Manual welding method for gold-plated circuit of microwave component

Abstract

The invention discloses a manual welding method for a gold-plated circuit of a microwave component, which belongs to the field of welding and assembling of microwave components and comprises the following steps of: (1) preheating a welded piece; (2) an electric soldering iron, a gold-tin welding rod and a soldering flux are adopted for welding; the welding method provided by the invention has a wide process window: the preheating temperature and the welding temperature are relatively wide; by adopting the gold-tin welding rod for welding, the production cost is reduced, and compared with gold-tin soldering paste, the process cost of the gold-tin welding rod is reduced by about 50%; no splashing phenomenon exists during welding; welding is simple, pretreatment is not needed, the temperature returning time before gold-tin soldering paste welding is shortened, therefore, the whole production time is shortened, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave component welding and assembly, and particularly to a manual welding method for gold-plated circuits of microwave components. Background Art

[0002] Currently, with the increasingly strict application environments of microwave components (including power dividers, couplers, circulators, amplifiers, etc.) and the increasing power requirements, they are required to work highly reliably for a long time in large extreme environmental temperatures, which puts forward high-reliability requirements for the welding interconnection of gold-plated circuits in microwave components.

[0003] Commonly, high-temperature solders are used to weld the gold-plated circuits of microwave devices to meet the harsh use environments. Gold-tin solder has become the preferred solder for microwave component interconnection due to its advantages such as high strength and high thermal conductivity. However, currently, gold-tin solder is often used in the forms of solder sheets and solder pastes. Solder sheets are commonly used for chip heat sink welding, and the remaining use environments adopt gold-tin solder paste welding, avoiding the operation of removing gold from the gold-plated circuit. Circuit or structural components often use solder paste welding. The reason for generally using gold-tin solder paste in the prior art is that the solder paste comes with a flux and is a shelf product.

[0004] However, currently, the method of using gold-tin solder paste for welding has at least the following disadvantages: (1) Gold-tin solder paste is expensive. Domestic gold-tin solder paste is generally about 1000 yuan / g, and imported gold-tin solder paste is generally about 2500 yuan / g; (2) Gold-tin solder paste has high storage requirements and needs to be stored at low temperature; (3) Although domestic gold-tin solder paste is relatively cheap, its wettability is poor, and it is easy to generate splashing phenomena during welding, resulting in contamination of non-welding areas; (4) It is difficult to add gold-tin solder paste during circuit welding, and the flux remaining after high-temperature welding of gold-tin solder paste is difficult to clean, making it impossible to achieve efficient welding. Summary of the Invention

[0005] The purpose of the present invention is to provide a manual welding method for gold-plated circuits of microwave components to solve the above problems.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A manual welding method for gold-plated circuits of microwave components includes the following steps: (1) Preheat the workpiece to be welded; (2) Use an electric soldering iron, a gold-tin welding rod, and a flux for welding; (3) Use a sponge cotton swab to adsorb and clean the flux.

[0007] The welding method of the present invention can achieve efficient, high-quality, and low-cost welding of the structural components of the gold-plated circuits of microwave components.

[0008] When manufacturing gold-tin solder rods, it is impossible to add flux, unlike tin-lead solder rods. Moreover, the solder rods are hard and brittle, cannot be wound into coils, and gold-tin solder rods need to be customized, with no off-the-shelf products. When using gold-tin solder rods, the solder rods need to be customized according to the actual situation of the welded product to explore the welding process.

[0009] In addition to the process parameters of using gold-tin solder rods for welding in the present invention, the cleaning of the flux is also an important improvement. A sponge is used to adsorb the un-solidified flux, reducing the intensity of subsequent cleaning work.

[0010] In the preferred technical solution, the preheating temperature of the welded part is 220°C ± 10°C. When the welded part is relatively large (the size of the welding preheating body is φ100 - φ150mm), the preheating temperature can be increased to 260°C ± 10°C. For particularly large welding devices (the size of the welding preheating body is φ200 and above), it is required that the actual temperature at the welding point is higher than 170°C for welding operations; the preheating time is 5 - 10 minutes.

[0011] The main function of preheating is to increase the basic temperature at the solder joint. Generally, manual gold-tin welding requires the basic temperature at the solder joint position to be increased to 180°C and above, which can reduce the welding time during welding and achieve good wetting.

[0012] Preferably, the welding temperature of the soldering iron is required to be 360°C ± 10°C. A high-power soldering iron is used, and a soldering iron pen with a power of more than 200W is selected for welding; Preferably, when welding, hold the soldering iron in one hand and the gold-tin solder wire in the other hand for convenient operation; the flux is selected as a rosin-based high-temperature flux; During welding, first let the soldering iron tip take in solder, then dip the solder wire into the flux, and weld the welded part. The welding time is less than 30s. When the solder at the solder joint has solidified but the flux has not solidified, use a dust-free purification sponge cotton swab to adsorb the flux, reducing the subsequent cleaning difficulty. Only anhydrous ethanol is used for cleaning.

[0013] As a preferred technical solution: The soldering iron is preferably the 250W high-power constant-temperature soldering station of WX1 of Weller in Germany, equipped with a WXP200 soldering iron pen, and the soldering iron tips are selected as XHT C and XHT D soldering iron tips, selected according to the size of the solder joint.

[0014] As a preferred technical solution: The gold-tin solder rods are selected in the specifications of 0.4mm * 0.4mm * 100mm or 0.5mm * 0.5mm * 100mm. The main reason for selecting this specification is that the gold-tin solder is hard and brittle, and this length is convenient for production and operation.

[0015] As a preferred technical solution: For the rosin-based high-temperature flux, the TSP-TSHT025 type flux is preferably selected, with an active temperature of 200 - 300°C. This flux is milky white, and the flux solidifies slowly after welding, which is convenient for adsorption and cleaning; As a preferred solution: for the cotton swabs adsorbed with flux after welding, SW-874C and SW847D type dust-free sponge cotton swabs are preferred.

[0016] Compared with the prior art, the advantages of the present invention are as follows: (1) The welding method of the present invention has a wide process window, and both the preheating temperature and the welding temperature are relatively wide, making it easier to operate; specifically, when using gold-tin solder paste for welding, generally a hot air gun at 400 °C is used to blow hot air on the solder joints for heating, and then a soldering iron is used in cooperation. The preheating temperature needs to be above 300 °C and the welding point needs to be above 200 °C for convenient welding, and it is very difficult to add solder when using a soldering iron. (2) The present invention uses a gold-tin welding rod for welding to reduce production costs: the gold-tin welding rod is only 560 yuan / g, and the waste of the gold-tin welding rod is small. The welding tailings can be filled by clamping with tweezers and almost all can be used up; while there are losses in the syringe and during the addition when using gold-tin solder paste. Compared with gold-tin solder paste, the process cost of the gold-tin welding rod of the present invention is reduced by about 50%. (3) The welding is simple. The welding time of the gold-tin welding rod is shorter than that of the gold-tin solder paste. It is convenient to add solder, and no pretreatment is required, reducing the warm-up time before gold-tin solder paste welding, thus reducing the entire production time and improving production efficiency. (4) There is no splash phenomenon during the welding of the method of the present invention, overcoming the defect of splash during gold-tin paste welding. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the welding structure of Embodiment 1 of the present invention; Figure 2 It is; an X-ray inspection result diagram after welding in Embodiment 1 of the present invention; Figure 3 It is a schematic diagram of the welding structure of Embodiment 2 of the present invention; Figure 4 It is an X-ray inspection result diagram after welding in Embodiment 2 of the present invention; In the figure: 1, gold-plated circuit; 2, circuit connection column; 3, circuit connector; 4, cavity. Detailed Embodiments

[0018] The present invention will be further described below in conjunction with embodiments.

[0019] Embodiment 1: A manual welding method for the gold-plated circuit of a microwave component, As Figure 1 shown, in this embodiment, the gold-plated circuit 1 and the circuit connection column 2 are welded. Among them, the material of the circuit 1 is 2A12 aluminum, nickel-plated copper-gold, 3 μm of nickel, 8 μm of copper, and 2 μm of gold; the material of the circuit connection column 2 is brass, copper-plated gold, 3 μm of copper, and 1.5 μm of gold. The nickel layer of the electroplated layer on the aluminum substrate mainly improves the adhesion between the coating and the substrate. The copper layer mainly reduces the loss caused by the skin effect of microwave signals in the microwave circuit. Therefore, the copper layer needs to have a high thickness. The gold layer plays a role in surface protection and welding layer of the microwave circuit. When considering cost and subsequent repair situations, a thinner gold layer is selected for the gold plating layer. If the gold layer is too thick, the gold content in the solder joint after welding will be too high, and the reflow temperature will increase by more than 30°C during repair, and the fluidity of the solder will decrease.

[0020] In this embodiment, the diameter of the solder joint coverage is φ2.2mm, and the through-tin clearance for the interconnection welding design is +0.04mm. This embodiment preheats at 220°C for 5 minutes, welds at a welding temperature of 350°C for 20 seconds, and uses a chisel-shaped soldering iron tip with a width of 3.2mm for welding. The operation record combines the gold-plated circuit 1 and the circuit connection post 2 to form a welding combination. The preheating fixture fixes the combination and places it on the heating table for preheating. The temperature of the heating table is set at 220°C. After preheating for 5 minutes, welding is carried out. The temperature of the soldering iron is set at 350°C. First, tin the soldering iron tip. Dip the gold-tin welding rod in the flux and place it on the head of the soldering iron tip so that a layer of tin adheres to the head of the soldering iron tip. After tinning, start welding. Hold the gold-tin welding rod in the left hand and dip it in the flux, hold the soldering iron in the right hand, and weld the solder joint. Add the gold-tin welding rod during the welding process. When the solder joint is full, withdraw the soldering iron and the welding rod. Control the welding time within 20 seconds. Immediately use a sponge cotton swab to adsorb the flux after observing the solder solidify. After cleaning the flux, remove the welded part from the heating table and let it cool.

[0021] The effect diagram after welding is shown in Figure 2 as shown, from Figure 2 it can be seen that the penetration rate has reached more than 95%.

[0022] Embodiment 2 A manual welding method for a gold-plated circuit of a microwave component, as Figure 3 shown, in this embodiment, the gold-plated circuit 1 is welded to the center conductor of the circuit connector 3; Among them, the material of the gold-plated circuit (1) is 2A12 aluminum, nickel-plated copper-gold, nickel 5μm, copper 15μm, gold 3μm; the material of the pin of the circuit connector 3 is beryllium bronze, copper-gold plated, copper 3μm, gold 2μm; the material of the cavity 4 is aluminum, and the cavity 4 plays a role in fixing the circuit connector 3 and supporting the gold-plated circuit 1; In this embodiment, the solder joint coverage area is 6mm * 1.7mm, and the through-tin clearance for the interconnection welding of the pin of the circuit connector 3 and the gold-plated circuit 1 is +0.08mm. This embodiment preheats at 260°C for 10 minutes, welds at a welding temperature of 370°C for 30 seconds, and uses a chisel-shaped soldering iron tip with a width of 5.0mm for welding. The effect diagram after welding is shown in Figure 4 as shown, from Figure 4 it can be seen that the penetration rate has reached 100%.

[0023] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A manual soldering method for gold-plated circuits of microwave components, characterized in that: The steps include: (1) Preheat the welded parts; (2) Use a soldering iron, gold-tin solder rod and flux for soldering.

2. The method according to claim 1, characterized in that In step (1), the preheating temperature of the welded part is 220°C ± 10°C. When the welded part is large, the preheating temperature can be increased to 260°C ± 10°C. For particularly large welded parts, the actual temperature at the welding point is required to be higher than 170°C before welding can be performed.

3. The method according to claim 1, characterized in that In step (1), the preheating time is 5 to 10 minutes.

4. The method according to claim 1, characterized in that: In step (2), the soldering temperature of the electric soldering iron is 360°C ± 10°C, and the power of the electric soldering pen is above 200W.

5. The method according to claim 1, characterized in that In step (2), the gold-tin soldering rod is selected to have a specification of 0.4 mm×0.4 mm×100 mm or 0.5 mm×0.5 mm×100 mm.

6. The method according to claim 1, characterized in that In step (2), the soldering flux is a rosin-based high-temperature soldering flux with an active temperature of 200-300°C.

7. The method according to claim 1, characterized in that In step (2), during welding, the soldering iron tip is first tinned, and then the gold-tin solder rod is dipped in flux to weld the workpiece. The welding time is less than 30 seconds. After the metal at the soldering point solidifies but the flux has not yet solidified, the flux is adsorbed and cleaned after welding.

8. The method according to claim 7, characterized in that Use dust-free purification sponge swab to absorb flux.

9. The method according to claim 8, characterized in that Use anhydrous ethanol for cleaning.

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