Solder tray local tin plating method on circuit board

Abstract

The invention discloses a method for local tinning to the bonding pad on a circuit substrate, which enables lead-free tin plasma to be brushed to the spot welding position bonding pad of the circuit substrate through a steel mesh; the circuit substrate brushed with the lead-free tin plasma passes through the five areas of a reflow soldering machine for operating parameters in sequence, to form liquid tin coating covered in the entire spot welding position bonding pad, and after the circuit substrate cools, solid tin coating is formed in the spot welding position bonding pad. The invention utilizes the steel mesh to brush the lead-free tin plasma to the bonding pad of a common substrate, and utilizes the reflow soldering machine and depends on the wetting property of soldering flux, and the diffusion and the self positioning effect of the tin plasma to accomplish the tinning process of the bonding pad, the tin coating meets the process requirements of the thickness and the smoothness, and provides good basic conditions for the subsequent spot welding working procedure, and the manufacturer does not require to purchase special substrates for the substrate supplier, therefore, the production efficiency can be greatly improved, the qualified rate of the product can be increased, and the production cost of the enterprise can be reduced.

Description

technical field [0001] The invention relates to a tinning processing method, in particular to a method for partially tinning pads on a circuit substrate, which is applied to the occasion of spot-welding enameled wires by plating lead-free pure tin on pads on the substrate. Background technique [0002] At present, the method of plating lead-free pure tin on the substrate pads to solder enameled wires is still using the traditional manual method, that is, manual chrome-iron soldering enameled wires. The specific operation process is: first break the enameled wires in the tin furnace, and then assemble them. The personnel use ferrochrome to heat the tin wire, and solder the enameled wire to the pad by adding tin to the pad, so as to complete the assembly process of welding the enameled wire to the pad of the substrate. This manual welding method has the following disadvantages: 1. The traditional process It is necessary to operate the enameled wire breaking paint and pad tinni...

AI Technical Summary

Problems solved by technology

[0002] At present, the method of plating lead-free pure tin on the substrate pads to solder enameled wires is still using the traditional manual method, that is, manual chrome-iron soldering enameled wires. The specific operation process is: first break the enameled wires in the tin furnace, and then assemble them. The personnel use ferrochrome to heat the tin wire, and solder the enameled wire to the pad by adding tin to the pad, so as to complete the assembly process of welding the enameled wire to the pad of the substrate. This manual welding method has the following disadvantages: 1. The traditional process It is necessary to operate the enameled wire breaking paint and pad tinning procedures separately, and the production steps are cumbersome, resulting in low production efficiency. Since the entire welding assembly process is manually operated, human factors such as the operator's welding proficiency will greatly affect production efficiency; 2 , The professionalism of the operator is directly related to the reliability of welding. Operators with higher proficiency in welding operations have higher welding quality, such as uniform tin plating thickness, tin on the pad can completely wrap the enameled wire, etc. On the contrary, the welding lower quality

However, increasing the thickness of tin plating is a very special requirement for the substrate processing industry after all, and it is very difficult for substrate suppliers to realize this process, resulting in prolonged processing cycles and increased processing costs for substrates, and tin plating often occurs on the substrates produced. Non-standard phenomena such as uneven thickness and thin coating, when using this kind of substrate for spot welding, the welding reliability is poor, and the tin on the spot welding pad cannot completely wrap the enameled wire, resulting in a production defect rate of up to 10%.

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