CN111970831A

CN111970831A - Manufacturing process of T-shaped high-rise copper-buried circuit board

Info

Publication number: CN111970831A
Application number: CN202010897290.XA
Authority: CN
Inventors: 孙保玉; 徐瑞国; 刘海涛
Original assignee: Zhuhai Chongda Circuit Technology Co ltd; Shenzhen Suntak Multilayer PCB Co Ltd
Current assignee: Zhuhai Chongda Circuit Technology Co ltd; Shenzhen Suntak Multilayer PCB Co Ltd
Priority date: 2020-08-31
Filing date: 2020-08-31
Publication date: 2020-11-20
Anticipated expiration: 2040-08-31
Also published as: CN111970831B

Abstract

The invention discloses a manufacturing process of a T-shaped high-rise copper-buried circuit board, which comprises the following steps: after the core plate and the PP sheet are cut, respectively drilling a positioning hole at four corners of the core plate and the PP sheet; positioning by four positioning holes, forming a first window on the core plate and the PP sheet corresponding to the position with larger size at the upper end of the T-shaped copper block, and forming a second window on the core plate and the PP sheet corresponding to the position with smaller size at the lower end of the T-shaped copper block; then, inner layer circuits are manufactured on the core board; sequentially overlapping the core plate and the PP sheet according to requirements, forming stepped slotted holes at the corresponding first windowing positions and the second windowing positions, putting the T-shaped copper blocks into the stepped slotted holes, and pressing to form a production plate; and then carrying out post-processing on the production board to obtain the T-shaped high-rise buried copper circuit board. The four-point positioning drilling method is adopted, so that the vertical accurate alignment of the stepped slotted holes is realized, the positions of the copper blocks are relatively fixed and kept flat, the product quality is improved, and the rejection rate is reduced.

Description

Manufacturing process of T-shaped high-rise copper-buried circuit board

Technical Field

The invention relates to the technical field of printed circuit board manufacturing, in particular to a manufacturing process of a T-shaped high-rise copper-buried circuit board.

Background

With the continuous miniaturization of electronic products, the volume of a Printed Circuit Board (PCB) is required to be continuously reduced, and the circuit design is more and more intensive; the power density of the components is improved, and the heat dissipation capacity of the PCB is overlarge, so that the problems of short service life of the components, aging, even failure of the components and the like are caused; an explosion event of a certain known mobile phone battery is a typical example, so that designers and manufacturers are more vigilant in terms of heat dissipation; this event again demonstrates the desirability of improving thermal management of electronic products.

The copper-embedded PCB is characterized in that a copper block is partially embedded in the PCB, a high-power component is directly attached to the surface of the copper-embedded block, and heat is conducted out through the copper block. Due to the advantages of high heat-conducting property, small position space, low manufacturing cost and the like, the copper-embedded PCB is widely applied to the fields of RFID, communication base stations, antenna communication equipment, amplifiers, military products and the like. At present, the industry embedded copper PCB is divided into a copper block semi-embedded type and a copper block penetrating type; for the copper block semi-buried type, the buried copper slot hole is a blind hole with one end opened and the other section closed, the copper block can be better fixed in the slot hole, and the pressing alignment and the flatness of the copper block and the plate surface can be well controlled; for the copper block through type, the buried copper slot hole penetrates through the whole board surface, so the copper block through type PCB has higher requirements on the technological level, such as press alignment, flatness of the copper block and the board surface, appearance, dent control of the joint of the copper block and FR4, and the like, and is generally applied to an L4-L6 laminate at present, but relatively less applied to a high-rise circuit board with high requirement on the interlayer alignment precision.

The existing copper block through type copper plate embedding manufacturing technology cannot meet the manufacturing quality requirement of an L14 high-level copper circuit board, the traditional manufacturing process is adopted, namely, inner layer pattern manufacturing is completed firstly, then slotted holes in a core plate and a PP plate are milled, OPE punching is performed, and pressing is completed finally through browning and pre-stacking. According to the process, in the processes of milling the slotted hole on the core board and punching the OPE, the board is etched to be thin and has insufficient strength, so that the board is easy to deform under pressure, the defect that a copper block cannot be plugged into the copper-embedded slotted hole in the later period is caused, the alignment of each inner layer circuit is influenced, the layer deviation is caused, the inner layer short circuit defect is caused, the accurate alignment of the copper block and the slotted hole is difficult to realize, and each layer of core board is extruded by the copper block to generate large deformation and layer deviation, so that the inner layer short circuit defect is caused; meanwhile, the inclination of the embedded copper block also easily causes the problems of plate surface depression, hole position deviation of drilling holes and the like, and the first-time manufactured electrical measurement yield is only 45.7%.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a manufacturing process of a T-shaped high-rise buried copper circuit board, which realizes the vertical and accurate alignment of stepped slotted holes by adopting a four-point positioning and drilling method, relatively fixes and keeps the positions of copper blocks flat, can effectively avoid the problems of plate surface depression, outer layer drilling hole position offset, larger deformation and layer offset of each layer of core board caused by the inclination of the copper blocks, improves the product quality and reduces the rejection rate.

In order to solve the technical problem, the invention provides a manufacturing process of a through T-shaped high-rise copper-buried circuit board, wherein the through T-shaped high-rise copper-buried circuit board is a multilayer board formed by laminating a plurality of core boards into a laminated board by PP sheets and then pressing the laminated board into a whole, a step-shaped groove hole for accommodating a T-shaped copper block is arranged on the through T-shaped high-rise copper-buried circuit board in a penetrating way, and the manufacturing process comprises the following steps:

s1, a plurality of core plates and a plurality of PP sheets are cut according to the size of the jointed board, and positioning holes are drilled at the corresponding positions of the four corners of the core plates and the PP sheets respectively;

s2, positioning by four positioning holes, forming a first window on the core board and the PP sheet corresponding to the position with larger size at the upper end of the T-shaped copper block, and forming a second window on the core board and the PP sheet corresponding to the position with smaller size at the lower end of the T-shaped copper block;

s3, positioning by four positioning holes, and manufacturing an inner layer circuit on the core plate through a negative film process;

s4, sequentially overlapping the core plate and the PP sheet according to requirements, forming stepped slotted holes at the corresponding first windowing positions and the second windowing positions, putting the T-shaped copper block into the stepped slotted holes, and pressing to form a production plate; the core plate with the first window and the PP sheet are positioned at the upper end of the production plate, and the core plate with the second window and the PP sheet are positioned at the lower end of the production plate;

and S5, sequentially performing outer layer drilling, copper deposition, whole board electroplating, outer layer circuit manufacturing, solder mask manufacturing, surface treatment and molding on the production board to obtain the T-shaped high-level buried copper circuit board.

Furthermore, the distances between the positions of the four positioning holes and the edges of the two sides are all more than or equal to 30mm and less than or equal to 50 mm.

Further, in step S1, after the positioning holes are drilled, a one-direction hole is drilled on a connection line of two of the positioning holes.

Furthermore, the distance between the direction hole and one of the positioning holes is more than or equal to 10mm and less than or equal to 20 mm.

Further, in step S2, the plurality of core boards and the plurality of PP sheets for opening the first window are respectively stacked together and fixed on the processing table by four positioning holes in a manner of fixing with pins, and then positioned by the four positioning holes, and then the first window is drilled or routed on the plurality of core boards and the plurality of PP sheets; a plurality of core plates and a plurality of PP sheets for opening the second windows are respectively overlapped together and fixed on the processing table board through four positioning holes in a pin fixing mode, then the positioning is carried out through the four positioning holes, and then the second windows are drilled or milled on the plurality of core plates and the plurality of PP sheets.

Further, in step S2, the total thickness of the stacked core plates should be less than or equal to 3.0mm or the total number of the stacked core plates should be no more than 20; the total thickness of the stacked PP sheets is less than or equal to 3.0mm or the total number of the stacked PP sheets is less than or equal to 25.

Further, in step S3, an LDI exposure machine is used during exposure, and the opening on the core board is kept through front and back during etching the inner layer circuit.

Further, in step S4, the core board and the PP sheet are sequentially overlapped as required, and then riveted by rivets passing through four corresponding positioning holes, and then the T-shaped copper block is placed into the stepped slot hole.

Further, in step S4, the size of the T-shaped copper block is smaller by 0.076mm on one side than the size of the stepped slot hole.

Further, in the outer layer drilling step of step S5, when the drilled holes include holes drilled through the sheet material at the upper end and the lower end of the T-shaped copper block, the holes are drilled in a step-by-step drilling manner, the holes in the T-shaped copper block are drilled first, and then the holes in the sheet material are drilled, and the drill bit rotation speed when the holes in the T-shaped copper block are drilled is greater than the drill bit rotation speed when the holes in the sheet material are drilled.

Compared with the prior art, the invention has the following beneficial effects:

the invention optimizes the process flow and adopts a four-point positioning and drilling method, all the core plates and PP are positioned by adopting the same four positioning holes when windowing, so that the windowing of all the core plates and PP is vertically and accurately aligned and step-shaped slotted holes are formed after the plates are superposed in the pressing procedure, and the method combines the exposure positioning of the inner layer pattern and the windowing positioning of the drilling hole, namely the exposure positioning hole of the inner layer pattern adopts the positioning hole which is the same as the windowing of the drilling hole, so that the relative position between the windowing position and the positioning point of the core plate after the transfer of the inner layer pattern is fixed, and the vertical alignment of the windowing after the plates are superposed is realized; the method comprises the steps of drilling a positioning hole, windowing and then making an inner layer pattern, solving the defect that a copper-embedded block cannot be plugged into a copper-embedded slotted hole due to the fact that a core board is firstly used for manufacturing an inner layer circuit and then the windowing is easy to deform in the existing method, and also solving the defect that slotted holes between drilled layers are not aligned due to the fact that the core board and PP deviate when an OPE punches holes after the inner layer pattern is transferred in the existing method; four-point positioning is adopted to ensure that tool holes are not dissociated outside the board surface when the core board and the PP are drilled, so that the problem that the board cannot be arranged or the defect that the positions of the slotted holes deviate after the board arrangement is fixed is avoided; still provide and adopt T type copper billet and echelonment slotted hole complex mode, make the position relatively fixed of T type copper billet and keep leveling, can effectively avoid the face that the copper billet slope leads to sunken, outer drilling hole site skew and each layer core receive the copper billet extrusion to produce great deformation and layer partially scheduling problem, promoted product quality, reduced the disability rate.

Detailed Description

In order to more fully understand the technical contents of the present invention, the technical solutions of the present invention will be further described and illustrated with reference to specific embodiments.

Examples

The embodiment provides a manufacturing process of a 14-layer through T-shaped high-layer copper-buried circuit board, wherein a stepped slot hole for accommodating a T-shaped copper block is formed in the through T-shaped high-layer copper-buried circuit board in a penetrating mode, and the specific process is as follows:

(1) cutting: 7 core plates and a plurality of PP sheets are cut according to the size of the jointed board of 467mm multiplied by 620mm, the thickness of the core plate is 0.2mm (the thickness is the thickness without outer layer copper foil), and the thickness of the outer layer copper foil is 0.5 oz.

(2) Inner layer drilling: and respectively drilling a positioning hole at four corners of all the core plates and the PP sheet, and drilling a directional hole on a connecting line of two positioning holes.

In order to ensure the alignment accuracy of drilling positions in the later lamination, all the core plates and the PP adopt uniform drilling belt parameters when the positioning holes and the direction holes are drilled, the distance between the positions of the four positioning holes and the edges of two sides is more than or equal to 30mm and less than or equal to 50mm, and the distance between the direction hole and one of the positioning holes is more than or equal to 10mm and less than or equal to 20 mm.

(3) And (3) superposing: respectively overlapping 3 core plates and part of PP sheets and fixing the core plates and part of PP sheets on a processing table board in a pin fixing mode through four positioning holes; in addition, the rest 4 core plates and the rest PP sheets are respectively overlapped together and fixed on the processing table board through four positioning holes in a pin fixing mode.

In order to ensure the alignment accuracy of later windowing, the total thickness of the stacked core plates is less than or equal to 3.0mm or the total number of the stacked core plates is less than or equal to 20; the total thickness of the stacked PP sheets is less than or equal to 3.0mm or the total number of the stacked PP sheets is less than or equal to 25.

(4) And windowing: positioning is carried out through four positioning holes and directional holes, according to the relative position of a T-shaped copper block and the positioning holes which need to be arranged, a phenolic aldehyde cover plate is adopted, a first window is drilled or milled at the position where the copper blocks are correspondingly embedded on 3 superposed core plates and part of PP plates, and the first window is matched and corresponds to the larger part of the upper end of the T-shaped copper block; and drilling or routing a second window at the position of the corresponding buried copper block on the 4 core plates and the residual PP plates which are overlapped together, wherein the first window is matched and corresponds to the larger part of the upper end of the T-shaped copper block, namely the size of the first window is larger than that of the second window.

Wherein, when the diameter or side length of the window to be opened is less than or equal to 6.5mm, the window is opened by adopting a drilling mode; when the diameter or side length of the window to be opened is larger than 6.5mm, the window is opened by adopting a hole milling mode.

(5) And inner layer circuit manufacturing (negative film process): transferring inner layer patterns, coating a photosensitive film by using a vertical coating machine, controlling the film thickness of the photosensitive film to be 8 microns, adopting an LDI (laser direct structuring) exposure machine, completing inner layer circuit exposure on all core plates by using a 5-6-grid exposure ruler (21-grid exposure ruler), not performing exposure at a windowing position on the core plates during exposure, forming an inner layer circuit pattern after development, developing and removing the film at the windowing position, keeping the windowing position on the core plates to be transparent front and back during development and later etching, preventing an exposed dry film at the windowing position from being broken by flowing liquid during development and etching stages to cause core plate defects, and reducing residual copper defects after etching; etching the inner layer, etching the exposed and developed core board to form an inner layer circuit, wherein the line width of the inner layer is measured to be 3 mil; and (4) inner layer AOI, and then, detecting defects of an inner layer circuit, such as open short circuit, circuit notch, circuit pinhole and the like, and performing defect scrapping treatment, wherein a defect-free product is discharged to the next flow.

(6) And brown oxidation: the method comprises the following steps of carrying out browning treatment on a T-shaped copper block, fixing the T-shaped copper block by using a porous partition plate, carrying out browning, properly increasing the browning times or reducing the browning speed to ensure that each surface of the copper block is browned completely, clamping the T-shaped copper block between two porous light plates, and effectively avoiding the problem of collision and scratching between the copper blocks, wherein the T-shaped copper block and a bearing tool (the porous partition plate) are placed in an oven to be dried together after the browning so as to obtain the completely dried browning copper block.

(7) And pressing: browning speed according to the thickness of copper at the bottom, sequentially superposing a core plate and PP sheets (the order of the laminated plate is that the core plate, the PP sheets, the core plate, the … … core plate, the PP sheets and the core plate, namely, the core plate and the core plate are separated by the PP sheets, 3 core plates with first windows and the PP sheets are positioned at the upper end of the order of the laminated plate, and 4 core plates with second windows and the PP sheets are positioned at the lower end of the order of the laminated plate) according to requirements, and then riveting by using rivets to penetrate through four positioning holes corresponding to the upper part and the lower part to form the laminated plate, at this time, stepped slots are formed at the first windows and the second windows corresponding to the core plate and the PP sheet, then, lightly clamping the T-shaped copper block by using tweezers and putting the T-shaped copper block into the stepped slotted hole to enable the T-shaped copper block to be smoothly embedded into the stepped slotted hole and ensure that the peripheral side walls of the copper block are completely free of scratching, and then pressing the T-shaped copper block into a production plate by selecting proper lamination conditions according to the characteristics of the plate; the size of the T-shaped copper block is 0.076mm smaller than that of the stepped slotted hole on one side, so that the copper block can be conveniently placed and filled with glue, and the copper block and the plate can be reliably bonded; the core plate with the first window and the PP sheet are positioned at the upper end of the production plate after lamination, and the core plate with the second window and the PP sheet are positioned at the lower end of the production plate.

The mode of plate stacking is Pin-Lam, riveting, fusion + riveting, riveting + Pin-Lam and fusion + Pin-Lam.

After the laminated plate is laminated and the T-shaped copper block is placed, sequentially laminating a release film, an aluminum sheet and a buffer pad on the upper surface and the lower surface of the laminated plate from inside to outside, and ensuring that the pressure is uniformly and slowly acted on the upper side and the lower side in the pressing process so that the upper surface and the lower surface of the T-shaped copper block are flush with the plate surface; in the plate arranging process, the overlapped plate embedded with the T-shaped copper block needs to be ensured to be translated to the operation platform, bending is avoided, the copper block is prevented from falling off, whether the copper block falls off or deviates is checked before the release film is covered, and the copper block is ensured to be embedded into the slotted hole in a preset mode.

(8) Removing the flowing glue: the production plate is firstly subjected to glue removal twice by adopting a non-woven fabric grinding plate, and then is subjected to chemical glue removal once or is manually ground by adopting 600# and 200# abrasive paper, so that no glue flowing on the surface of the T-shaped copper block is ensured, and the surface of the plate is kept flat.

(9) And outer layer drilling: drilling holes on the production plate in a mechanical drilling mode according to the drilling data; when the drilled holes comprise holes which penetrate through the plate materials at the upper end and the lower end of the T-shaped copper block (namely holes are drilled at the position where the copper block and the plate material coincide), according to the characteristics of the copper block and the plate material, the holes are drilled in a step-by-step drilling mode by adopting different drilling strip parameters, the holes in the T-shaped copper block are drilled firstly, then the holes in the plate material are drilled, the rotating speed of a drill bit when the holes in the T-shaped copper block are drilled is larger than that when the holes in the plate material are drilled, and the copper batch cutting edge and the resin batch cutting edge can be reduced or avoided by adopting the step-by-step drilling mode and utilizing the different drilling strip parameters.

(10) And copper deposition: a layer of thin copper is deposited on the hole wall in a chemical reaction mode to provide a foundation for the subsequent full-board electroplating, the backlight test is 10 grades, and the thickness of the copper deposition in the hole is 0.5 mu m.

(11) And electroplating the whole plate: according to the mechanism of electrochemical reaction, a layer of copper is electroplated on the basis of copper deposition, the thickness of the hole copper is ensured to meet the product requirement, and electroplating parameters are set according to the thickness of the finished hole copper.

(12) And manufacturing an outer layer circuit (positive process): transferring an outer layer pattern, completing outer layer line exposure by using a full-automatic exposure machine and a positive film line film with 5-7 exposure rulers (21 exposure rulers), and forming an outer layer line pattern on a production board through development; electroplating an outer layer pattern, then respectively plating copper and tin on the production plate, setting electroplating parameters according to the required finished copper thickness, wherein the copper plating is carried out for 60min at the current density of 1.8ASD, and the tin plating is carried out for 10min at the current density of 1.2ASD, and the tin thickness is 3-5 mu m; then sequentially removing the film, etching and removing tin, and etching an outer layer circuit on the production board; and the outer layer AOI uses an automatic optical detection system to detect whether the outer layer circuit has the defects of open circuit, gap, incomplete etching, short circuit and the like by comparing with CAM data.

(13) Solder resist and silk screen printing of characters: by making a green oil layer on the outer layer of the production plate and silk-printing characters, the thickness of the green oil is as follows: 10-50 μm, so that the influence of environmental change on the production plate can be reduced in the subsequent use process.

(14) Surface treatment (nickel-gold deposition): the copper surface of the welding pad at the solder stop windowing position is communicated with a chemical principle, a nickel layer and a gold layer with certain required thickness are uniformly deposited, and the thickness of the nickel layer is as follows: 3-5 μm; the thickness of the gold layer is as follows: 0.05-0.1 μm.

(15) And electrical test: testing the electrical conduction performance of the finished board, wherein the board use testing method comprises the following steps: and (5) flying probe testing.

(16) And forming: according to the prior art and according to the design requirement, the shape is gong, and the tolerance of the shape is +/-0.05 mm; and manufacturing a 14-layer through T-shaped high-level copper-buried circuit board.

(17) FQC: according to the customer acceptance standard and the I's inspection standard, the appearance of the T-shaped high-level buried copper circuit board is inspected, if a defect exists, the defect is repaired in time, and the excellent quality control is guaranteed to be provided for the customer.

(18) FQA: and measuring whether the appearance, the hole copper thickness, the dielectric layer thickness, the green oil thickness, the inner layer copper thickness and the like of the T-shaped high-rise buried copper circuit board meet the requirements of customers or not.

(19) And packaging: and hermetically packaging the T-shaped high-rise buried copper circuit boards according to the packaging mode and the packaging quantity required by customers, putting a drying agent and a humidity card, and then delivering.

The technical solutions provided by the embodiments of the present invention are described in detail above, and the principles and embodiments of the present invention are explained herein by using specific examples, and the descriptions of the embodiments are only used to help understanding the principles of the embodiments of the present invention; meanwhile, for a person skilled in the art, according to the embodiments of the present invention, there may be variations in the specific implementation manners and application ranges, and in summary, the content of the present description should not be construed as a limitation to the present invention.

Claims

1. A manufacturing process of a T-shaped high-rise copper-buried circuit board is characterized by comprising the following steps of:

2. The manufacturing process of the through T-shaped high-rise copper-buried circuit board according to claim 1, wherein the distance between the position of each of the four positioning holes and the edge of each of the two sides is greater than or equal to 30mm and less than or equal to 50 mm.

3. The process of claim 1, wherein in step S1, after the positioning holes are drilled, a hole in one direction is drilled on the connecting line of two positioning holes.

4. The manufacturing process of the through T-shaped high-rise copper-buried circuit board according to claim 3, wherein the distance between the directional hole and one of the positioning holes is greater than or equal to 10mm and less than or equal to 20 mm.

5. The manufacturing process of the through T-shaped high-rise copper-buried circuit board according to claim 1, wherein in step S2, the plurality of core boards and the plurality of PP sheets for forming the first window are respectively overlapped together and fixed on the processing table board through four positioning holes in a pin fixing manner, then the positioning is carried out through the four positioning holes, and then the first window is drilled or milled on the plurality of core boards and the plurality of PP sheets; a plurality of core plates and a plurality of PP sheets for opening the second windows are respectively overlapped together and fixed on the processing table board through four positioning holes in a pin fixing mode, then the positioning is carried out through the four positioning holes, and then the second windows are drilled or milled on the plurality of core plates and the plurality of PP sheets.

6. The process for manufacturing a through T-shaped high-rise copper-buried circuit board according to claim 5, wherein in step S2, the total thickness of the stacked core boards is less than or equal to 3.0mm or the total number of the stacked core boards is less than or equal to 20; the total thickness of the stacked PP sheets is less than or equal to 3.0mm or the total number of the stacked PP sheets is less than or equal to 25.

7. The process of claim 1, wherein in step S3, an LDI exposure machine is used for exposure, and the openings of the core board are kept through during etching to form the inner layer circuits.

8. The process for manufacturing the through T-shaped high-rise copper-embedded circuit board according to claim 1, wherein in the step S4, the core board and the PP sheet are sequentially overlapped according to requirements, then the core board and the PP sheet are riveted by rivets passing through four corresponding positioning holes from top to bottom, and then the T-shaped copper block is placed in the stepped slotted hole.

9. The process for manufacturing a through T-shaped high-rise copper-buried circuit board according to claim 1, wherein in step S4, the size of the single side of the T-shaped copper block is 0.076mm smaller than the size of the stepped slot hole.

10. The process for manufacturing a through T-shaped high-rise copper-buried circuit board according to claim 1, wherein in the outer layer drilling step of step S5, when the drilled holes include holes drilled through the sheet material at the upper end and the lower end of the T-shaped copper block, the holes are drilled in a step-by-step drilling manner, the holes in the T-shaped copper block are drilled first, then the holes in the sheet material are drilled, and the rotating speed of a drill bit during drilling the holes in the T-shaped copper block is greater than the rotating speed of the drill bit during drilling the holes in the sheet material.