Method for uniformizing temperature field of current assisted sintered nano-silver soldering paste on basis of DBC (Direct Bonded Copper) ceramic substrate

Abstract

The invention relates to a method for uniformizing a temperature field of current assisted sintered nano-silver soldering paste on the basis of a DBC (Direct Bonded Copper) substrate. The shape of a copper layer of the DBC substrate and a region where an electrode pressure head after the nano-silver soldering paste is printed can be placed are combined; each special-shaped electrode is of a rightangle L shape; an interior angle of each special-shaped electrode is in transition of one fourth of an arc; before sintering, the electrodes are pre-pressed at both ends of the DBC substrate; appliedpulse direct currents uniformly flow the soldering paste; the sintering temperature field of the nano-silver soldering paste is uniformly distributed; and a chip is uniformly heated. According to theinvention, a problem of uneven temperature in process of rapidly sintering the nano-silver soldering paste by the currents is successfully solved; by designing the special-shaped electrodes applying the currents and position distribution, uniform distribution of the temperature field in the nano-silver soldering paste pulse current assisted sintering process and one-time rapid sintering connectionbetween a sintered nano-silver soldering paste IGBT chip/diode chip and the DBC ceramic substrate are implemented; obtained compactness reaches over 90%; mechanical intensity and anti-fatigue reliability of a sintering interconnection layer are greatly improved; and the service life is prolonged.

Description

technical field [0001] The invention relates to a method for assisting the temperature field of sintering nano-silver solder paste based on a uniform current of a copper-clad ceramic substrate, which belongs to the field of packaging of electronic components. Background technique [0002] DBC (Direct Bonded Copper) copper-clad ceramic substrate has excellent thermal conductivity, high insulation, high bonding strength, easy to print graphics, good solderability, etc., and has been widely used in power electronics such as GTR, IGBT, MCT, etc. module. In module manufacturing, the limited space of the DBC substrate is divided into three mutually insulated areas: the chip welding area, the electrode terminal welding area, and the bonding wire area. The chip bonding area occupies the main area of ​​the DBC, and enough space must be left for chip bonding in the design. [0003] Nano-silver solder paste has the advantages of high melting point (961°C), excellent electrical and th...

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Problems solved by technology

[0006] The present invention mainly solves the problem of uneven temperature distribution in the process of current-assisted rapid sintering nano-silver solder paste connecting IGBT chips and diode chips and DBC substrates, and the resulting low mechanical strength and poor fatigue resistance of the sintered joints. The study found that the shape of the electrode significantly affects the temperature distribution of the nano-silver solder paste during the current-assisted rapid sintering process. By designing the special-shaped electrode and position distribution of the applied current, the temperature field of the current-assisted sintered nano-silver solder paste is evenly distributed, and the overall mechanical strength of the sintered joint is improved. and fatigue reliability

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