A printing process for a thick film circuit board

Abstract

The present invention provides a printing process for a thick film circuit board. By controlling the mesh number of the screen of the screen printing machine in the printing process, the gap between the circuit board substrate and the screen of the screen printing machine, the pressure between the squeegee of the screen printing machine and the circuit board substrate, the drying time of the circuit board substrate, and the angle range between the moving direction of the squeegee and the length direction of the circuit board substrate, the thickness of the circuit board substrate and the thickness of the resistor are maintained with high precision, and the defective rate of the circuit board substrate is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of thick film circuit board production, and in particular to a printing process for thick film circuit boards.

Background Art

[0002] In the production process of thick film circuit boards, generally, it includes several steps such as printing, leveling, drying, and sintering. In the printing process, the commonly used and suitable process for large-scale manufacturing is the screen printing process. The first step of screen printing is to design a circuit pattern and make a screen containing an opening pattern according to the designed circuit pattern. Then, the pastes for conductors and electronic components, etc. are printed on the substrate through the screen printing process.

[0003] In the prior art, the basic method of forming a thick film on a substrate has been basically disclosed. For example, the prior art with the patent publication number DE68920783D1 discloses a method for forming a thick film on a substrate, including: sequentially forming thick films with a predetermined common pattern on a plurality of the substrates through screen printing; drying and sintering the plurality of substrates formed with the predetermined pattern; placing the substrates one by one on a movable table, wherein, based on the thick film pattern formed in the first step, controlling the movement of the table; and sequentially forming thick films with different patterns on each substrate by using direct writing, wherein the area of the substrate with the thick film formed by direct writing often has pattern changes.

[0004] In summary, the prior art has disclosed the basic steps of the printing process for thick film circuit boards, but has not mentioned the specific steps, pressure control, and gap control of the printing process for thick film circuit boards. Processing according to the method disclosed in the prior art can achieve the printing and subsequent processing of thick film circuit boards, but the printing thickness of the manufactured thick film circuit boards is not easy to master, resulting in large fluctuations in the values of electronic components (especially resistors) on the thick film circuit boards, and ultimately making it difficult to carry out the subsequent drying and sintering processes, and even increasing the defective rate of thick film circuit boards.

Summary of the Invention

[0005] In order to solve the technical problem that the thickness of thick film circuit boards and the values of electronic components in the prior art have large fluctuations, resulting in a high defective rate of thick film circuit boards, the present invention provides a printing process for thick film circuit boards.

[0006] The present invention provides a printing process for thick film circuit boards, including the following steps:

[0007] S01. Load the paste into a screen printing machine, and the mesh number range of the screen of the screen printing machine is from 400 meshes to 600 meshes;

[0008] S02. Adjust the position of the screen printing machine to align the position of the screen printing machine with that of the circuit board substrate.

[0009] S03. Adjust the gap between the circuit board substrate and the screen of the screen printing machine, where the range of the gap is from 200 μm to 400 μm.

[0010] S04. Adjust the pressure between the squeegee of the screen printing machine and the circuit board substrate, where the range of the pressure is from 200 N to 300 N.

[0011] S05. Adjust the movement length of the screen printing machine, where the difference between the movement length of the screen printing machine and the length of the circuit board substrate is greater than or equal to two inches.

[0012] S06. Adjust the movement direction of the squeegee so that the included angle between the movement direction of the squeegee and the length direction of the circuit board substrate ranges from 30° to 45°.

[0013] It should be noted that the mesh number range of the screen can be 400 mesh, 450 mesh, 500 mesh, 550 mesh, and 600 mesh.

[0014] It should be noted that the range of the gap can be 200 μm, 250 μm, 300 μm, 350 μm, and 400 μm.

[0015] It should be noted that the pressure value can be 200 N, 220 N, 240 N, 260 N, and 300 N.

[0016] It should be noted that the included angle can be 30°, 35°, 40°, 42°, and 45°.

[0017] Compared with the prior art, the printing process of the thick film circuit board provided by the present invention controls the mesh number of the screen of the screen printing machine, the gap between the circuit board substrate and the screen of the screen printing machine, the pressure between the squeegee of the screen printing machine and the circuit board substrate, the drying time of the circuit board substrate, and the range of the included angle between the movement direction of the squeegee and the length direction of the circuit board substrate in the printing process, so that the thickness of the circuit board substrate and the thickness of the resistor are maintained with high precision, and the defective rate of the circuit board substrate is reduced.

Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings, where:

[0019] Figure 1 is a flowchart of the printing process of the thick film circuit board provided by the present invention;

[0020] Figure 2 is as Figure 1 shown in the flowchart of step S02 in the printing process of the thick film circuit board;

[0021] Figure 3 is a statistical chart of the circuit board substrate and resistor dispersion of Embodiment 1 to Embodiment 5 of the present invention.

Specific Embodiments

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0023] Please refer to Figure 1 , a printing process for a thick film circuit board provided by the present invention includes:

[0024] S01. Load the paste into the screen printing machine, and the mesh number range of the screen of the screen printing machine is from 400 meshes to 600 meshes;

[0025] S02. Adjust the position of the screen printing machine to achieve the position correspondence between the screen printing machine and the circuit board substrate;

[0026] S03. Adjust the gap between the circuit board substrate and the screen of the screen printing machine, and the range of the gap is from 200 μm to 400 μm;

[0027] S04. Adjust the pressure between the squeegee of the screen printing machine and the circuit board substrate, and the range of the pressure is from 200 N to 300 N.

[0028] S05. Adjust the movement length of the screen printing machine, and the difference between the movement length of the screen printing machine and the length of the circuit board substrate is greater than or equal to two inches.

[0029] S06. Adjust the movement direction of the squeegee so that the included angle between the movement direction of the squeegee and the length direction of the circuit board substrate is in the range of 30° to 45°.

[0030] S07. Dry the circuit board substrate in a high-temperature environment, and the drying duration range is from 30 min to 60 min.

[0031] Please refer to Figure 2 ,Figure 2 is the flowchart of step S02 in the printing process of the thick film circuit board as Figure 1 shown.

[0032] The said step S02 includes:

[0033] S21. Cover the preparation tape on the circuit board substrate, and then operate the screen printing machine to print the circuit diagram on the preparation tape;

[0034] S22. Judge whether the positions of the screen printing machine and the circuit board substrate correspond;

[0035] S23. If there is a deviation in the positions of the screen printing machine and the circuit board substrate, perform position adjustment.

[0036] It should be noted that when the paste is palladium-silver conductor or platinum-silver conductor, the thickness range of the dried circuit board substrate is 28μm to 32μm.

[0037] It should be noted that when the paste is gold conductor, the thickness range of the dried circuit board substrate is 20μm to 22μm.

[0038] It should be noted that the circuit board substrate is provided with a resistor, and the thickness of the resistor is 35±3μm.

[0039] It should be noted that in step S07, the circuit board substrate is dried in a high-temperature environment, and the range of the high temperature in the high-temperature environment is 120 degrees Celsius to 140 degrees Celsius.

[0040] Embodiment 1

[0041] The printing process of the thick film circuit board in this embodiment includes the following steps:

[0042] S01. Load the paste into the screen printing machine, and the mesh number range of the screen of the screen printing machine is 400 meshes;

[0043] S02. Cover the preparation tape on the circuit board substrate, and then operate the screen printing machine to print the circuit diagram on the preparation tape; judge whether the positions of the screen printing machine and the circuit board substrate correspond; if there is a deviation in the positions of the screen printing machine and the circuit board substrate, perform position adjustment;

[0044] S03. Adjust the gap between the circuit board substrate and the screen of the screen printing machine, and the gap is 400μm;

[0045] S04. Adjust the pressure between the squeegee of the screen printing machine and the circuit board substrate, and the range of the pressure is 200N;

[0046] S05. Adjust the moving length of the screen printing machine, with the difference between the moving length of the screen printing machine and the length of the circuit board substrate being two inches.

[0047] S06. Adjust the moving direction of the squeegee so that the angle between the moving direction of the squeegee and the length direction of the circuit board substrate is 30°.

[0048] S07. Dry the circuit board substrate in a high-temperature environment, with the drying duration ranging from 60 minutes.

[0049] Measure the thickness of the dried circuit board substrate. During the measurement, select three measurement points at the upper left corner, the center (near the center), and the lower right corner of the circuit board substrate for measurement. The thickness changes of the circuit board substrate are 31.3 μm, 32 μm, and 30.1 μm, and the fluctuation range from the thickest to the thinnest is 1.9 μm.

[0050] Similarly, select three measurement points at the upper left corner, the center (near the center), and the lower right corner of the resistor for measurement. The thickness changes of the resistor are 33.4 μm, 38 μm, and 35.8 μm, and the fluctuation range from the thickest to the thinnest is 4.6 μm.

[0051] Example Two

[0052] The printing process of the thick film circuit board in this example includes the following steps:

[0053] S01. Load the paste into the screen printing machine, with the mesh number of the screen of the screen printing machine ranging from 450 meshes;

[0054] S02. Cover the circuit board substrate with a preparation tape, and then operate the screen printing machine to print the circuit diagram on the preparation tape; judge whether the positions of the screen printing machine and the circuit board substrate correspond; if there is a deviation in the positions of the screen printing machine and the circuit board substrate, perform position adjustment;

[0055] S03. Adjust the gap between the circuit board substrate and the screen of the screen printing machine, with the gap being 250 μm;

[0056] S04. Adjust the pressure between the squeegee of the screen printing machine and the circuit board substrate, with the pressure ranging from 220 N;

[0057] S05. Adjust the moving length of the screen printing machine, with the difference between the moving length of the screen printing machine and the length of the circuit board substrate being two inches.

[0058] S06. Adjust the moving direction of the squeegee so that the angle between the moving direction of the squeegee and the length direction of the circuit board substrate is 35°.

[0059] S07. Dry the circuit board substrate in a high-temperature environment, and the drying duration ranges from 60 min.

[0060] Measure the thickness of the dried circuit board substrate. During the measurement, select 3 measurement points at the upper left corner, the center (near the center) of the substrate, and the lower right corner of the circuit board substrate for measurement. The thickness changes of the circuit board substrate are 31.1 μm, 31.5 μm, and 30.3 μm, and the fluctuation range from the thickest to the thinnest is 1.2 μm.

[0061] Similarly, select 3 measurement points at the upper left corner, the center (near the center) of the resistor, and the lower right corner of the resistor for measurement. The thickness changes of the resistor are 32.7 μm, 36.9 μm, and 34.8 μm, and the fluctuation range from the thickest to the thinnest is 4.2 μm.

[0062] Example 3

[0063] The printing process of the thick-film circuit board in this example includes the following steps:

[0064] S01. Load the paste into the screen printer, and the mesh number of the screen of the screen printer ranges from 500 meshes;

[0065] S02. Cover the preparation tape on the circuit board substrate, and then operate the screen printer to print the circuit diagram on the preparation tape; judge whether the positions of the screen printer and the circuit board substrate correspond; if there is a deviation in the positions of the screen printer and the circuit board substrate, perform position adjustment;

[0066] S03. Adjust the gap between the circuit board substrate and the screen of the screen printer, and the gap is 300 μm;

[0067] S04. Adjust the pressure between the squeegee of the screen printer and the circuit board substrate, and the pressure range is 240 N;

[0068] S05. Adjust the movement length of the screen printer, and the difference between the movement length of the screen printer and the length of the circuit board substrate is two inches.

[0069] S06. Adjust the movement direction of the squeegee so that the included angle between the movement direction of the squeegee and the length direction of the circuit board substrate is 40°.

[0070] S07. Dry the circuit board substrate in a high-temperature environment, and the drying duration ranges from 60 min.

[0071] Measure the thickness of the dried circuit board substrate. During the measurement process, select three measurement points at the upper left corner, the center of the substrate (near the center), and the lower right corner of the circuit board substrate for measurement. The thickness variations of the circuit board substrate are 30.2μm, 30.5μm, and 29.7μm, and the fluctuation range from the thickest to the thinnest is 0.8μm.

[0072] Similarly, select three measurement points at the upper left corner, the center of the resistor (near the center), and the lower right corner of the resistor for measurement. The thickness variations of the resistor are 32.3μm, 35.8μm, and 33.5μm, and the fluctuation range from the thickest to the thinnest is 3.5μm.

[0073] Example 4

[0074] The printing process of the thick film circuit board in this example includes the following steps:

[0075] S01. Load the paste into the screen printing machine, and the mesh number range of the screen of the screen printing machine is 550 meshes;

[0076] S02. Cover the preparation tape on the circuit board substrate, and then operate the screen printing machine to print the circuit diagram on the preparation tape; judge whether the positions of the screen printing machine and the circuit board substrate correspond; if there is a deviation in the positions of the screen printing machine and the circuit board substrate, perform position adjustment;

[0077] S03. Adjust the gap between the circuit board substrate and the screen of the screen printing machine, and the gap is 350μm;

[0078] S04. Adjust the pressure between the squeegee of the screen printing machine and the circuit board substrate, and the pressure range is 260N;

[0079] S05. Adjust the movement length of the screen printing machine, and the difference between the movement length of the screen printing machine and the length of the circuit board substrate is two inches.

[0080] S06. Adjust the movement direction of the squeegee so that the included angle between the movement direction of the squeegee and the length direction of the circuit board substrate is 42°;

[0081] S07. Dry the circuit board substrate in a high-temperature environment, and the drying duration range is 60min.

[0082] Measure the thickness of the dried circuit board substrate. During the measurement process, select three measurement points at the upper left corner, the center of the substrate (near the center), and the lower right corner of the circuit board substrate for measurement. The thickness variations of the circuit board substrate are 29.7μm, 30.1μm, and 29.6μm, and the fluctuation range from the thickest to the thinnest is 0.5μm.

[0083] Similarly, three measurement points at the upper left corner, the center (near the center), and the lower right corner of the resistor are selected for measurement. The thickness variations of the resistor are 32.1μm, 33.1μm, and 32.4μm, and the fluctuation range from the thickest to the thinnest is 1μm.

[0084] Example Five

[0085] The printing process of the thick film circuit board in this example includes the following steps:

[0086] S01. Load the paste into the screen printing machine, and the mesh number range of the screen of the screen printing machine is 600 meshes;

[0087] S02. Cover the preparation tape on the circuit board substrate, and then operate the screen printing machine to print the circuit diagram on the preparation tape; judge whether the positions of the screen printing machine and the circuit board substrate correspond; if there is a deviation in the positions of the screen printing machine and the circuit board substrate, perform position adjustment;

[0088] S03. Adjust the gap between the circuit board substrate and the screen of the screen printing machine, and the gap is 400μm;

[0089] S04. Adjust the pressure between the squeegee of the screen printing machine and the circuit board substrate, and the pressure range is 300N;

[0090] S05. Adjust the movement length of the screen printing machine, and the difference between the movement length of the screen printing machine and the length of the circuit board substrate is two inches.

[0091] S06. Adjust the movement direction of the squeegee so that the included angle between the movement direction of the squeegee and the length direction of the circuit board substrate is 45°;

[0092] S07. Dry the circuit board substrate in a high-temperature environment, and the drying duration range is 60min.

[0093] Measure the thickness of the dried circuit board substrate. During the measurement process, three measurement points at the upper left corner, the center (near the center), and the lower right corner of the circuit board substrate are selected for measurement. The thickness variations of the circuit board substrate are 28μm, 29.1μm, and 28.6μm, and the fluctuation range from the thickest to the thinnest is 1.1μm.

[0094] Similarly, three measurement points at the upper left corner, the center (near the center), and the lower right corner of the resistor are selected for measurement. The thickness variations of the resistor are 32μm, 34.2μm, and 33.4μm, and the fluctuation range from the thickest to the thinnest is 2.2μm.

[0095] After a large amount of experimental data statistics, a summary of the dimensional fluctuations of the thickness of the circuit board substrate and the resistor after printing and drying in the above embodiments is shown in Table 1 and Figure 3 as shown, where Table 1 is the statistical result of the air bubbles in the conductor after printing and sintering of the thick film circuit gold conductor paste, Figure 3 and it is the statistical chart of the dispersion of the circuit board substrate and the resistor from Embodiment 1 to Embodiment 5 of the present invention.

[0096] Table 1

[0097] It can be seen from the drawings and Table 1 that the printing process of the thick film circuit board provided by the present invention improves the accuracy of the thickness of the surface of the printed thick film circuit board and the thickness of the resistor by controlling the mesh number of the screen of the screen printing machine, the gap size between the circuit board substrate and the screen of the screen printing machine, the pressure size between the squeegee of the screen printing machine and the circuit board substrate, and the included angle size between the moving direction of the squeegee and the length direction of the circuit board substrate, resulting in a smaller dispersion of the thick film circuit board substrate and the resistor, and further indicating its better stability. Especially under the conditions of Embodiment 4 of the present invention, the highest thickness accuracy of the thick film circuit board substrate and the resistor is obtained.

[0098] The above are only the embodiments of the present invention. It should be noted here that for those of ordinary skill in the art, improvements can be made without departing from the inventive concept of the present invention, but these all belong to the protection scope of the present invention.

Claims

1. A printing process for a thick film circuit board, characterized in that, It includes the following steps: S01. Load the paste into a screen printing machine, where the mesh number of the screen of the screen printing machine ranges from 400 meshes to 600 meshes; S02. Adjust the position of the screen printing machine to make the positions of the screen printing machine and the circuit board substrate correspond; S03. Adjust the gap between the circuit board substrate and the screen of the screen printing machine, and the range of the gap is from 200 μm to 400 μm; S04. Adjust the pressure between the squeegee of the screen printing machine and the circuit board substrate, and the range of the pressure is from 200 N to 300 N; S05. Adjust the moving length of the screen printing machine, and the difference between the moving length of the screen printing machine and the length of the circuit board substrate is greater than or equal to two inches; S06. Adjust the moving direction of the squeegee so that the included angle between the moving direction of the squeegee and the length direction of the circuit board substrate ranges from 30° to 42°; S07. Dry the circuit board substrate in a high-temperature environment, and the drying duration ranges from 30 min to 60 min; When the paste is a palladium-silver conductor or a platinum-silver conductor, the thickness of the dried circuit board substrate ranges from 28 μm to 32 μm; The circuit board substrate is provided with a resistor, and the thickness of the resistor is 35 ± 3 μm.

2. The printing process of the thick film circuit board according to claim 1, characterized in that, The step S02 includes: S21. Cover a preparation tape on the circuit board substrate, and then operate the screen printing machine to print the circuit diagram on the preparation tape; S22. Judge whether the positions of the screen printing machine and the circuit board substrate correspond; S23. If there is a deviation in the positions of the screen printing machine and the circuit board substrate, perform position adjustment.

3. The printing process of the thick film circuit board according to claim 1, characterized in that, When the paste is a gold conductor, the thickness of the dried circuit board substrate ranges from 20 μm to 22 μm.

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