A nitrogen protection device for wave soldering

Abstract

The invention discloses a wave soldering nitrogen protection device, comprising an aeration pipe installation frame and an aeration pipe, wherein the first end of the aeration pipe is connected to an air guide pipe by welding, the second end of the aeration pipe is closed and a fixing portion is arranged on the end, the first end of the aeration pipe is provided with a protective sleeve at a welding position, a through hole and a threaded portion are arranged on a first side plate of the aeration pipe installation frame, the protective sleeve of the aeration pipe is arranged to pass through the through hole, and the first end of the aeration pipe is fixed on the first side plate by matching with a nut and the threaded portion, a positioning hole is arranged on the second side plate of the aeration pipe installation frame, and the fixing portion is matched in the positioning hole.

Description

Technical Field

[0001] The invention relates to wave soldering, in particular to a nitrogen protection device for wave soldering. Background Art

[0002] Wave soldering has been around for nearly 70 years since it was invented in the 1950s. Because of its easy operation, high production efficiency, low cost and high reliability, it is currently widely used in the electronics field, especially in power supplies, home appliances, communications, automatic control, medical, military electronics and other fields. Wave soldering uses the constantly emerging tin liquid to fill the metal holes on the PCB board with the plug-in, and then cools and solidifies, and firmly solders the plug-in to the PCB board to achieve electrical functions. During the wave soldering process, due to the continuous rolling of the tin surface, the tin surface is easily oxidized when it comes into contact with the air, and tin slag is formed with tin dioxide as the crystal nucleus. The tin slag is not melted and needs to be treated regularly. This problem became particularly serious in 2006 when lead-free was introduced, because the welding temperature rose from 200 degrees to 240 degrees. Usually, the tin slag generated in a general shift is as high as 5kg. When encountering large boards or special processes, the amount of tin slag can reach 10kg or even 20kg per shift, which brings great waste to production.

[0003] Since 1970, wave soldering nitrogen protection devices have appeared one after another. The current designs are based on the three aeration tubes designed by Electrodefy of Canada in 1991, which are placed before the disturbance wave, between the disturbance wave and the flat wave, and after the flat wave to protect the fresh surface of the solder wave that rolls when it flows down from a high place and impacts the liquid surface. During the production process, the PCB board on the frame and the frame form a relatively closed space. The nitrogen generated by the aeration tube flows out slowly and covers the tin surface like a blanket. The oxygen concentration in this space can be controlled within 100ppm, which can basically reduce the generation of solder slag by more than 85%. Under good process control, it can even reduce the solder slag by more than 95%.

[0004] The aeration tube is sintered into a porous structure with a nanometer-level pore size, so as to ensure the uniformity of the gas coming out of the entire tube. The connection between the aeration tube and the air guide tube (usually made of 316 material) is welded to ensure air tightness. The other end of the aeration tube is sealed and threaded. Generally, the aeration tube is inserted from one side plate to the other side plate and fixed with screws at the other end. During the use of the wave soldering nitrogen protection device, a lot of flux remains on the tube. When the aeration tube is pulled out, the solder joint part is easy to be strained, the welding contact surface is small, and the solder joint position is easy to break, which affects the turnover of the aeration tube. Summary of the invention

[0005] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to prevent the aeration pipe and the air guide pipe from being broken at the welding point and to reduce the clogging of the aeration pipe by tin slag and solder resist.

[0006] To achieve the above-mentioned purpose, the present invention provides a wave soldering nitrogen protection device, including an aeration pipe mounting frame and an aeration pipe, the first end of the aeration pipe is connected to the air guide pipe by welding, the second end of the aeration pipe is closed and a fixing portion is provided at the end, the first end of the aeration pipe is provided with a protective sleeve at the welding position, a through hole and a threaded portion are provided on the first side plate of the aeration pipe mounting frame, the protective sleeve of the aeration pipe is configured to pass through the through hole, and the first end of the aeration pipe is fixed to the first side plate by a nut and the threaded portion, a positioning hole is provided on the second side plate of the aeration pipe mounting frame, and the fixing portion is fitted in the positioning hole.

[0007] Furthermore, a rear porous protective sleeve is arranged outside the aeration pipe.

[0008] Furthermore, the porous protective sleeve is made of high temperature resistant glass fiber material or Teflon material.

[0009] Furthermore, the pore size of the porous protective sleeve is at the micron level.

[0010] The present invention makes the welding point between the air guide pipe and the aeration pipe basically effortless, greatly reducing the probability of the welding point connection breaking. In addition, a protective sleeve is added to the welding point to improve the strength of the welding point connection, so that the probability of the welding point breaking is reduced from 10% to less than 1%. The porous protective sleeve has good air permeability and does not stick to tin or tin slag, so that the protective nitrogen can be evenly dispersed, preventing the tin slag and solder resist from clogging the aeration pipe, and the replacement is convenient and low-cost, thereby greatly improving the life of the aeration pipe.

[0011] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of an aeration pipe installation framework in a preferred embodiment of the present invention;

[0013] Figure 2 It is a schematic diagram of the working of the aeration pipe frame and the top cover in a preferred embodiment of the present invention;

[0014] Figure 3 is a top view of a top cover in a preferred embodiment of the present invention;

[0015] Figure 4 It is a schematic diagram of an aeration pipe case in a preferred embodiment of the present invention;

[0016] Figure 5It is a schematic diagram of an aeration pipe protection sleeve in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0017] The following describes several preferred embodiments of the present invention with reference to the drawings in the specification, so that the technical content is clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0018] Figure 1-3 A specific embodiment according to the present invention is shown. Figure 1 , 2 As shown in the figure, the aeration pipe 5 of the wave soldering machine is arranged on the frame 1, and the assembly edges 2 are arranged on both sides of the frame 1, and the assembly edges 2 are provided with assembly holes 3. The side of the frame 1 is also provided with a slag removal port 4 that can be opened and closed by a hinge 10. The frame 1 is fixed to the fixed track 15 of the wave soldering machine by bolts 9 through the assembly holes 3.

[0019] like Figure 2 As shown, the frame 1 is thus arranged above the tin furnace 11 filled with tin liquid 12 and the tin wave crest 13, and below the welding machine track 15. If maintenance or scooping of tin slag is required, the tin furnace 11 can be directly shaken down, and then the operation can be carried out. The slag removal port 4 on the side of the frame 1 is usually closed to ensure the internal protective gas concentration. When there is a lot of tin slag remaining, the slag removal port 4 can be opened to take out the tin slag. Preferably, a sampling tube can also be arranged next to the aeration pipe 5, so that the oxygen concentration in the frame 1 can be detected online or offline.

[0020] like Figure 2 , 3 As shown, a top cover 7 is also provided above the welding machine track 15, a hinge is provided on one side of the top cover 7, and a handle 17 is provided on the other side, so that the top cover 7 can be opened, and a high-temperature glass 6 is also provided on the top cover 7, so that the operator can observe the inside of the welding machine without opening the top cover 7. Preferably, an oxygen content test hole 18 is also provided on the top cover 7.

[0021] In the prior art, the aeration tube is sintered into a porous structure with a pore size of nanometer level, so as to ensure the uniformity of gas coming out of the entire tube. One end of the aeration tube is connected to the air guide tube by welding, and the other end of the aeration tube is sealed to ensure airtightness and set with threads. The aeration tube is inserted from one side panel to the other side panel, and fixed to the side panel by the threads at the closed end. Because a lot of flux will remain on the aeration tube during the use of wave soldering, when the aeration tube is pulled out, the solder joint part is easy to be strained and the welding contact surface is small, and the solder joint position may break, affecting the turnover of the aeration tube. In such as Figure 4In the embodiment shown, one end of the aeration tube 5 is connected to the air guide tube 25, and the other end is sealed and provided with a fixing portion 21. A through hole 20 and a threaded portion 23 are provided on the frame side plate 19, and the aeration tube 5 passes through the through hole 20, and the aeration tube 5 is fixed to the frame side plate 19 by the cooperation of the nut 24 and the threaded portion 23, and the other end of the aeration tube 5 is fixed to the positioning hole provided on the other side frame side plate through the fixing portion 21. In this way, the welding point between the air guide tube 25 and the aeration tube 5 is basically free of effort, which greatly reduces the probability of fracture at the welding point connection, so that the probability of welding point fracture is reduced from 10% to less than 1%.

[0022] like Figure 5 As shown, in a preferred embodiment of the present invention, a protective sleeve 26 is further provided outside the aeration pipe 5. The protective sleeve 26 is a micron-level porous material of high temperature resistant glass fiber or Teflon, which has good air permeability and does not stick to tin or tin slag. The advantages are that the protective nitrogen can be evenly dispersed to prevent tin slag and solder resist from clogging the aeration pipe, and the replacement is convenient and low cost, thereby greatly improving the life of the aeration pipe.

[0023] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A wave soldering nitrogen protection device, characterized in that: It comprises an aeration tube installation frame and an aeration tube; assembly edges are arranged on both sides of the aeration tube installation frame, assembly holes are arranged on the assembly edges, and a slag cleaning port which can be opened and closed by hinges is also arranged on the side of the aeration tube installation frame; the first end of the aeration tube is connected to the air guide tube by welding, the second end of the aeration tube is closed and a fixing part is arranged at the end, the first end of the aeration tube is provided with a protective sleeve at the welding position, a through hole and a threaded part are arranged on the first side plate of the aeration tube installation frame, the protective sleeve of the aeration tube is arranged to pass through the through hole, and the first end of the aeration tube is fixed to the first side plate by the cooperation of a nut and the threaded part, and a positioning hole is arranged on the second side plate of the aeration tube installation frame, and the fixing part cooperates in the positioning hole.

2. The wave soldering nitrogen protection device according to claim 1, wherein: A rear porous protective sleeve is also arranged outside the aeration pipe.

3. The wave soldering nitrogen protection device according to claim 2, wherein: The porous protective sleeve is made of high temperature resistant glass fiber material or Teflon material.

4. The wave soldering nitrogen protection device according to claim 3, wherein: The pore size of the porous protective sleeve is at the micron level.

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