux; the electricity conducting and heat conduction performance of an assembly is improved while the bonding strength is ensured, the hardness of a soldered part is reduced, the brittleness of the soldered part is reduced, and the application of the high-performance high-temperature lead-free solder is realized in a true sense.

Description

technical field [0001] The invention relates to a tin-copper preformed solder with a copper core structure, in particular to a tin-copper high-temperature lead-free preformed solder with a copper core structure for electronic packaging, and the preparation method and application of the solder, belonging to the high-temperature solder technology field. Background technique [0002] Solder is a metal alloy material that fills the weld during welding. Solder bars, solder wires, solder balls, solder paste, etc. have been widely used in the PCB manufacturing process. However, with the development of electronic assembly technology, electronic components are becoming more and more With the development of miniaturization and individualization, and the development of electronics towards ultra-high power and ultra-high integration, the requirements for soldering materials are becoming more and more special. The existing solder bars, solder wires, solder balls, solder paste, etc. canno...

AI Technical Summary

Problems solved by technology

Chinese patent CN202240181U discloses a three-layer metal composite soldering sheet. This utility model is composed of three-layer metal structure. Tin alloy sheet, the three-layer metal sheet is welded together. This composite solder sheet is mainly used to replace the crimping connection method used by the microelectronic components of the semiconductor chip and the lead end, but because the upper and lower layers are silver-copper-tin alloy, it greatly inhibits Diffusion of elements during the welding process leads to a limited thickness of the diffusion layer, and the use of silver sheets as the main material leads to high costs and limits its application

Chinese patent CN105252173A discloses a method for preparing solder preforms with a uniform coating. The invention ensures that the upper and lower surfaces of the solder preforms are coated with flux by means of dip coating, and at the same time removes excess flux with a scraper to ensure coating The uniformity of the coating layer, and then the pressure wheel controlled by the air pressure controls the thickness of the coating to reach the required thickness, and at the same time eliminates the air bubbles inside the flux during the dip coating process, thereby ensuring the adhesion of the solder pad coating, and long-term storage coating The layer does not fall off, the process is complicated

Chinese patent CN103817062A discloses a coating method for coated solder preforms. In this invention, the flux prepared according to the requirements without adding solvent is poured into the spraying machine and the appropriate temperature is ensured. The upper and lower surfaces of the foil are coated at the same time. During the coating process, the coating thickness is adjusted by the speed of the liquid pump, the travel speed of the foil and the thickness of the gasket. Solder tabs have good soldering effect and precise dosage, but it is difficult to control the accuracy of equipment. The above two patents only involve how to optimize the process or equipment to make the pre-coated flux more uniform

At the same time, the IMC layer is a ceramic phase intermetallic compound, which has poor electrical and thermal conductivity and high brittleness. Too thick an IMC layer will seriously deteriorate the electrical conductivity, thermal conductivity and bonding reliability of the packaged component module.

[0006] The above is the situation of the related solder preforms, and there are also solder preforms in the form of solder balls (or solder columns). For example, Chinese patent CN 104538380 A discloses an ellipsoid, rectangular column or cylinder with solder plated on the surface of a copper core. Shaped Solder Preforms, However Diffusion Barrier Issues Still Exist

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