Method for producing low-resistance conductive printing paste

Abstract

The invention relates to a method for producing low-resistance conductive printing paste. The following materials are adopted: 1# material, which is lead soldering paste with a melting point of 183 DEG C, comprises 63% of tin powder and 37% of lead powder, and has a granularity of 25-35 microns; 2# material, which is lead-free solder paste with a melting point of 227 DEG C, comprises 99% of tin powder, 0.3% of silver powder and 0.7% of copper powder, and has a granularity of 25-35 microns; and 3# material, which is lead paste with a melting point of 300 DEG C, comprises 95% of lead power and 5% of copper powder, and has a granularity of 25-35 microns. The production method comprises the following steps: taking 100 g of 1# material, 300 g of 3# material and 1.8 g of 2# material, making the width, length and thickness of to-be- produced paste be 0.6-1 mm, 5-20 mm, and 0.1-0.15 mm respectively, and heating the to-be- produced paste using a hot air reflow oven at the temperature of 250 DEG C to form the low-resistance conductive printing paste. The method has the advantages that the low-resistance conductive printing paste prepared by the method has a resistance of less than 2 mOmega / square meter, wide application prospect and good economic and social benefit, and is low in production cost.

Description

technical field [0001] The invention relates to a production method of low-resistance conductive printing paste. Background technique [0002] At present, the P10 monochrome screen is the most widely used type of LED display, commonly known as the door screen, the size of the P10 monochrome screen unit board is 16cm×32cm, each unit board has 512 light-emitting tubes, the power supply of the unit board The voltage is 5V, and the current is 1.5A-3.5A. Since the P10 unit board has 512 light-emitting tubes and 20 integrated circuits and other devices, there are many types of layout and wiring. The printed boards used by all manufacturers of P10 unit boards in the country are It is FR4 double-sided perforated printed board. If 94V0 single-sided paper board is used, the cost can be greatly reduced. [0003] However, after several rounds of optimization for single-panel wiring, there are still about 200 cross-lines, otherwise they cannot pass through. These 200-plus cross-lines mu...

AI Technical Summary

Problems solved by technology

[0006] The effect of the above improvement test is not ideal, and there are three failure results: 1. If the proportion of copper powder increases, the proportion of solder paste decreases, the temperature decreases, and the cross-line formation is very good, but the resistance is large; 2. If the proportion of copper powder decreases, When the proportion of solder paste increases, the temperature rises, and the cross-line will shrink and break; 3. If the proportion of copper powder and solder paste is appropriate, and the temperature is appropriate, the cross-line can be formed, and the resistance is about 5mΩ / □. This result seems to be barely feasible on the surface. , the resistance is slightly larger, but it is not true in fact, because the forming temperature requirement is too high, there can only be an error of ±1°C, and the hot air reflow furnace is used for heating and forming, and the temperature distribution error of the hot air reflow furnace is ±3°C, so high temperature point requirements will not really be enforced

[0007] There are several reasons for the failure of the analysis of the above three results: 1. The solder paste has a high surface tension after melting, and it will shrink into a round bun after fully melting; 2. The fluidity of the solder paste is good after melting; 3. The copper ratio The specific gravity of solder is light (copper does not melt, but it is easily pulled by the melted solder), and the simulated power-on test is carried out on the barely formed cross-line, and the hot air heating and natural cooling test is carried out on the printed board at the same time (10°C-100°C- 10°C-100°C...) 10 times a day, after a few days, some cross-section fractures occurred across the lines, and the reasons for the fracture were analyzed: first, the copper and solder paste were not fully combined, or the bonding strength was low; second, the heat of the 94V0 paper board Large expansion and contraction coefficient