Selective welding carrier and welding method thereof

Abstract

The invention discloses a selective welding carrier and a welding method thereof. The welding method comprises the following steps: adjusting a state and a welding parameter of a selective welding machine, and placing a welded plate into the selective welding machine; spraying a soldering flux; entering a preheating zone to preheat the bottom of the welded plate; entering a welding zone, and starting a hot air preheating device on the top of the welded plate to perform hot air preheating; meanwhile, preheating tin penetration difficult points; starting welding after preheating is finished; moving a welding spray head among welding spots at a uniform speed, reaching the welding spots in sequence, and performing welding; performing welding quality inspection, and returning to the step 1 to readjust the welding parameter if the welding quality is unqualified; and performing batch production if the welding quality is qualified. Through adoption of the method, 100 percent tin penetration can be reached effectively; a judgment standard is simple and clear; an industrial standard is exceeded; the welding spot reliability is enhanced; and the quality is ensured.

Description

technical field [0001] The invention relates to welding technology, in particular to a selective welding carrier and a welding method thereof. Background technique [0002] Existing selective soldering techniques include wave soldering or manual soldering. The disadvantage of wave soldering is that there is interference from other devices and the application area is low. The disadvantage of manual soldering is that it cannot meet many soldering requirements. For example, if the substrate is more than 2.0mm thick and has a large internal grounding layer, manual soldering can hardly be completed. In the industry standard, level 3 electronic products require 75% through-tin, but it is difficult to measure and inspect whether the 75% through-tin standard is met, and the evaluation of this standard is often controversial. And due to the influence of the ground layer of the board, it is even more difficult to achieve the requirement of 75% tin penetration. [0003] In addition,...

AI Technical Summary

Problems solved by technology

The disadvantage of wave soldering is that there is interference from other devices and the applicable surface is low

The disadvantage of manual soldering is that it cannot meet many soldering requirements, such as substrates with a thickness of more than 2.0mm and a large-area grounding layer inside, manual soldering is almost impossible to complete

In the industry standard, level 3 electronic products require 75% through-tin, but it is difficult to measure and inspect whether to meet the 75% through-tin standard, and there are often disputes over the evaluation of this standard

And due to the influence of the ground layer of the board, it is even more difficult to achieve the requirement of 75% tin penetration

[0003] In addition, for military products, most of them meet the welding requirements of Class 3 electronic products, and there are many varieties in small batches, and the product structure is relatively complicated. Manual welding cannot meet the welding requirements, and wave soldering is not applicable. The thickness of the board is large, and most of them are plug-ins. Due to the large current during use, the requirements for noise reduction and heat dissipation of the device are high. As a result, the heat dissipation performance and overcurrent capability of the printed board must be paid attention to during the design process of the printed board. Currently, noise reduction and heat dissipation The method is to use a large area of ​​ground copper between the signal layer and the power layer, and the improvement of the heat dissipation performance of the printed board will greatly increase the difficulty of soldering manufacturability. It is difficult for welding equipment (such as electric soldering iron) in daily production. Meet the requirement of 75% through-tin

[0004] In addition, in the existing technology, the adjustment function of the selective welding carrier is weak, and the carrier is underutilized, and only one printed board can be loaded at a time. Assuming that 100 printed boards need to be welded, 100 times of loading and unloading processes are required. The preheating light tube of the machine needs to be opened 100 times and closed 100 times, and the corresponding preheating time should be multiplied by 100 times, which accelerates the aging of the preheating light tube

[0005] Moreover, the existing carriers are generally aimed at a specific type of product, and the versatility is low. Due to the wide variety of circuit boards, the size, structure, and component layout of different circuit boards are very different, and the special trays are generally not universal.

The cost of special-purpose carriers is high. On the one hand, since each special-purpose pallet is only suitable for one type of circuit board, the manufacturing cost for the pallet will be very high

On the other hand, there are a large number of special trays for maintenance and management, and the utilization rate is low, which will bring many problems to the management of the production site. Increased production management costs

There is also a universal vehicle in the prior art, but it is heavy and the utilization rate is not high

Images