Method for cleaning diode grains in encapsulation flow

Abstract

The invention discloses a method for cleaning diode grains in an encapsulation flow. The method comprises the following steps of: 1, welding the diode grains and a lead by using a tin soldering paste; 2, performing acid corrosion on the diode grains; 3, removing chemical components remained on the surface of the diode grains with deionized water; 4, wrapping an insulating glue on the edge of the diode grains and then roasting and curing; and 5, heating and melting an epoxy resin, and then wrapping the epoxy resin outside the lead and the diode grains to ensure that a product has necessary mechanical strength, wherein the deionized water is the deionized water with heat; and the environment heat obtained in the step 4 or the step 5 is transferred into the deionized water by the heat through an air source heat pump air conditioner. In the method, the heat in the production flow is fully utilized to clean the diode grains, so that the method has the advantages of good cleaning effect, environmental protection and low consumption.

Description

technical field [0001] The invention relates to a cleaning method used in the packaging process of diode crystal grains, belonging to the field of semiconductor packaging. Background technique [0002] The rectifier uses the unidirectional conductivity of the diode to rectify alternating current, so it is widely used in circuits that convert alternating current into direct current. Semiconductor diode production process: [0003] Due to the mechanical damage layer on the edge of the diode grain after slicing, the normal PN junction characteristics cannot be formed, which is manifested as an electrical short circuit. Therefore, the edge burr and damage layer (about 5-10 μm) must be removed by pickling to obtain Diode unidirectional conduction characteristics. Pickling uses mixed acid solutions such as hydrogen peroxide and hydrochloric acid, and it needs to be cleaned before each process can flow into the next process. [0004] The main problem existing in the existing pro...

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Problems solved by technology

[0004] The main problem existing in the existing process is that the foreign matter on the surface after pickling cannot be fully removed. The foreign matter on the surface is mainly contaminated with impurities such as Sn, Pb solder debris, traces of F, Cl, hydrocarbons, hydrofluoric acid, hydrochloric acid and other residues. Therefore, it is easy to form a leakage current

At the same time, there are traces of hydrochloric acid, phosphoric acid, hydrofluoric acid and other pickling solutions remaining on the surface of the diode crystal grains, which will cause impurity ions to adhere around the diode crystal grains and form leakage channels, especially acidic substances remaining on the chip surface. The enemy of the reverse characteristics of high-voltage devices is also an important reason for the large fluctuations in product yields in summer and winter in general diode manufacturers. To ensure the same temperature for cleaning, a large amount of energy needs to be invested, and the overall cost is unacceptable.

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