Method for manufacturing gold-plated pressed structure of stepped circuit board

Abstract

The present invention provides a method for manufacturing a gold-plated pressed structure of a stepped circuit board, comprising the steps of: plating soft gold on the inner layer, applying brown glue, controlling the glue flow at the stepped cavity, and uncovering. The present invention plates soft gold on the inner layer of the stepped circuit board, and the soft gold plating has a relatively small hardness, a soft texture, and a high purity. Therefore, the reliability of welding is improved, and the risk of components falling off after being installed by customers can be prevented, which is conducive to ensuring that components are not accidentally installed in harsh environments.

Description

Technical Field

[0001] The invention relates to the field of circuit board manufacturing, and in particular to a method for manufacturing a gold-plated pressing structure of a stepped circuit board. Background Art

[0002] The electronics industry is now in a stage of rapid development, especially for circuit boards used in the aerospace field. The circuit boards have strict requirements on welding reliability. It is necessary to ensure that components do not fail in harsh environments, especially to prevent components from falling off due to unreliable welding. However, when components are welded to step circuit boards, due to the high hardness of conventional gold-plated surfaces, reliability issues will occur when welding components to them, such as the risk of components falling off after welding. Summary of the invention

[0003] The present invention provides a method for manufacturing a gold-plated pressing structure of a stepped circuit board to solve at least one of the above-mentioned technical problems.

[0004] To solve the above problems, as one aspect of the present invention, a method for manufacturing a stepped circuit board gold-plated pressing structure is provided, comprising:

[0005] Step 1: produce the inner blind holes and lines of the L1 / 2 layer, and produce the other layers below according to the expansion and contraction coefficient of the L1 / 2 layer to prevent abnormal expansion and contraction and lamination deviation and short circuit;

[0006] Step 2, L1 / 2 cutting - drilling 1 - copper plating - board plating - plated hole dry film - plated hole - internal photo imaging - internal photo etching - inner layer targeting - inner layer AOI, according to this normal inner layer process to produce L1 / 2 mechanical blind holes and inner layer circuits;

[0007] Step 3, L3 / L4 cutting, measuring the expansion and contraction coefficient of the L1 / 2 inner layer after etching, and making the L3 inner layer soft gold plating pattern;

[0008] Step 4, soft gold plating: soft gold is plated on the board surface of the inner layer of L3 according to the pattern at the step cavity of the inner layer of L3;

[0009] Step 5, film stripping: After soft gold plating, the soft gold plated pattern dry film is stripped off to make the L3 / L4 inner layer circuit pattern;

[0010] Step 6, internal light imaging 2: Make L3 / L4 inner layer circuit pattern, but when making the pattern, the soft gold-plated area must be covered with dry film to prevent the gold surface from being corroded during the inner layer etching;

[0011] Step 7, inner layer etching, film stripping: forming inner layer L3 / L4 circuit pattern;

[0012] Step 8, apply brown glue: Use brown glue to cover and protect the soft gold pattern gold surface of the inner layer L3;

[0013] Step 9, cutting the PP layer, measuring the expansion and contraction coefficient of the L1-2 inner layer after etching, and drilling the PP positioning hole according to the coefficient of the L1-2 inner layer after etching;

[0014] Step 10, gong PP layer; gong the PP layer according to the step cavity for standby use, but the size of the cavity during gong PP is increased by 3mil on one side based on the original customer design size to prevent serious glue flow during pressing and to avoid glue contamination of the gold surface. The gong PP belt coefficient refers to the coefficient after etching of the 1-2 inner layer to avoid the asymmetry of the cavity position of the gong and the step position of the inner layer of the L1-2 layer, which leads to scrapping;

[0015] Step 11, L1 / 4 layer production, browning, pressing, after the core board is browned, the L1-4 inner core board and PP are all pressed together to form the outer copper plate;

[0016] Step 12, removing glue and treating the residual glue on the pressed board surface with chemical potassium permanganate;

[0017] Step 13, measuring the expansion and contraction, measuring the expansion and contraction coefficient of the outer copper plate, and drilling production is produced according to this coefficient;

[0018] Step 14, drilling holes in the outer copper plate to form through holes;

[0019] Step 15, copper deposition, plate plating, and chemical deposition are used to metallize the through hole wall, and then the hole copper and surface copper are thickened by 5-8um by plate plating; the hole is connected to the outer layer of copper to form a conductive channel;

[0020] Step 16, external light imaging, affix a layer of photosensitive dry film to the copper plate, use film to selectively expose and develop the outer layer circuit;

[0021] Step 17, copper plating, using electroplating to plate exposed copper lines, holes, and pads to the copper thickness required by the customer;

[0022] Step 18, plating the outer layer with soft gold; using electroplating, plating the exposed copper circuits, holes, and pads to the soft gold thickness required by the customer;

[0023] Step 19, etching the outer layer, first stripping the film, exposing all the copper to be etched, and etching away all the exposed copper after stripping the film to form a circuit;

[0024] Step 20, outer layer AOI, check if there are other abnormal problems;

[0025] Step 21, printing solder resist, printing a layer of solder resist ink on the circuit board, using film for selective exposure and development to form an effective soldering position pattern;

[0026] Step 22, controlled depth milling: the portion of the L1-L2 layer corresponding to the inner layer plated with soft gold and pasted with brown glue is milled by controlled depth milling until the cover can be removed, but the brown glue cannot be damaged;

[0027] Step 23, uncovering; after controlled depth milling, the cover is uncovered to form a stepped plate, and the inner brown glue is torn off to expose the inner soft gold-plated surface;

[0028] Step 24: normal electrical testing, milling, final inspection, and shipment.

[0029] In the above technical scheme, the present invention plates soft gold on the inner layer of the step circuit board. The hardness of the soft gold is relatively small, the texture is soft, and the purity of the soft gold is high. Therefore, the reliability of welding is improved, and the risk of components falling off after being installed by customers can be prevented, which is conducive to ensuring that there are no accidents in harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The structural diagram of the present invention is schematically shown;

[0031] Figure 2 The schematic diagram of the structure after the deep milling is schematically shown;

[0032] Figure 3 The schematic diagram of the structure after removing the brown glue is shown schematically.

[0033] Reference numerals in the figure: 1. L1 / L2 layer; 2. L3 / L4 layer; 3. PP layer; 4. Blind hole; 5. PP cavity; 6. Brown glue; 7. Soft gold plating; 8. Controlled depth milling area. DETAILED DESCRIPTION

[0034] The following is a detailed description of embodiments of the present invention, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0035] The present invention provides a stepped circuit board gold-plated pressing structure and a manufacturing method, which are mainly used to solve the reliability problem of component welding, including: using soft gold plating on the inner layer, pasting brown glue, controlling the glue flow at the stepped cavity (milling the PP window size), and uncovering, etc., specifically including the following steps:

[0036] Step 1: First, produce the inner blind holes and lines of the L1 / 2 layer, and then produce the other layers below according to the expansion and contraction coefficient of the L1 / 2 layer to prevent abnormal expansion and contraction and lamination deviation and short circuit;

[0037] Step 2, L1 / 2 cutting - drilling 1 - copper plating - board plating - plated hole dry film - plated hole - internal light imaging - internal light etching - inner layer targeting - inner layer AOI, according to this normal inner layer process to make L1 / 2 mechanical blind holes and inner layer circuits;

[0038] Step 3: First, cut the material, measure (expansion and contraction coefficient of L1-2 inner layer after etching), and make soft gold-plated patterns of inner layer L3 / L4;

[0039] Step 4: soft gold plating; plating soft gold on the board surface according to the pattern at the step cavity of the inner layer;

[0040] Step 5: film stripping; after soft gold plating, the soft gold plated pattern dry film is stripped off to make the inner layer circuit pattern;

[0041] Step 6: Internal photoimaging 2: Make L3 / L4 inner layer circuit patterns, but the soft gold-plated areas must be covered with dry film when making the patterns to prevent the gold surface from being corroded when the inner layer is etched;

[0042] Step 7: Inner layer etching and film stripping to form inner layer L3 / L4 circuit pattern;

[0043] Step 8: Apply brown glue to cover and protect the gold surface of the inner layer L3. First, make the inner layer soft gold pattern on the inner layer where the inner layer step cavity is located, then make the inner light circuit after stripping the film, and form the inner layer circuit pattern after etching. Use brown glue to cover the soft gold-plated area to prevent glue from flowing during pressing and contamination and damage to the gold surface when uncovering.

[0044] Step 9: First, cut the material, measure (expansion and contraction coefficient of L1-2 inner layer after etching), and drill the PP positioning hole according to the coefficient of L1-2 inner layer after etching;

[0045] Step 10: PP is gonged; the PP is gonged at the step cavity for standby use, but the size of the cavity is increased by 3mil on one side based on the original customer design size when gonging PP to prevent serious glue flow during pressing and to avoid glue contamination of the gold surface. The gong PP belt coefficient refers to the coefficient of gong PP after 1-2 inner layer etching to avoid the asymmetry of the cavity position of the gong and the step position of the inner layer of L1-2 layer, which leads to scrapping;

[0046] Step 11, L1 / 4 layer production, browning, pressing, after the core board is browned, the L1-4 inner core board and PP are all pressed together to form the outer copper plate;

[0047] Step 12, remove the glue, and use chemical potassium permanganate to remove the residual glue on the pressed board surface;

[0048] Step 13, measure the expansion and contraction coefficient of the outer copper plate, and the drilling production is produced according to this coefficient;

[0049] Step 14: Drill holes in the outer copper plate to form through holes;

[0050] Step 15, copper deposition, board plating, and chemical deposition are used to metallize the through hole wall, and then the hole copper and surface copper are thickened by 5-8um by board plating; the hole is connected to the outer layer of copper to form a conductive channel;

[0051] Step 16: External light imaging: affix a layer of photosensitive dry film to the copper plate, and use film to selectively expose and develop the outer circuit;

[0052] Step 17: Copper plating: Use electroplating to plate exposed copper lines, holes, and pads to the copper thickness required by the customer.

[0053] Step 18: Soft gold plating on the outer layer; electroplating is used to plate the exposed copper circuits, holes, and pads to the soft gold thickness required by the customer;

[0054] Step 19, outer layer etching, first stripping the film, exposing all the copper to be etched, etching away all the exposed copper after stripping the film, forming a circuit;

[0055] Step 20: Outer layer AOI to check if there are other abnormal problems;

[0056] Step 21, printing solder resist, printing a layer of solder resist ink on the circuit board, using film for selective exposure and development to form an effective soldering position pattern;

[0057] Step 22, controlled depth milling: Use the controlled depth milling method to mill the part of the inner layer previously plated with soft gold and pasted with brown glue until the cover can be removed, but the brown glue cannot be damaged;

[0058] Step 23, uncovering; after controlled depth milling, uncovering to form a stepped plate, tearing off the inner brown glue to expose the inner soft gold-plated surface;

[0059] Step 24: Normal electrical testing, milling, final inspection, and shipment.

[0060] In the above technical scheme, the present invention plates soft gold on the inner layer of the step circuit board. The hardness of the soft gold is relatively small, the texture is soft, and the purity of the soft gold is high. Therefore, the reliability of welding is improved, and the risk of components falling off after being installed by customers can be prevented, which is conducive to ensuring that there are no accidents in harsh environments.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a gold-plated pressed structure of a stepped circuit board, characterized in that: include: Step 1: produce the inner blind holes and lines of the L1 / 2 layer, and produce the other layers below according to the expansion and contraction coefficient of the L1 / 2 layer to prevent abnormal expansion and contraction and lamination deviation and short circuit; Step 2, L1 / 2 cutting - drilling 1 - copper plating - board plating - plated hole dry film - plated hole - internal photo imaging - internal photo etching - inner layer targeting - inner layer AOI, according to this normal inner layer process to produce L1 / 2 mechanical blind holes and inner layer circuits; Step 3, L3 / L4 cutting, measuring the expansion and contraction coefficient of the L1 / 2 inner layer after etching, and making the L3 inner layer soft gold plating pattern; Step 4, soft gold plating: soft gold is plated on the board surface of the inner layer of L3 according to the pattern at the step cavity of the inner layer of L3; Step 5, film stripping: After soft gold plating, the soft gold plated pattern dry film is stripped off to make the L3 / L4 inner layer circuit pattern; Step 6, internal light imaging 2: Make L3 / L4 inner layer circuit pattern, but when making the pattern, the soft gold-plated area must be covered with dry film to prevent the gold surface from being corroded during the inner layer etching; Step 7, inner layer etching, film stripping: forming inner layer L3 / L4 circuit pattern; Step 8, apply brown glue: Use brown glue to cover and protect the soft gold pattern gold surface of the inner layer L3; Step 9, cutting the PP layer, measuring the expansion and contraction coefficient of the L1-2 inner layer after etching, and drilling the PP positioning hole according to the coefficient of the L1-2 inner layer after etching; Step 10, gong PP layer; gong the PP layer according to the step cavity for standby use, but the size of the cavity during gong PP is increased by 3mil on one side based on the original customer design size to prevent serious glue flow during pressing and to avoid glue contamination of the gold surface. The gong PP belt coefficient refers to the coefficient after etching of the 1-2 inner layer to avoid the asymmetry of the cavity position of the gong and the step position of the inner layer of the L1-2 layer, which leads to scrapping; Step 11, L1 / 4 layer production, browning, pressing, after the core board is browned, the L1-4 inner core board and PP are all pressed together to form the outer copper plate; Step 12, removing glue and treating the residual glue on the pressed board surface with chemical potassium permanganate; Step 13, measuring the expansion and contraction, measuring the expansion and contraction coefficient of the outer copper plate, and drilling production is produced according to this coefficient; Step 14, drilling holes in the outer copper plate to form through holes; Step 15, copper deposition, plate plating, and chemical deposition are used to metallize the through hole wall, and then plate plating is used to thicken the hole copper and surface copper by 5-8um; Connect the hole to the outer copper layer and form a conductive channel; Step 16, external light imaging, affix a layer of photosensitive dry film to the copper plate, use film to selectively expose and develop the outer layer circuit; Step 17, copper plating, using electroplating to plate exposed copper lines, holes, and pads to the copper thickness required by the customer; Step 18, plating the outer layer with soft gold; using electroplating, plating the exposed copper circuits, holes, and pads to the soft gold thickness required by the customer; Step 19, etching the outer layer, first stripping the film, exposing all the copper to be etched, and etching away all the exposed copper after stripping the film to form a circuit; Step 20, outer layer AOI, check if there are other abnormal problems; Step 21, printing solder resist, printing a layer of solder resist ink on the circuit board, using film for selective exposure and development to form an effective soldering position pattern; Step 22, controlled depth milling: the portion of the L1-L2 layer corresponding to the inner layer plated with soft gold and pasted with brown glue is milled by controlled depth milling until the cover can be removed, but the brown glue cannot be damaged; Step 23, uncovering; after controlled depth milling, the cover is uncovered to form a stepped plate, and the inner brown glue is torn off to expose the inner soft gold-plated surface; Step 24: normal electrical testing, milling, final inspection, and shipment.

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