Manufacturing method of high-speed signal optical module board

Abstract

The invention provides a manufacturing method of a high-speed signal optical module board. The manufacturing method comprises the following steps: S1, cutting; s2, performing inner layer line exposure by using LDI, and performing vacuum etching; s3, laminating: adjusting the flatness of a press before laminating the optical module board; the heating rate of the press is adjusted; then laminating a calendered module board; after lamination is completed, a thickness gauge is used for plate thickness detection; s4, drilling and copper deposition; s5, whole plate electroplating is conducted, specifically, a two-time whole plate electroplating mode is adopted, the current densities of the two times are completely the same, clamping plate electroplating is conducted in one direction in the first time, and clamping plate electroplating is conducted by rotating 180 degrees in the second time; s6, an outer layer circuit; s7, resistance welding and character processing; s8, appearance milling: milling the appearance by using an optical CCD milling machine; and S9, inspecting a finished product. The technical scheme has the beneficial effects that the plate thickness, the line width, the copper thickness and the appearance of the optical module plate are controlled by controlling online manufacturing factors, so that the stability of an optical module plate product is ensured, and the yield is improved.

Description

Technical Field

[0001] The invention relates to the technical field of circuit board manufacturing, and in particular to a method for manufacturing a high-speed signal optical module board. Background Art

[0002] With the popularization of 5G and the wide application of ports, the demand for optical modules is increasing. Optical modules are electronic devices that perform photoelectric conversion, and printed circuit boards (PCBs) play a key role as part of optical modules. However, the printed circuit boards of optical modules currently use the same manufacturing method as general printed circuit boards. The resulting printed circuit boards generally have problems such as low pass rate and poor stability, and signal transmission anomalies cause optical modules to fail. Optical module boards, that is, printed circuit boards of optical modules, require much higher consistency and stability of signal transmission than general printed circuit boards due to the need to transmit high-speed signals. If the board thickness, line width, copper thickness, and shape fluctuate greatly, signal transmission anomalies will occur, leading to failure. Therefore, in the process of manufacturing optical module boards for transmitting high-speed signals, it is necessary to control the board thickness, line width, copper thickness, and shape of the optical module boards. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for manufacturing a high-speed signal optical module board.

[0004] The present invention is achieved in that:

[0005] A method for manufacturing a high-speed signal optical module board comprises the following steps:

[0006] S1, cutting;

[0007] S2, inner layer circuit: use LDI exposure and vacuum etching, and the circuit etching line width tolerance is controlled at + / -10%;

[0008] S3, lamination: before laminating the optical module board, adjust the flatness of the press to within + / -0.05MM; adjust the heating rate of the press to control the heating rate at 2.5-3.5℃ / MIN; then laminate the optical module board; after lamination, use a thickness gauge to detect the board thickness, and the board thickness tolerance is controlled within + / -0.05MM;

[0009] S4, drilling and copper sinking;

[0010] S5, whole board electroplating: two whole board electroplatings are adopted, and the current density of the two times is exactly the same. The first time, the plate is fixed in one direction for electroplating, and the second time, the plate is rotated 180 degrees for electroplating. The copper thickness tolerance is controlled within 3UM;

[0011] S6, outer circuit;

[0012] S7, solder mask and characters;

[0013] S8. Shape: Use optical CCD milling machine to mill the shape, and the shape tolerance is controlled within + / -0.075MM. After milling, use full-size measuring instrument to detect the shape size;

[0014] S9. Finished product inspection.

[0015] Furthermore, the material cutting is specifically as follows: using low-loss high-speed board material, the dielectric constant DK is 3.7, the dielectric loss factor Df is 0.005, and the core board thickness is 0.2MM.

[0016] Furthermore, between the inner layer circuit and the lamination, S2-1, inner layer AOI test is also included.

[0017] Furthermore, the outer circuit is specifically:

[0018] S6-1, the first outer layer circuit: use LDI exposure machine to expose, use conventional dry film to make the circuit, and connect the gold finger with the copper foil inside the board;

[0019] S6-2, film stripping and etching: vacuum etching is used, and the line width tolerance of circuit etching is controlled at + / -10%;

[0020] S6-3, outer layer AOI test;

[0021] S6-4, Impedance test: Impedance tolerance is controlled at + / -8%;

[0022] S6-5, Second outer layer circuit: Use electroplating resistant dry film to cover all circuits and only keep the gold finger pattern;

[0023] S6-6, Plug gold plating: Electroplating hard gold, gold fingers cannot have leads;

[0024] S6-7, film removal: remove the dry film to reveal the gold finger guide pattern;

[0025] S6-8, the third outer layer circuit: cover all the patterns and only keep the lead part inside the board;

[0026] S6-9, Etching and stripping: Etching the lead part inside the board.

[0027] Furthermore, the finished product inspection is specifically as follows:

[0028] S9-1, electrical measurement;

[0029] S9-2, sunken silver;

[0030] S9-3, FQC;

[0031] S9-4. Packaging.

[0032] Compared with the background technology, the technical solution of the present invention has the following beneficial effects:

[0033] 1. By controlling online manufacturing factors, adjusting the heating rate and the flatness of the press in the lamination process to control the board thickness, using the whole board electroplating and two rotation electroplating methods in the electroplating process to improve the uniformity of copper thickness, using vacuum etching during etching to improve the uniformity of line width, and using CCD milling machines instead of ordinary milling machines in the contour process to control the contour tolerance. The above methods can ensure the stability of optical module board products and improve the yield.

[0034] 2. Through the three-time exposure method of the outer layer circuit, the lead in the gold finger area is replaced by the inner lead of the board to realize the lead-free electroplated gold finger, which improves the consistency and stability of the optical module board in high-speed signal transmission and is widely used in servers and data processors. DETAILED DESCRIPTION

[0035] The embodiment of the present invention provides a method for manufacturing a high-speed signal optical module board, which overcomes the problem that the printed circuit board of the current optical module in the background technology adopts the same manufacturing method as the general printed circuit board, and the resulting printed circuit board generally has the problems of low qualified rate, poor stability, and abnormal signal transmission leading to optical module failure; and achieves the technical effect of ensuring the stability of the optical module board product and improving the yield.

[0036] The overall idea of ​​the technical solution of the embodiment of the present invention is as follows:

[0037] By controlling online manufacturing factors, the heating rate and the flatness of the press are adjusted in the lamination process to control the board thickness, the whole board electroplating and two rotation electroplating methods are used in the electroplating process to improve the uniformity of copper thickness, vacuum etching is used during etching to improve the uniformity of line width, and CCD milling machines are used instead of ordinary milling machines to control the shape tolerance in the contour process.

[0038] The key manufacturing factors of the optical module board are controlled as follows:

[0039] (1) Plate thickness tolerance, especially the plate thickness tolerance of the gold finger area is controlled within + / -0.05MM;

[0040] (2) The shape tolerance, especially the shape tolerance of the gold finger area, is controlled within + / -0.075MM;

[0041] (3) Line width tolerance: vacuum etching is used and the line width tolerance is controlled within + / -10%;

[0042] (4) Copper thickness tolerance: The whole board is electroplated and the copper thickness tolerance is controlled within 3UM.

[0043] In order to better understand the above technical solution, the following specific implementation method will describe the above technical solution in detail.

[0044] A method for manufacturing a high-speed signal optical module board comprises the following steps:

[0045] S1. Cutting: Use low-loss high-speed board, dielectric constant DK is 3.7, dielectric loss factor Df is 0.005, core board thickness is 0.2MM. Six-layer board.

[0046] S2, inner layer circuit: use LDI exposure and vacuum etching, the circuit etching line width tolerance is controlled at + / -10% to improve the circuit yield.

[0047] S2-1. Inner layer AOI test: There should be no gaps or residual copper in the circuit.

[0048] S3, lamination: before laminating the optical module board, adjust the flatness of the press to within + / -0.05MM; adjust the heating rate of the press to control the heating rate at 2.5-3.5℃ / MIN; then laminate the optical module board; after lamination, use a thickness gauge to detect the board thickness, and the board thickness tolerance is controlled within + / -0.05MM.

[0049] S4, drilling and copper plating: plasma treatment is required after drilling.

[0050] S5, whole board electroplating: adopt the form of two whole board electroplating, the current density of the two times is exactly the same, the first time is fixed in one direction of the clamping plate electroplating, the second time is rotated 180 degrees for electroplating, the copper thickness tolerance is controlled within 3UM; reducing the difference in copper thickness between high and low potentials can improve the uniformity of electroplated copper thickness. In comparison, the copper thickness tolerance of the pattern electroplating used in ordinary printed circuit boards is generally more than 5UM.

[0051] S6, outer circuit; specifically:

[0052] S6-1, the first outer layer circuit: use LDI exposure machine to expose, use conventional dry film to make the circuit, and connect the gold finger with the copper foil inside the board;

[0053] S6-2, film stripping and etching: vacuum etching is used, and the line width tolerance of circuit etching is controlled at + / -10%;

[0054] S6-3, outer layer AOI test;

[0055] S6-4, Impedance test: Impedance tolerance is controlled at + / -8%;

[0056] S6-5, Second outer layer circuit: Use electroplating resistant dry film to cover all circuits and only keep the gold finger pattern;

[0057] S6-6, Plug gold plating: Electroplating hard gold, gold fingers cannot have leads;

[0058] S6-7, film removal: remove the dry film to reveal the gold finger guide pattern;

[0059] S6-8, the third outer layer circuit: cover all the patterns and only keep the lead part inside the board;

[0060] S6-9, Etching and stripping: Etching the lead part inside the board.

[0061] S7, solder mask and characters; in the solder mask process, control the yield rate, some high-speed boards cannot be reworked; in the character process, carry out normal production.

[0062] S8. Shape: Use optical CCD milling machine to mill the shape, and the shape tolerance is controlled within + / -0.075MM. After milling, use full-size measuring instrument to detect the shape size;

[0063] S9. Finished product inspection, specifically:

[0064] S9-1, electrical testing; the line cannot be repaired.

[0065] S9-2, immersion silver; normal production.

[0066] S9-3, FQC; Comprehensively inspect the appearance and performance of the optical module board.

[0067] S9-4. Packaging.

[0068] Beneficial effects of the technical solution of the present invention:

[0069] 1. By controlling online manufacturing factors, adjusting the heating rate and the flatness of the press in the lamination process to control the board thickness, using the whole board electroplating and two rotation electroplating methods in the electroplating process to improve the uniformity of copper thickness, using vacuum etching during etching to improve the uniformity of line width, and using CCD milling machines instead of ordinary milling machines in the contour process to control the contour tolerance. The above methods can ensure the stability of optical module board products and improve the yield.

[0070] 2. Through the three-time exposure method of the outer layer circuit, the lead in the gold finger area is replaced by the inner lead of the board to realize the lead-free electroplated gold finger, which improves the consistency and stability of the optical module board in high-speed signal transmission and is widely used in servers and data processors.

[0071] Although the specific implementation modes of the present invention are described above, those skilled in the art should understand that the specific implementation modes described are only illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for manufacturing a high-speed signal optical module board, characterized in that: The following steps are involved: S1, cutting; S2, inner layer circuit: use LDI exposure and vacuum etching, and the circuit etching line width tolerance is controlled at + / -10%; S3, lamination: before laminating the optical module board, adjust the flatness of the press to within + / -0.05MM; adjust the heating rate of the press to control the heating rate at 2.5-3.5℃ / MIN; then laminate the optical module board; after lamination, use a thickness gauge to detect the board thickness, and the board thickness tolerance is controlled within + / -0.05MM; S4, drilling and copper sinking; S5, whole board electroplating: two whole board electroplatings are adopted, and the current density of the two times is exactly the same. The first time, the plate is fixed in one direction for electroplating, and the second time, the plate is rotated 180 degrees for electroplating. The copper thickness tolerance is controlled within 3UM; S6, outer circuit; S7, solder mask and characters; S8. Shape: Use optical CCD milling machine to mill the shape, and the shape tolerance is controlled within + / -0.075MM. After milling, use full-size measuring instrument to detect the shape size; S9. Finished product inspection.

2. The method for manufacturing a high-speed signal optical module board according to claim 1, characterized in that: The cutting process is specifically as follows: using low-loss high-speed board material, the dielectric constant DK is 3.7, the dielectric loss factor Df is 0.005, and the core board thickness is 0.2MM.

3. The method for manufacturing a high-speed signal optical module board according to claim 1, characterized in that: Between the inner layer circuit and the lamination, it also includes S2-1, inner layer AOI test.

4. The method for manufacturing a high-speed signal optical module board according to claim 1, characterized in that: The outer circuit is specifically: S6-1, the first outer layer circuit: use LDI exposure machine to expose, use conventional dry film to make the circuit, and connect the gold finger with the copper foil inside the board; S6-2, film stripping and etching: vacuum etching is used, and the line width tolerance of circuit etching is controlled at + / -10%; S6-3, outer layer AOI test; S6-4, Impedance test: Impedance tolerance is controlled at + / -8%; S6-5, Second outer layer circuit: Use electroplating resistant dry film to cover all circuits and only keep the gold finger pattern; S6-6, Plug gold plating: Electroplating hard gold, gold fingers cannot have leads; S6-7, film removal: remove the dry film to reveal the gold finger guide pattern; S6-8, the third outer layer circuit: cover all the patterns and only keep the lead part inside the board; S6-9, Etching and stripping: Etching the lead part inside the board.

5. The method for manufacturing a high-speed signal optical module board according to claim 1, characterized in that: The finished product inspection is specifically as follows: S9-1, electrical measurement; S9-2, sunken silver; S9-3, FQC; S9-4. Packaging.