Manufacturing method of high-corrosion-resistance thick-film resistor

Abstract

The invention discloses a manufacturing method of a high-corrosion-resistance thick-film resistor, which comprises the following steps of: S1, printing a back electrode and a front electrode on a substrate, and sintering and curing; s2, printing a resistive layer on the substrate between the two front electrodes, and sintering and curing; s3, printing a glass layer on the resistive layer and a part of the front electrode, and sintering and curing; s4, performing laser resistance trimming on the resistance layer; s6, printing a first resin protection layer on the glass layer and a part of the front electrode, and curing the first resin protection layer; s7, arranging strips, and carrying out vacuum coating on the end parts; s8, carrying out grain folding and end part coating; the method is characterized by further comprising the following steps between the step S6 and the step S7: A1, chemically plating high-phosphorus nickel on the surfaces of the exposed front electrode and the back electrode; and A2, printing a second resin protection layer on the first resin protection layer and a part of the front electrode, and curing. The corrosion resistance of the resistor is improved, and the service life of the resistor is prolonged.

Description

Technical Field

[0001] The invention relates to a resistor, and in particular to a method for manufacturing a high corrosion-resistant thick film resistor. Background Art

[0002] Resistors are electronic components that hinder the flow of current. Chip resistors are a type of resistor. Chip resistors are also called name card fixed resistors and are a type of metal glass glaze resistors. They are made by mixing metal powder and glass glaze powder and printing them on a substrate using screen printing. They are resistant to moisture and high temperatures and have a small temperature coefficient. They can greatly save circuit space costs and make the design more refined.

[0003] When the resistor is used in harsh corrosive environments such as seawater, acid or alkaline, external water vapor penetrates into the resistor film layer through the gaps at the terminals, and at the same time brings impurity ions to the resistor layer. The impurity ions and the aqueous solution form an electrolyte, and the metal silver and other metals form positive and negative electrodes to form a primary battery, causing the resistor film to corrode and fail, thereby greatly shortening the life of the resistor. Therefore, how to solve the above technical problems is the direction that technicians in this field need to work hard on. Summary of the invention

[0004] The present invention aims to provide a method for manufacturing a high corrosion-resistant thick film resistor. By using this method, the corrosion resistance of the resistor can be effectively improved and the service life of the resistor can be extended.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for manufacturing a high corrosion-resistant thick film resistor, the steps of which are:

[0006] S1, printing the back electrode and the front electrode on the substrate, and sintering and curing them;

[0007] S2, printing the resistance layer on the substrate between the two front electrodes, and sintering and curing;

[0008] S3, printing a glass layer on the resistance layer and part of the front electrode, and sintering and curing;

[0009] S4, laser trimming the resistance of the resistor layer;

[0010] S6, printing a first resin protective layer on the glass layer and a portion of the front electrode, and curing the first resin protective layer;

[0011] S7, vacuum coating of strips and ends;

[0012] S8, folding grains and end coating;

[0013] The following steps are also provided between step S6 and step S7:

[0014] A1: Electroless plating of high-phosphorus nickel on the exposed front electrode and back electrode surfaces;

[0015] A2. Print a second resin protective layer on the first resin protective layer and a portion of the front electrode, and cure the layer.

[0016] In the above technical solution, in step A1, the first resin layer is first masked with a masking agent, and then nickel is plated on the exposed front electrode and the back electrode with a chemical nickel plating solution, and then dried.

[0017] In the above technical solution, step A1 includes the following steps:

[0018] B 1. Use a degreasing agent to degrease the exposed front electrode and back electrode, and then remove the degreasing agent;

[0019] B2, palladiumizing the exposed front electrode and back electrode using palladium solution;

[0020] B3. Wash away the excess palladium solution;

[0021] B4. Place the resistor in a nickel bath for chemical nickel plating.

[0022] In the above technical solution, in step B1, hydrochloric acid is used to wash away excess degreasing agent.

[0023] In the above technical solution, the hydrochloric acid is 10% hydrochloric acid.

[0024] In the above technical solution, in step B3, the excess palladium chloride solution is washed away with pure water and then dried.

[0025] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0026] 1. In the present invention, high-phosphorus nickel is chemically plated on the surface of the front electrode and the outer electrode, that is, a layer of high-phosphorus nickel is evenly plated, thereby increasing the compactness of the front electrode and the back electrode, improving the corrosion resistance of the resistor, and effectively extending the life of the resistor;

[0027] 2. In the present invention, a phosphating passivation film will be formed on the surface of the high-phosphorus nickel. The passivation film is formed quickly and can be repaired immediately after being damaged. It has good protective performance, effectively improves the corrosion resistance of the resistor, and prolongs the service life of the resistor;

[0028] 3. The high-phosphorus nickel in the present invention can not only protect the front electrode and the back electrode, but also make the front electrode and the back electrode denser and more tightly bonded to the resin layer, thereby reducing the gap between the front electrode, the back electrode and the resin layer, further improving the corrosion resistance of the resistor and extending its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is an electron microscope image of the front electrode and the back electrode of the resistor in the first embodiment of the present invention;

[0030] Figure 2 It is an electron microscope image of the front electrode and the back electrode of the resistor in the prior art. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0032] Example 1: See Figure 1 , 2 As shown, a method for manufacturing a high corrosion-resistant thick film resistor comprises the following steps:

[0033] S1. Printing a back electrode and a front electrode on a substrate, and sintering and curing them; wherein the main material of the front electrode and the back electrode is silver, and the silver paste is printed on both ends of the front side and both ends of the back side of the substrate respectively, and the silver paste at both ends of the front side of the substrate forms the front electrode after sintering and curing, and the silver paste at both ends of the back side of the substrate forms the back electrode after sintering and curing.

[0034] S2. Print the resistor layer on the substrate between the two front electrodes and sinter and solidify it; wherein the resistor layer is printed on the front side of the substrate, between the two front electrodes, and the two ends of the resistor layer are respectively overlapped on the partial front sides of the front electrodes on both sides, so that the two front electrodes connect the two ends of the resistor layer.

[0035] S3, printing a glass layer on the resistor layer and part of the front electrode, and sintering and curing; the glass layer completely covers the front surface of the resistor layer, and both ends of the glass layer also cover the front surface of part of the front electrode respectively, which plays a role in protecting the resistor layer;

[0036] S4, laser trimming the resistance layer to adjust the resistance to reach a preset resistance value;

[0037] S6. Print a first resin protective layer on the glass layer and part of the front electrode, and cure it; the first resin protective layer completely covers the glass layer, and both ends of the first resin protective layer also cover the front of part of the front electrode. The glass layer and the first resin protective layer are used to protect and insulate the resistor layer, and also have strong high temperature resistance and heat dissipation performance, improve the high temperature resistance and heat dissipation energy of the resistor, and improve the stability of the resistor under high temperature conditions.

[0038] S7, chemically plating high-phosphorus nickel on the exposed front electrode and the back electrode surface; wherein, since the first resin protective layer covers part of the front electrode, after the first resin protective layer is made, chemically plating high-phosphorus nickel is then performed on the outer surface of the back electrode and the outer surface of the front electrode not covered by the first resin protective layer, that is, a layer of high-phosphorus nickel is covered on the outer surface of the front electrode and the back electrode. Since the roughness of high-phosphorus nickel is very small and the density is high, the charge transfer resistance in the sodium chloride solution is increased, which can greatly delay the corrosion of the front electrode and the back electrode, thereby greatly enhancing the corrosion resistance of the resistor and extending the service life of the resistor;

[0039] S8, printing a second resin protective layer on the first resin protective layer and part of the front electrode, and curing; the second resin protective layer completely covers the outside of the first resin protective layer, and the two ends respectively cover the front of part of the front electrode, which can not only further protect the first resin protective layer, but also block the gap between the high-phosphorus nickel and the first resin protective layer, reduce corrosion to the resistor layer, and extend the service life of the resistor;

[0040] S9, strip arrangement and end vacuum coating; since the entire substrate is large in size, multiple resistors will be made at the same time, therefore, it is cut into strips, each strip of material has multiple arranged resistors, and the cutting part will expose both ends of all resistors, that is, the front electrode and the back electrode at both ends of the resistor layer are respectively located at the outer ends of the strip material, and then the two ends of the adjustment material are vacuum coated to connect the front electrode and the back electrode at the corresponding end of the resistor;

[0041] S10, folding and end coating; folding the strip material after vacuum coating, that is, separating the multiple resistors connected together, and performing end coating on the vacuum coating layer at both ends of the resistor to make terminals at both ends of the resistor.

[0042] The chemical high-phosphorus nickel plating in step S7 comprises the following steps:

[0043] B 1. Use a degreasing agent to degrease the exposed front electrode and back electrode, use pure water to clean the dirt on the front electrode and back electrode, and then remove the degreasing agent; this can remove the first resin protective layer that may remain on the front electrode and back electrode during the printing and drying process.

[0044] At the same time, 10% hydrochloric acid is used to wash away excess degreasing agent. The hydrochloric acid can not only remove the excess degreasing agent, but also provide an acidic environment for the front electrode and the back electrode.

[0045] B2. Use palladium chloride solution to palladiumize the exposed front electrode and back electrode. Since hydrochloric acid is used to remove excess degreasing agent, an acidic environment is provided to the front electrode and back electrode, so that active sites are provided for the subsequent nickel oxidation when the palladium chloride solution is used.

[0046] B3. Use pure water to wash away the excess palladium solution;

[0047] B4. Place the resistor in a nickel bath for chemical nickel plating.

[0048] The palladium solution is acidic stannous chloride, which is mainly used to achieve better adhesion of nickel.

[0049] In order to facilitate chemical nickel plating of the front electrode and the back electrode, before chemical nickel plating (after step B3 and before step B4), the first resin layer is first masked with a masking agent (the chemical masking agent is mainly EDTA or DTPA, which does not need to be removed later), and then nickel is plated on the exposed front electrode and the back electrode using a chemical nickel plating solution (the chemical nickel plating solution contains nickel and phosphorus), and then dried. The setting of the masking agent can prevent the chemical nickel plating solution from being plated on the first resin protective layer, reducing the loss of nickel and phosphorus in the chemical nickel plating solution.

[0050] In the present invention, taking the production of 0805 type resistor as an example, first, silver paste is used to print the front electrode and the back electrode, and after high-temperature plastic firing at 900°C, resistor paste (resistance layer) is printed, and a 100Ω resistor is obtained after a high temperature of 900°C, and then a glass layer is printed, and laser correction is performed after drying and plastic firing at 500°C, and then a first resin layer is printed. After drying at 150°C, the first resin layer is masked with a masking agent, and then nickel solution is used to chemically plate high-phosphorus nickel on the front electrode and the back electrode. After drying, the second resin layer is printed, and after curing at 150°C, striping, vacuum coating, and folding are performed, and finally, electroplating technology is used to perform end coating.

[0051] like Figure 1 As shown, it is an electron microscope image of the front electrode and the back electrode of the resistor made according to the process. Figure 2 This is an electron microscope image of the front electrode and the back electrode in a conventional resistor. It can be clearly seen that the surface layer of the front electrode and the back electrode of the resistor in this application has a dense phosphating passivation film, which is formed quickly and can be repaired immediately after being damaged, and has good protection performance. In addition, it not only protects the front electrode and the back electrode made of silver paste, but also makes the surface of the front electrode and the back electrode denser, and makes the front electrode and the first resin protective layer and the second resin layer more tightly bonded, reducing the gap between the front electrode and the first resin protective layer and the second resin protective layer, thereby improving the corrosion resistance of the resistor.

[0052] After the conventional resistor and the resistor made in the present application were subjected to a 200-hour salt spray test, the conventional resistor had begun to fail, while the high corrosion-resistant thickness resistor in the present application continued to be subjected to the salt spray test until 1200 hours later. The performance of the corrosion-resistant resistor exceeded the specification line to some extent (if the data exceeds this specification line, the corresponding data is unqualified, and the corresponding performance fails or is unstable), but no obvious corrosion phenomenon was found on its surface. Therefore, in the present invention, the corrosion resistance of the resistor is better and the service life is longer.

[0053] In this document, the terms "comprises," "comprising," or any other variations thereof, are intended to cover a non-exclusive inclusion of elements other than those listed and may also include additional elements not expressly listed.

[0054] In this document, the directional words such as front, back, top, and bottom are defined by the positions of the components in the drawings and the positions of the components relative to each other, and are only for the sake of clarity and convenience in expressing the technical solution. It should be understood that the use of the directional words should not limit the scope of protection claimed in this application.

[0055] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a high corrosion resistance thick film resistor, the steps of which are: S1, printing the back electrode and the front electrode on the substrate, and sintering and curing them; S2, printing the resistance layer on the substrate between the two front electrodes, and sintering and curing; S3, printing a glass layer on the resistance layer and part of the front electrode, and sintering and curing; S4, laser trimming the resistance of the resistor layer; S6, printing a first resin protective layer on the glass layer and a portion of the front electrode, and curing the first resin protective layer; S7, vacuum coating of strips and ends; S8, folding grains and end coating; its characteristics are: The following steps are also provided between step S6 and step S7: A1: Electroless plating of high-phosphorus nickel on the exposed front electrode and back electrode surfaces; A2. Print a second resin protective layer on the first resin protective layer and a portion of the front electrode, and cure the layer.

2. The method for manufacturing a high corrosion-resistant thick film resistor according to claim 1, characterized in that: In the step A1, the first resin layer is first masked with a masking agent, and then nickel is plated on the exposed front electrode and the back electrode with a chemical nickel plating solution, and then dried.

3. The method for manufacturing a high corrosion-resistant thick film resistor according to claim 1, characterized in that: The step A1 includes the following steps: B 1. Use a degreasing agent to degrease the exposed front electrode and back electrode, and then remove the degreasing agent; B2, palladiumizing the exposed front electrode and back electrode using palladium solution; B3. Wash away the excess palladium solution; B4. Place the resistor in a nickel bath for chemical nickel plating.

4. The method for manufacturing a high corrosion-resistant thick film resistor according to claim 3, characterized in that: In the step B1, hydrochloric acid is used to wash away excess degreasing agent.

5. The method for manufacturing a high corrosion-resistant thick film resistor according to claim 4, characterized in that: The hydrochloric acid is 10% hydrochloric acid.

6. The method for manufacturing a high corrosion-resistant thick film resistor according to claim 3, characterized in that: In step B3, the excess palladium solution is washed away with pure water and then dried.

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