Method for avoiding color change of thin film circuit coating

Abstract

The invention discloses a method for preventing a plating layer of a thin film circuit from discoloring, and relates to the technical field of welding assembly processes, in particular to a method for connecting a soldering lug between a slide glass and a substrate, cutting off the corresponding soldering lug below a thin film circuit at the edge of the substrate, reducing the size by 1-2mm compared with the original size, and preventing the soldering lug from protruding out of the lower part of the substrate. Corresponding soldering lugs below a substrate edge circuit are cut off, the edge alignment mode during vacuum welding of the substrate and a slide glass is adjusted, the soldering lugs are prevented from protruding below the substrate, and the problem of color change of a product circuit in the welding process can be avoided; the method is simple and practical, the first pass yield of products is improved, the manufacturing cost is reduced, and the method is suitable for mass production of the devices.

Description

Technical Field

[0001] The invention relates to the technical field of welding assembly process, in particular to a method for preventing discoloration of a thin film circuit coating. Background Art

[0002] With the development of active phased array radar technology, T / R components are increasingly showing a trend of high power and light weight. Microstrip ring spacer components are important devices that perform dual functions of transmitting and receiving in T / R components and must meet the requirements of "small, light, and highly reliable".

[0003] The RF device is made of a substrate and a carrier welded in a vacuum eutectic furnace. The welding pieces of some products contain metal indium. Indium, with the element symbol In, atomic number 49, and melting point 156.51°C, is a silvery white and slightly bluish metal with a very soft texture and good ductility. Because the welding temperature is significantly higher than its melting point, the liquid metal indium will adhere to the surface of the device and leave black marks; when a very small amount of metal indium vapor condenses on the metal surface, it will cause the circuit surface to change color. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for preventing the discoloration of the coating of a thin film circuit, and the technical solution thereof is as follows.

[0005] The solder pad connects the carrier and the substrate, and the corresponding solder pad under the thin film circuit at the edge of the substrate is cut off, which is 1-2mm smaller than the original size to prevent the solder pad from protruding under the substrate.

[0006] Furthermore, when the carrier and the substrate are welded, a tooling is used for pressing.

[0007] Furthermore, the compacting pressure is 0.04-0.06 MPa.

[0008] Furthermore, a vacuum eutectic furnace is used for welding, and the furnace temperature is 20-30°C higher than the melting point of the solder piece. When the solder piece is melted, the vacuum degree in the furnace is not higher than 10mbar.

[0009] Furthermore, the soldering process uses flux on the soldering surfaces.

[0010] Furthermore, the thickness of the welding sheet is 30um~150um.

[0011] Furthermore, the solder sheet contains In.

[0012] Preferably, the welding sheet is 25In75Pb.

[0013] Furthermore, the reduced shape is a semicircle or an arc.

[0014] Furthermore, the surface of the carrier is coated with a solderable coating, the upper surface of the substrate has a thin film circuit, and the lower surface has a solderable coating.

[0015] Preferably, the solderable coating is a CuNiAu composite coating.

[0016] Compared with the prior art, the present invention has the following beneficial effects: By cutting off the corresponding solder pads under the circuit at the edge of the substrate, i.e. reducing the size by 1-2mm, adjusting the edge alignment method of the substrate and the carrier during vacuum welding, and preventing the solder pads from protruding under the substrate, the problem of discoloration of the product circuit during the welding process can be avoided; The invention is simple and practical, improves the product pass rate, reduces the manufacturing cost, and is suitable for mass production of such devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of assembly welding in the present invention; Figure 2 It is a schematic diagram of solder tab removal; Figure 3 Schematic diagram of the stacking and misalignment of the carrier and substrate assembly.

[0018] Among them, 1 is the substrate, 2 is the carrier, and 3 is the solder pad. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further explained below in conjunction with the accompanying drawings. The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "tooling", "assembly", "welding", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] like Figure 1As shown, the present invention provides a method for preventing discoloration of a thin film circuit coating, comprising a carrier 1 with a solderable coating on its surface, a substrate 2 with a solderable coating, and a welding sheet 3. The carrier 1 and the substrate 2 are welded in a vacuum eutectic furnace using an In-containing welding sheet, and the thickness of the welding sheet can be from 30um to 150um according to product requirements.

[0022] When welding in a vacuum eutectic furnace, the furnace temperature is 20~30℃ higher than the melting point of the solder. When the solder melts, the vacuum degree in the furnace is not higher than 10mbar.

[0023] Whether flux is used in the welding process depends on the product's requirements for weld penetration. Generally, products with high weld penetration require the addition of flux.

[0024] When substrate 1 and carrier 2 are welded, they are pressed by a tooling. Taking a welding area of ​​100mm² as an example, the pressure range of the tooling is 400~600g, that is, the pressure applied to the product is 0.04~0.06MPa.

[0025] like Figure 2 As shown in the figure, the corresponding soldering pad under the edge circuit is cut off, which is 1-2mm smaller than the original size. The cutting can be in an arc shape or other shapes. At the same time, when the product is assembled, the edges of the substrate and the carrier are aligned after being stacked, and the soldering pad is retracted instead of protruding directly under the substrate, as shown below Figure 3 As shown. It is 1-2mm smaller than the original size.

[0026] After welding, it was found that blackening occurred at the edge circuit without using the method of the present invention, but after reducing the size, no such phenomenon occurred, and the welding condition was good.

[0027] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

[0028] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified and replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preventing discoloration of a thin film circuit coating, wherein a soldering sheet is connected between a carrier and a substrate, characterized in that: Cut off the corresponding solder pads under the thin film circuit at the edge of the substrate, reducing them by 1-2mm compared to the original size, to prevent the solder pads from protruding under the substrate.

2. The method for preventing discoloration of a thin film circuit coating according to claim 1, characterized in that: When the carrier and substrate are welded, they are pressed tightly using tooling.

3. The method for preventing discoloration of a thin film circuit coating according to claim 2, characterized in that: The compacting pressure is 0.04-0.06 MPa.

4. The method for preventing discoloration of a thin film circuit coating according to claim 1, characterized in that: Vacuum eutectic furnace welding is used, and the furnace temperature is 20~30℃ higher than the melting point of the solder. When the solder is melted, the vacuum degree in the furnace is not higher than 10mbar.

5. The method for preventing discoloration of a thin film circuit coating according to claim 1, characterized in that: The soldering process uses flux on the soldering surfaces.

6. The method for preventing discoloration of a thin film circuit coating according to claim 1, characterized in that: The thickness of the welding sheet is 30um~150um.

7. The method for preventing discoloration of a thin film circuit coating according to claim 1, characterized in that: The soldering sheet contains metal indium.

8. The method for preventing discoloration of a thin film circuit coating according to claim 7, characterized in that: The reduced shape is a semicircle or an arc.

9. The method for preventing discoloration of a thin film circuit coating according to claim 1, characterized in that: The surface of the carrier is coated with a solderable coating, the upper surface of the substrate has a thin film circuit, and the lower surface has a solderable coating.

10. The method for preventing discoloration of a thin film circuit coating according to claim 9, characterized in that: The solderable coating is a CuNiAu composite coating.

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