High-adhesiveness low-temperature conductive silver paste for solar HIT battery and preparation method thereof

Abstract

The invention relates to high-adhesiveness low-temperature conductive silver paste for a solar HIT battery and a preparation method of the high-adhesiveness low-temperature conductive silver paste. The silver paste is prepared from materials, by mass, 37%-40% of silver powder, 39%-43% of silver-coated copper powder, 6%-7.5% of resin, 0%-1.5% of diluent, 2%-3% of curing agent, 0.4%-0.6% of dispersing agent, 6%-7% of first indium alloy powder and 3%-5% of second indium alloy powder. The low-temperature conductive silver paste is reasonable in component selection and low in cost, can obtain the better adhesive force and tension on a silicon wafer, has better stability in severe environments such as high temperature, high humidity and the like, and can meet the requirements of a silk-screen grid of the solar HIT battery.

Description

technical field [0001] The invention relates to the field of conductive silver paste, in particular to a low-temperature conductive silver paste with strong adhesion for solar HIT cells and a preparation method thereof. Background technique [0002] Heterojunction HIT (Hereto-junction with Intrinsic Thin-layer) solar cells (also referred to as HJT, SHJ, SJT, etc.), usually use n-type crystalline silicon as the substrate and wide-bandgap amorphous silicon as the emitter. It has a double-sided symmetrical structure, two thin intrinsic amorphous silicon layers on both sides of the n-type silicon substrate, a layer of p-type amorphous silicon emitter layer on the front, and a layer of n-type amorphous silicon film on the back surface; A transparent conductive oxide film is deposited on the thin layer of crystalline silicon by sputtering, and finally a conductive grid is prepared. [0003] The traditional sputtering method to prepare conductive grids has disadvantages such as hi...

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Problems solved by technology

[0003] The traditional sputtering method to prepare conductive grids has disadvantages such as high cost, complicated process, and low efficiency. Since HIT batteries use a-si to form a PN junction, HIT batteries can be completed at a low temperature below 200 ° C, so the current HIT battery The conductive grid can be prepared by screen printing with silver paste. The specific method is to pour the silver paste into one end of the screen printing plate, apply a certain pressure on the silver paste on the screen printing plate with a scraper, and at the same time The other end of the printing plate moves at a constant speed, and the silver paste is squeezed by the scraper from the mesh of the crystalline silicon to form a conductive grid of a specific shape during the movement.

[0004] The conductivity, viscosity, printability, and tensile force of the silver paste directly affect whether the conductive grid of the HIT battery can be used normally. At present, the conductivity, viscosity, printability, and tensile force of the silver paste on the market are not very superior. It is well known that the conductivity is affected by the content of silver powder in the silver paste. If the content of silver powder is too small, good contact cannot be formed. If the content of silver powder is lower than the threshold value, it will not conduct electricity. If the content of silver powder is too high, it will be difficult to disperse and easy to agglomerate, reducing viscosity and printability, making it difficult to print. Specific shape, and because the HIT battery is completed at a low temperature below 200°C, there is no silver powder sintering process during the preparation of the silver paste, and the silver powder and the silver and the substrate are bonded by organic resin, and the silver powder pulling force is too small, generally less than 1N ( The traditional crystalline silicon battery paste is sintered at high temperature, and the silver powder and the silver and the base material are connected to each other by surface fusion, and the pulling force is large), and it is easy to tear when subjected to a pulling force greater than 1N

[0005] Therefore, the applicant submitted a patent application with the application number CN201811156329.1 to the State Intellectual Property Office on September 30, 2018, entitled "A Low-Temperature Conductive Silver Paste for Solar HIT Battery and Its Preparation Method". The silver paste of the technical solution has excellent properties such as conductivity, viscosity, printability, and tensile force, which can basically meet the production needs, but the disadvantage is that in order to ensure the conductivity, the silver powder content is large, the cost is high, and the adhesion needs to be improved. , the hardness is not very superior

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