Acid-washing process for diode chip

Abstract

The invention relates to a production process for diodes. The production process comprises five steps of acid washing, electroplating, welding, insulation protection and post-treatment. The production process for the diodes has the advantages that the steps of acid washing, welding and welding are performed in sequence; a chip is subjected to acid corrosion before welding, so that solders and metal impurities in lead wires are prevented from reacting with an acid liquid to influence a corrosive rate of the chip in the acid washing process; metal ions generated by reaction of metal and acid are prevented from being adhered to the surface of the chip, so that large amounts of washing processes are removed and resources are saved; the faults such as electric degradation and high-temperature thermal breakdown of a product are avoided, so that the electric yield of the product is increased; and meanwhile, the metal content of a discharged washing liquid is reduced and the soil pollution is alleviated, so that the environmental protection is facilitated.

Description

technical field [0001] The invention relates to the field of diodes, in particular to a pickling process for diode chips. Background technique [0002] According to the principle of diode semiconductor production, when the chip is to function, it must undergo acid corrosion and acid passivation. The pickling process of the diode chip includes one pickling, two pickling, mixed cleaning with ammonia water and hydrogen peroxide, and finally ultrasonic cleaning with water. [0003] At present, the cleaning solution in the primary pickling is a mixture of nitric acid, sulfuric acid, hydrofluoric acid and glacial acetic acid; there are two types of cleaning solutions in the secondary pickling: 1. A mixture of phosphoric acid, hydrogen peroxide and water. Disadvantages: there is Pb in the solder, During a pickling, it will react with sulfuric acid in the cleaning solution to form PbSO 4 , lead sulfate is an insoluble substance, it will be adsorbed on the surface of the chip, and t...

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Problems solved by technology

[0003] At present, the cleaning solution in the primary pickling is a mixture of nitric acid, sulfuric acid, hydrofluoric acid and glacial acetic acid; there are two types of cleaning solutions in the secondary pickling: 1. A mixture of phosphoric acid, hydrogen peroxide and water. Disadvantages: there is Pb in the solder, During a pickling, it will react with sulfuric acid in the cleaning solution to form PbSO 4 , lead sulfate is an insoluble substance, it will be adsorbed on the surface of the chip, and the pickling solution cannot remove the PbSO adsorbed on the surface of the chip 4 2. The mixture of phosphoric acid, hydrogen peroxide, water and glacial acetic acid, with a volume ratio of 1:0.8:3:0.2, can dissolve PbSO on the surface of the chip 4 , reduce the free metal ions on the surface of the chip, improve its electrical performance at room temperature and high temperature electrical performance, disadvantages: the residual glacial acetic acid contains high metal content, which will cause secondary pollution, thereby reducing electrical performance

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