Manufacturing method of optical module circuit board and optical module circuit board

Abstract

The invention discloses a manufacturing method of an optical module circuit board and the optical module circuit board, and the manufacturing method of the optical module circuit board comprises the following steps: drilling: drilling through holes for the connection between layers on a PCB (Printed Circuit Board); copper deposition: carrying out oxidation-reduction reaction on the drilled circuit board, and forming a copper layer on the hole wall so as to metallize the through hole; manufacturing an outer-layer circuit, and manufacturing an outer-layer circuit pattern of the circuit board by adopting a negative film process; and manufacturing a metalized half hole, namely manufacturing the metalized half hole of the circuit board by adopting a positive film process. In the optical module circuit board with the half hole, the metalized half hole and the optical module circuit pattern are respectively manufactured by adopting a positive film process and a negative film process, so that the process requirements of the metalized half hole and the optical module circuit pattern are respectively met, and the problem that the metalized half hole is etched to be copper-free by acid etching in the negative film process is avoided; and the requirement of an optical module product on the wire top can be ensured in alkaline etching of a positive film process.

Description

Technical Field

[0001] The present invention relates to the technical field of manufacturing process of circuit boards, and in particular to a manufacturing method of an optical module circuit board and the optical module circuit board. Background Art

[0002] With the development of communication technology, optoelectronic module products are developing towards miniaturization, low power consumption, high speed and long distance. With this development trend, more and more optical module products require the design of half-hole on the edge of the circuit board.

[0003] In optical module products, the production of optical module circuit patterns on circuit boards generally adopts negative film technology, while metallized half holes generally adopt positive film technology. However, during the production process, the negative film technology often cannot guarantee the production requirements of the metal half holes, and the positive film technology cannot guarantee the production of optical module circuit patterns, which leads to serious quality problems in optical module products. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for manufacturing an optical module circuit board, which can ensure the product requirements of the metallized half holes on the circuit board and the optical module circuit pattern while manufacturing the circuit board of the optical module product.

[0005] The present invention also provides an optical module circuit board manufactured by adopting the manufacturing method of the optical module circuit board.

[0006] According to the method for manufacturing an optical module circuit board of the first aspect of the present invention, the method for manufacturing the optical module circuit board comprises the following steps:

[0007] Drilling: drilling through holes on the circuit board to connect the layers;

[0008] Copper deposition, an oxidation-reduction reaction is carried out on the circuit board after drilling to form a copper layer on the hole wall to metallize the through hole;

[0009] Make the outer layer circuit, use negative film process to make the outer layer circuit pattern of the circuit board; and

[0010] Make metallized half holes and use positive film process to make metallized half holes of circuit boards.

[0011] The method for manufacturing an optical module circuit board according to an embodiment of the present invention has at least the following beneficial effects: in an optical module circuit board with half holes, a positive film process and a negative film process are used to respectively manufacture the metallized half holes and the optical module circuit patterns, thereby meeting the process requirements of the metallized half holes and the optical module circuit patterns respectively, avoiding the problem of etching the metallized half holes into copper-free areas by acid etching in the negative film process, and ensuring that the requirements of the optical module product for the line top are met in the alkaline etching of the positive film process.

[0012] According to some embodiments of the present invention, the step of making the outer layer circuit further comprises the following steps:

[0013] One-time external light imaging, using dry film as a carrier in the circuit process, and exposing the circuit pattern required for the outer layer of the circuit board on the dry film through pattern transfer;

[0014] Acid etching, after removing the unexposed dry film, expose the outer copper surface, use acid etching solution to etch the copper surface to obtain the required circuit pattern.

[0015] According to some embodiments of the present invention, the one-time external light imaging step further comprises the following steps:

[0016] Lamination: placing the dry film on top of the circuit board and laminating it with a laminator;

[0017] Exposure: placing the laminated circuit board in the exposure area of ​​the exposure equipment, and adjusting the exposure time and light intensity to make the photosensitive material on the dry film react chemically under the action of ultraviolet light; and

[0018] Development: Place the exposed circuit board into the developer to remove the dry film on the unexposed part through chemical action.

[0019] According to some embodiments of the present invention, the step of making a metallized half hole comprises the following steps:

[0020] Secondary external light imaging, using dry film as a carrier in the circuit process, exposing the position of the metallized half hole on the dry film through pattern transfer;

[0021] Copper-tin plating: electroplating copper and tin on the circuit board to increase the thickness of the copper layer and provide corrosion protection;

[0022] Milling the intersecting grooves, using a milling cutter to mill the intersecting grooves at the locations of the metallized holes of the circuit board, and processing the required metallized half holes; and

[0023] Alkaline etching: The circuit board after milling the intersecting grooves is subjected to alkaline etching to remove the unnecessary copper layer and obtain the required metallized half-hole.

[0024] According to some embodiments of the present invention, the copper-tin plating step comprises the following steps:

[0025] Pre-treatment: Before the copper-tin plating step, the circuit board is cleaned to remove impurities on the surface;

[0026] Activation treatment: before the copper-tin plating step, the circuit board is activated to enhance the bonding strength between layers;

[0027] Copper plating: the cleaned and activated circuit board is placed in a copper plating tank, and the copper ions are reduced to copper atoms and deposited on the surface of the circuit board through the action of electric current; and

[0028] Tin plating: After copper plating is completed, the circuit board is placed in a tin plating tank for tin plating.

[0029] According to some embodiments of the present invention, the step of making the outer layer circuit further includes the following steps:

[0030] An outer layer etching inspection is to check and test the etching results after the outer layer etching process of the circuit board is completed.

[0031] According to some embodiments of the present invention, the step of making the metallized half hole further includes the following steps:

[0032] Secondary outer layer etching inspection: After the metallization half-hole etching process of the circuit board is completed, the etching results are inspected and tested.

[0033] According to the optical module circuit board of the embodiment of the second aspect of the present invention, the optical module circuit board is manufactured by using the manufacturing method of the optical module circuit board described in any one of the embodiments of the first aspect.

[0034] The optical module circuit board according to the embodiment of the present invention has at least the following beneficial effects: the optical module circuit board manufactured by the method for manufacturing the optical module circuit board described in any one of the embodiments of the first aspect can reduce the occurrence of problems such as etching the metallized half-hole into copper-free by acid etching in the negative film process and the failure to ensure the requirements of the optical module product for the line top in the alkaline etching in the positive film process, so that the optical module circuit board can have higher quality and thus reduce costs.

[0035] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0037] Figure 1 The figure is a flow chart of a method for manufacturing an optical module circuit board according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0039] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0040] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0041] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0042] Reference Figure 1 According to the method for manufacturing an optical module circuit board of the first aspect of the present invention, the method for manufacturing the optical module circuit board comprises the following steps:

[0043] Step S100: drilling holes, drilling through holes on the PCB board for connecting layers;

[0044] Step S200: copper deposition, an oxidation-reduction reaction is performed on the circuit board after drilling to form a copper layer on the hole wall to metallize the through hole;

[0045] Step S300: making outer layer circuits, using negative film process to make outer layer circuit patterns of the circuit board;

[0046] Step S400: making metallized half holes, using a positive film process to make metallized half holes of a circuit board.

[0047] Specifically, first in step S100, a PCB substrate that meets the requirements is selected, and the substrate can be FR-4 (glass fiber reinforced epoxy resin) or other materials suitable for high-speed signal transmission. A precision CNC drilling machine is used to drill through holes for connecting layers on the PCB board. These through holes are used for subsequent electrical connections and signal transmission, so their position and dimensional accuracy must be strictly controlled. The hole wall must be kept smooth during the drilling process to reduce the difficulty of subsequent metallization processing.

[0048] After the drilling is completed, step S200 is then performed: copper plating is performed on the circuit board. This step involves an oxidation-reduction reaction to form a uniform copper layer on the hole wall. The specific operation is: first immerse the circuit board in a chemical solution containing copper ions, and then apply an electric current to cause the copper ions to be reduced to copper on the hole wall, thereby achieving metallization of the hole wall. The thickness of the copper plating layer needs to be moderate, both to ensure good conductivity and to avoid waste of resources and subsequent processing difficulties caused by excessive thickening.

[0049] Next, in step S300, the outer circuit pattern of the circuit board is made by a negative film process. The negative film process refers to forming the desired circuit pattern on a copper layer covered with photoresist by photolithography technology. The specific operation includes: firstly, a layer of photoresist is coated on the surface of the circuit board, and then a photolithography machine is used to expose the designed circuit pattern to the photoresist. The photoresist of the unexposed part is removed during the development process, leaving a bare copper layer corresponding to the circuit pattern. Subsequently, the exposed copper layer is removed by an etching solution, leaving the copper layer protected by the photoresist as the outer layer circuit. This step needs to ensure the accuracy and integrity of the circuit pattern to meet the high performance requirements of the optical module.

[0050] Finally, step S400 uses a positive film process to make the metallized half hole of the circuit board. The positive film process is similar to the negative film process, but its exposure and etching steps are opposite, and it is suitable for forming a specific metallized structure. In this step, first, a photoresist is applied to the other side of the circuit board (or the area where the metallized half hole needs to be made), and an opening at the position of the half hole is formed by photolithography. Subsequently, copper or other conductive materials are deposited at these openings by electroplating technology to form a metallized half hole. The production of the metallized half hole is crucial for realizing interlayer interconnection, improving signal transmission efficiency, and enhancing the mechanical strength of the circuit board.

[0051] Therefore, it can be understood that the method for manufacturing an optical module circuit board according to an embodiment of the present invention has at least the following beneficial effects: in an optical module circuit board with half holes, a positive film process and a negative film process are used to respectively manufacture the metallized half holes and the optical module circuit patterns, thereby meeting the process requirements of the metallized half holes and the optical module circuit patterns respectively, avoiding the problem of etching the metallized half holes into copper-free areas by acid etching in the negative film process, and ensuring that the requirements of the optical module product for the line top are met in the alkaline etching of the positive film process.

[0052] In some embodiments of the present invention, the step of making the outer layer circuit further comprises the following steps:

[0053] One-time external light imaging, using dry film as a carrier in the circuit process, and exposing the circuit pattern required for the outer layer of the circuit board on the dry film through pattern transfer;

[0054] Acid etching, after removing the unexposed dry film, expose the outer copper surface, use acid etching solution to etch the copper surface to obtain the required circuit pattern.

[0055] Furthermore, in some embodiments of the present invention, an external light imaging step further includes the following steps:

[0056] Lamination: placing the dry film on top of the circuit board and laminating it with a laminator;

[0057] Exposure: Place the laminated circuit board in the exposure area of ​​the exposure equipment, and adjust the exposure time and light intensity to make the photosensitive material on the dry film react chemically under the action of ultraviolet light;

[0058] Development: Place the exposed circuit board into the developer to remove the dry film on the unexposed part through chemical action.

[0059] So specifically, step S300 also includes the following steps: First, the selected dry film is attached to the surface of the PCB board that has completed the copper plating process. The selection of the dry film needs to be determined according to the required circuit accuracy, etching resistance and subsequent processing requirements. Then, a high-precision exposure device, such as an ultraviolet light exposure machine, is used to transfer the designed outer layer circuit pattern to the dry film. In this process, the photosensitive material on the dry film undergoes a chemical reaction under the action of ultraviolet light to form a latent image corresponding to the circuit pattern. Then, after exposure, the PCB board is placed in a developer, and the unexposed dry film part is dissolved and removed, while the exposed part is retained to form a clear circuit pattern. The development process requires strict control of the temperature, concentration and development time of the developer to ensure the accuracy and integrity of the circuit pattern.

[0060] After completing an external light imaging, the next step is an acid etching step to remove the unexposed copper layer and form the required outer layer circuit pattern. The specific operation is as follows: First, use an appropriate chemical solution or mechanical method to remove the unexposed dry film remaining on the surface of the PCB board to expose the outer copper surface. Then, put the PCB board with the exposed copper surface into an acid etching solution. The acidic substance in the etching solution reacts chemically with the copper to remove the copper layer not protected by the dry film. During the etching process, the fluidity and temperature of the etching solution must be kept stable to ensure the uniformity and depth control of the etching. After the etching is completed, use clean water or a special cleaning agent to thoroughly clean the PCB board to remove the residual etching solution and impurities. Finally, put the PCB board into an oven for drying to remove moisture and prepare for subsequent processing steps.

[0061] In some embodiments of the present invention, the step of making a metallized half hole comprises the following steps:

[0062] Secondary external light imaging, using dry film as a carrier in the circuit process, exposing the position of the metallized half hole on the dry film through pattern transfer;

[0063] Copper-tin plating: electroplating copper and tin on the circuit board to increase the thickness of the copper layer and provide corrosion protection;

[0064] Milling intersecting grooves: Use a milling cutter to mill intersecting grooves at the locations of the metallized holes on the circuit board to produce the required metallized half holes;

[0065] Alkaline etching: The circuit board after milling the intersecting grooves is subjected to alkaline etching to remove the unnecessary copper layer and obtain the required metallized half-hole.

[0066] Further, in some embodiments of the present invention, the step of copper-tin plating includes the following steps:

[0067] Pre-treatment: Before the copper-tin plating step, the circuit board is cleaned to remove impurities on the surface;

[0068] Activation treatment: before the copper-tin plating step, the circuit board is activated to enhance the bonding strength between layers;

[0069] Copper plating: put the cleaned and activated circuit board into the copper plating tank, and the copper ions are reduced to copper atoms and deposited on the surface of the circuit board through the action of electric current;

[0070] Tin plating: After copper plating is completed, the circuit board is placed in a tin plating tank for tin plating.

[0071] Specifically, in the second external light imaging step, the dry film is used again as a carrier in the circuit process, and the position of the metallized half hole is exposed on the dry film through pattern transfer. The specific operation is similar to the first external light imaging, but the purpose of this time is to locate the position of the metallized half hole.

[0072] First, the dry film is attached to the surface of the circuit board with the outer layer circuit made, ensuring that the dry film fits tightly to the surface of the circuit board without bubbles or wrinkles. Then, a high-precision exposure device is used to transfer the designed metallized half-hole pattern to the dry film. By adjusting the exposure time and light source intensity, the photosensitive material on the dry film undergoes a chemical reaction under the action of ultraviolet light to form a latent image corresponding to the metallized half-hole pattern. Next, the exposed circuit board is placed in a developer to remove the unexposed part of the dry film through chemical action, retaining the exposed part of the dry film, thereby forming a clear metallized half-hole pattern on the surface of the circuit board.

[0073] After completing the secondary external light imaging, the copper-tin plating step begins. It is necessary to electroplate copper and tin on the circuit board to increase the thickness of the copper layer and provide corrosion protection. Specifically, it includes: pre-treatment of the circuit board, including cleaning, degreasing, activation and other steps to ensure a good electroplating effect. The circuit board is placed in the copper electroplating solution, and a uniform copper layer is plated on the surface of the circuit board by electrolysis. The thickness and uniformity of the electroplated copper need to be strictly controlled to ensure the needs of subsequent processing and use. After the copper electroplating is completed, the circuit board is placed in the tin electroplating solution, and a layer of tin is plated on the surface of the copper layer by electrolysis. The tin layer has good corrosion resistance and solderability, can protect the copper layer from corrosion, and facilitate subsequent welding operations.

[0074] After the copper-tin plating is completed, in the step of milling the intersecting grooves, a milling cutter is needed to mill out the intersecting grooves at the locations of the metallized holes of the circuit board, thereby processing the required metallized half holes. The specific steps include: accurately locating the locations of the metallized holes according to the metallized half-hole patterns formed by secondary external light imaging. Using precision milling cutter equipment, the intersecting grooves are milled out at the locations of the metallized holes. The shape, size and depth of the intersecting grooves need to be strictly controlled according to the design requirements to ensure that the metallized half-holes can meet the subsequent use requirements.

[0075] In the alkaline etching step, the circuit board after the intersecting grooves are milled needs to be alkaline etched to remove the unnecessary copper layer and obtain the required metallized half-hole. Select an appropriate alkaline etching solution to ensure that it can completely etch away the unnecessary copper layer without damaging the plated tin layer and other parts of the circuit board. Place the circuit board after the intersecting grooves are milled in the alkaline etching solution and maintain it for a certain time and temperature. The etching solution needs to be gently stirred during the etching process to ensure a uniform etching effect. After etching is completed, use clean water or a special cleaning agent to thoroughly clean the circuit board to remove residual etching solution and impurities. Then, put the circuit board into an oven for drying to remove moisture and prepare for subsequent processing steps.

[0076] In some embodiments of the present invention, the step of making the outer layer circuit further includes the following steps: an outer layer etching inspection, after the etching process of the outer layer circuit of the circuit board is completed, the etching result is inspected and tested. In the outer layer etching inspection step, after the etching process of the outer layer circuit of the circuit board is completed, the etching result needs to be inspected and tested to ensure that the quality of the outer layer circuit meets the design requirements.

[0077] Specifically, first, visually inspect the surface of the circuit board to see if the outer circuit is clear and complete, and whether there are defects such as open circuit, short circuit or uneven line thickness. At the same time, check whether the surface of the circuit board is flat and whether there are pits, protrusions or scratches. Then, special electrical performance test equipment can be used to test the conductivity and insulation of the outer circuit. The conductivity test mainly checks whether the connection between the circuits is good, whether there is a circuit break or poor contact; the insulation test checks whether the insulation performance between the circuits meets the standard, whether there is a short circuit or leakage. You can also use precision measuring tools to measure the dimensions of the outer circuit, including line width, spacing, line length, etc. Compare the measurement results with the design requirements to ensure that the line dimensions meet the design requirements. Record the inspection results and test data in detail, and analyze and evaluate them. If problems or abnormalities are found, feedback to the production department or relevant person in charge in a timely manner for rectification or re-production. Through an outer layer etching inspection step, problems that may occur during the outer layer circuit etching process can be discovered and corrected in a timely manner, ensuring that the quality and accuracy of the outer layer circuit meet the design requirements, providing reliable protection for subsequent processing and use.

[0078] Furthermore, in some embodiments of the present invention, after the step of making the metallized half hole, the following steps are also included: secondary outer layer etching inspection, after the metallized half hole etching process of the circuit board is completed, the etching result is inspected and tested. Similarly, after the step of making the metallized half hole, the step of secondary outer layer etching inspection is also added to ensure the quality and accuracy of the metallized half hole etching. Specifically including: visual inspection, electrical performance testing, dimensional measurement, recording and feedback, etc., which have been described in the above embodiments, and will not be repeated in this embodiment.

[0079] The embodiment of the second aspect of the present invention further provides an optical module circuit board with a metallized half hole. According to the optical module circuit board of the embodiment of the second aspect of the present invention, the optical module circuit board is manufactured using the manufacturing method of the optical module circuit board of any one of the embodiments of the first aspect. The optical module circuit board manufactured using the manufacturing method of the optical module circuit board of any one of the embodiments of the first aspect can reduce the problems of etching the metallized half hole into copper-free by acid etching in the negative film process and the failure to ensure the requirements of the optical module product for the top of the line in the alkaline etching of the positive film process, so that the optical module circuit board can have higher quality, thereby reducing costs.

[0080] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A method for manufacturing an optical module circuit board, characterized in that: The following steps are involved: Drilling: drilling through holes on the circuit board to connect the layers; Copper deposition, an oxidation-reduction reaction is carried out on the circuit board after drilling to form a copper layer on the hole wall to metallize the through hole; Make the outer circuit, and use negative film process to make the outer circuit pattern of the circuit board; as well as Make metallized half holes and use positive film process to make metallized half holes of circuit boards.

2. The method for manufacturing an optical module circuit board according to claim 1, characterized in that: The step of making the outer layer circuit also includes the following steps: One-time external light imaging, using dry film as a carrier in the circuit process, and exposing the circuit pattern required for the outer layer of the circuit board on the dry film through pattern transfer; Acid etching, after removing the unexposed dry film, exposes the outer copper surface, and uses acid etching solution to etch the copper surface to obtain the required circuit pattern.

3. The method for manufacturing an optical module circuit board according to claim 2, characterized in that: The one-time external light imaging step also includes the following steps: Lamination: placing the dry film on top of the circuit board and laminating it with a laminator; Exposure: placing the laminated circuit board in the exposure area of ​​the exposure equipment, and adjusting the exposure time and light intensity to make the photosensitive material on the dry film react chemically under the action of ultraviolet light; and Development: Place the exposed circuit board into the developer to remove the dry film on the unexposed part through chemical action.

4. The method for manufacturing an optical module circuit board according to claim 1, characterized in that: The step of making the metallized half hole comprises the following steps: Secondary external light imaging, using dry film as a carrier in the circuit process, exposing the position of the metallized half hole on the dry film through pattern transfer; Copper-tin plating: electroplating copper and tin on the circuit board to increase the thickness of the copper layer and provide corrosion protection; Milling the intersecting grooves, using a milling cutter to mill the intersecting grooves at the locations of the metallized holes of the circuit board, and processing the required metallized half holes; and Alkaline etching: The circuit board after milling the intersecting grooves is subjected to alkaline etching to remove the unnecessary copper layer and obtain the required metallized half-hole.

5. The method for manufacturing an optical module circuit board according to claim 4, characterized in that: The copper-tin plating step comprises the following steps: Pre-treatment: Before the copper-tin plating step, the circuit board is cleaned to remove impurities on the surface; Activation treatment: before the copper-tin plating step, the circuit board is activated to enhance the bonding strength between layers; Copper plating: the cleaned and activated circuit board is placed in a copper plating tank, and the copper ions are reduced to copper atoms and deposited on the surface of the circuit board through the action of electric current; and Tin plating: After copper plating is completed, the circuit board is placed in a tin plating tank for tin plating.

6. The method for manufacturing an optical module circuit board according to claim 1, characterized in that: The step of making the outer layer circuit also includes the following steps: An outer layer etching inspection is to check and test the etching results after the outer layer etching process of the circuit board is completed.

7. The method for manufacturing an optical module circuit board according to claim 1, characterized in that: The step of making the metallized half hole also includes the following steps: Secondary outer layer etching inspection: After the metallization half-hole etching process of the circuit board is completed, the etching results are inspected and tested.

8. An optical module circuit board with metallized half holes, characterized in that: The optical module circuit board is manufactured by the manufacturing method of any one of claims 1 to 7.

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