A kind of low-temperature flux and preparation method thereof

Abstract

The invention provides a low-temperature soldering flux and a preparation method thereof, which relate to the technical field of soldering. The low-temperature flux provided by the present invention is formed by uniformly mixing two low-temperature flux components; wherein, one of the low-temperature flux components is composed of low-melting-point metal microcapsules, polyvinylpyrrolidone, graphene and a solvent; The core material of the melting-point metal microcapsule is a low-melting-point metal whose melting point is lower than that of the pad; another low-temperature flux component consists of metal salt, activator, surfactant, defoamer and solvent. The technical scheme of the invention can reliably weld the electronic components and the low-melting-point metal circuit at low temperature.

Description

technical field [0001] The invention relates to the field of soldering technology, in particular to a low-temperature soldering flux. Background technique [0002] With the rapid development of low-melting-point metal electronic circuit printing technology, it has become a reality to use room-temperature liquid low-melting-point metals (usually below 200°C) to make circuit boards, especially flexible circuit boards. Flexible circuit boards based on low-melting-point metals include flexible substrates, low-melting-point metal circuits and electronic components formed on the flexible substrates, such as LEDs, membrane switches, touch switches, resistors, capacitors, sensors, and the like. Wherein, the low-melting-point metal circuit is connected with pads, and the electronic components are welded on the pads. [0003] The inventors have found that the following problems exist in the process of soldering electronic components: the pins of existing electronic components are coa...

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Problems solved by technology

[0003] The inventors have found that the following problems exist in the process of soldering electronic components: the pins of existing electronic components are coated with a tin layer, and the tin layer is easily oxidized to form an oxide film, and the melting point of the oxide film is higher than 200°C. Reliable soldering of electronic components and low-melting-point metal circuits requires melting the oxide film, but the existing flexible substrates are generally polymer materials, such as polyethylene (PE) film, polyethylene terephthalate (PET ) film, polyvinyl chloride (PVC) film, etc., the temperature they can withstand generally does not exceed 120°C. Exceeding their tolerance temperature will cause the flexible substrate to soften, deform or even form droplets, resulting in damage to the flexible circuit board.

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