Circuit board partially metallized edge-coated laminate structure and processing thereof

Abstract

The application provides a circuit board local metallization edge covering laminated structure and a processing technology thereof, which comprises a first core plate, a first non-flowing PP layer, a second core plate, a second non-flowing PP layer and a third core plate arranged in sequence from top to bottom, conductive metal strips are formed on the first core plate, the second core plate and the third core plate, a first blind groove is formed on the surface of the first core plate facing the second core plate, a second blind groove is formed on the surface of the third core plate facing the second core plate, and a first through groove is formed on the first non-flowing PP layer. The application does not need to pre-metallize and edge cover all layers, then control deep milling to mill off the excess metallization edge covering layers and etch, thereby avoiding the problems of milling deep damage to the metallization edge covering layer and affecting the unit size quality caused by the control deep milling, and mass production can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of circuit board manufacturing, in particular to a circuit board local metallization edge covering lamination structure and a processing technology thereof. BACKGROUND

[0002] For high-frequency high-speed PCB circuit boards, it is required to perform metallization edge covering on the board edge groove to form a metallized board edge groove so that microwave signals cannot be radiated out from the PCB board edge. The existing metallization edge covering process is basically all-level metallization edge covering. When the board is a local-level metallization edge covering structure, the current industry general method is to first perform all-level metallization edge covering, then perform controlled depth milling to mill off the excess level metallization edge covering, and then etch.

[0003] The local edge covering process in the prior art is: cutting → inner layer etching → lamination → drilling → milling metal groove hole (including edge covering) → copper deposition → plate plating → outer light imaging → pattern electroplating → controlled depth milling → milling half hole → outer layer etching → solder mask → character → gold deposition → post-process.

[0004] The controlled depth milling off of the excess level metallization edge covering has the following disadvantages: (1) the conventional controlled depth milling depth tolerance is ±0.15mm, the precision is low, and the metallization edge covering layer is often damaged by milling too deep, which affects the quality and leads to scrap; (2) similar designs cannot be mass-produced; (3) because the controlled depth milling needs to mill off the excess level metallization edge covering tin layer in the unit, there is a risk of affecting the size of the unit. SUMMARY

[0005] The present application provides a circuit board local metallization edge covering lamination structure and a processing technology thereof to solve at least one of the above technical problems.

[0006] To solve the above problems, as one aspect of the present application, a circuit board local metallization edge covering lamination structure is provided, comprising: a first core plate, a first non-flowing PP layer, a second core plate, a second non-flowing PP layer, and a third core plate arranged in sequence from top to bottom, conductive metal strips are formed on the first core plate, the second core plate and the third core plate, a first blind groove is formed on the surface of the first core plate facing the second core plate, a second blind groove is formed on the surface of the third core plate facing the second core plate, a first through groove is formed on the first non-flowing PP layer, a second through groove is formed on the second core plate, a metal layer used as local metallization edge covering is formed on the inner wall of the second through groove, a third through groove is formed on the second non-flowing PP layer, the first blind groove, the first through groove, the second through groove, the third through groove and the second blind groove are arranged in position correspondence, and the first blind groove, the first through groove, the second through groove, the third through groove and the second blind groove are connected to form an internal blind groove cavity after the first core plate, the first non-flowing PP layer, the second core plate, the second non-flowing PP layer and the third core plate are pressed into an integral whole.

[0007] Preferably, the part of the first core plate corresponding to the first blind slot is formed with a first laser cutting slot in communication with the first blind slot by means of laser controlled depth cutting.

[0008] Preferably, the part of the third core plate corresponding to the second blind slot is formed with a second laser cutting slot in communication with the second blind slot by means of laser controlled depth cutting.

[0009] The present application also provides a circuit board local metalized edge processing technology, comprising the following steps:

[0010] Step 1, a first core plate, a first non-flowing PP layer, a second core plate, a second non-flowing PP layer, and a third core plate are sequentially arranged from top to bottom, wherein,

[0011] The first core plate and the third core plate comprise the following manufacturing steps 11-13:

[0012] Step 11, inner light imaging 1: at a certain temperature and pressure, dry film is attached to the plate surface, then the negative is aligned, and finally, the unshielded dry film of the negative is reacted by ultraviolet light irradiation on the exposure machine to form the required circuit pattern on the plate surface. Then, through the development section, the film that has not been irradiated is dissolved away by the action of the developing solution, exposing the first side area that needs to be etched, and the copper surface on the second side is protected by the dry film;

[0013] Step 12, inner layer etching: copper reacts with copper ions in the etching tank to produce subcopper, achieving etching effect to produce the first side circuit, and then through the film stripping tank, the film is dissolved away by the action of the alkaline solution, exposing the required circuit;

[0014] Step 13, laser pre-control depth cutting: laser pre-control depth cutting is performed from the first side according to the design data, with a pre-control depth groove width of 0.15mm, a depth of 0.2mm, a depth tolerance of ±0.05mm, and a remaining thickness guarantee of ≥0.15mm to prevent cutting through, forming a "hollow" shaped groove;

[0015] The second core plate comprises the following manufacturing steps 21-26:

[0016] Step 21, milling metal slot hole: using a 0.6mm milling cutter to mill the plate on the milling machine to mill out a long slot at the edge covering position;

[0017] Step 22, copper deposition / plate plating: using whole plate electroplating to thicken the edge covering position and the surface copper by 5-8um to connect the edge covering and the copper of the second core plate;

[0018] Step 23, outer light imaging: at a certain temperature and pressure, dry film is pasted on the plate surface, then the film is aligned with the negative, and finally, the unshielded dry film of the negative is reacted by ultraviolet light irradiation on the exposure machine, so that the required line pattern is formed on the plate surface, and then through the development section, the film not irradiated by light is dissolved away, and the area requiring copper-tin plating is exposed;

[0019] Step 24, pattern plating: a layer of metal copper and tin layer for anti-etching protection is plated on the conductive area on the plate;

[0020] Step 25, milling semi-hole: a 0.6mm milling cutter is used to mill the plate to mill off the positions not requiring metal edge covering at both ends;

[0021] Step 26, outer layer etching: under the action of alkali, the film is removed to expose the copper surface to be etched, copper and copper ions react in the etching tank to produce cuprous ions to achieve etching effect, and the tin layer is removed by the reaction of nitric acid and tin surface in the tin stripping tank to expose the copper surface of the line pad;

[0022] A 0.75mm milling cutter is used to mill the first non-flowable PP layer and the second non-flowable PP layer to mill out the first through groove and the third through groove with a width of 0.75mm;

[0023] Step 2, lamination: the first core plate, the second core plate, and the third core plate are laminated, then the first non-flowable PP layer and the second non-flowable PP layer are stacked, and after riveting with tube position nails, under the action of a certain temperature and pressure, the resin of the semi-cured sheet flows to fill the lines and the substrate, and when the temperature reaches a certain degree, solidification occurs to bond the layers together, and a blind groove structure is formed at the same time;

[0024] Step 3, drilling, copper plating / plate plating, outer light imaging 1, pattern plating, outer layer etching, solder mask / character on the plate body formed in step 2;

[0025] Step 4, laser cutting: laser cutting is performed on the upper and lower surfaces of the plate body formed in step 3, with a groove width of 0.15mm and a depth tolerance of ±0.05mm, and the pre-control depth remaining thickness is cut off.

[0026] Preferably, it further comprises: Step 5, gold plating: a layer of metal nickel and gold is deposited on the copper surface through a chemical displacement reaction.

[0027] According to the technical scheme, the present application does not need to pre-metalize the edges of all layers, then control the depth of milling to mill off the excess metalized edges, and then etch, thereby avoiding the problems of milling depth damage to the metalized edge layer and affecting the unit size quality caused by controlled depth milling, and mass production can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A schematic view of the laminated structure of the present application is shown;

[0029] Figure 2 A schematic view of the position of the laser cutting groove is shown;

[0030] Figure 3 A schematic view of the structure of the final product of the present application is shown.

[0031] In the drawing, reference numerals: 1, first core plate; 2, first non-flowable PP layer; 3, second core plate; 4, second non-flowable PP layer; 5, third core plate; 6, conductive metal strip; 7, first blind groove; 8, second blind groove; 9, first through groove; 10, second through groove; 11, metal layer; 12, third through groove; 13, first laser cutting groove; 14, second laser cutting groove; 15, cover stripping area; 16, green oil layer. DETAILED DESCRIPTION

[0032] The following detailed description of the embodiments of the present application is provided, but the present application can be implemented in various different ways limited and covered by the claims.

[0033] As an aspect of the present application, a circuit board local metallization edge covering laminated structure is provided, comprising: a first core plate 1, a first non-flowable PP layer 2, a second core plate 3, a second non-flowable PP layer 4, and a third core plate 5 arranged in order from top to bottom, conductive metal strips 6 are formed on the first core plate 1, the second core plate 3 and the third core plate 5, a first blind groove 7 is formed on the surface of the first core plate 1 facing the second core plate 3, a second blind groove 8 is formed on the surface of the third core plate 5 facing the second core plate 3, a first through groove 9 is opened on the first non-flowable PP layer 2, a second through groove 10 is opened on the second core plate 3, a metal layer 11 for local metallization edge covering is formed on the inner wall of the second through groove 10, a third through groove 12 is opened on the second non-flowable PP layer 4, the first blind groove 7, the first through groove 9, the second through groove 10, the third through groove 12, and the second blind groove 8 are arranged in position correspondence, after the first core plate 1, the first non-flowable PP layer 2, the second core plate 3, the second non-flowable PP layer 4, and the third core plate 5 are pressed into an integrated whole, the first blind groove 7, the first through groove 9, the second through groove 10, the third through groove 12, and the second blind groove 8 are connected to form an internal blind groove cavity.

[0034] Preferably, the part of the first core plate 1 corresponding to the first blind groove 7 is formed with a first laser cutting groove 13 in communication with the first blind groove 7 by laser depth control cutting.

[0035] Preferably, the part of the third core plate 5 corresponding to the second blind groove 8 is formed with a second laser cutting groove 14 communicating with the second blind groove 8 by means of laser depth-controlled cutting.

[0036] In the above technical solution, the first core plate 1, the first non-flowing PP layer 2, the second core plate 3, the second non-flowing PP layer 4, and the third core plate 5, and the conductive metal strip 6, the first blind groove 7, the second blind groove 8, the first through groove 9, the second through groove 10, the metal layer 11, and the third through groove 12 are all on the corresponding plates or layers prepared in advance, and then the first core plate 1, the first non-flowing PP layer 2, the second core plate 3, the second non-flowing PP layer 4, and the third core plate 5 are laminated and combined into one body, and the internal blind groove cavity is formed therein.

[0037] In this way, in the subsequent processing process, cutting can be performed along the first blind groove 7, the second blind groove 8, the first through groove 9, the second through groove 10, and the third through groove 12, so that the part of the metal layer 11 on the right side of the third core plate 5 is removed to obtain the final product. Figure 1

[0038] In the manufacturing process, the first core plate 1, the second core plate 3, and the third core plate 5 are browned, and then the first non-flowing PP layer 2 and the second non-flowing PP layer 4 (non-flowing prepreg) are stacked and riveted by tube position nails, and under the action of temperature and pressure, the resin of the prepreg flows to fill the circuit and the substrate, and when the temperature reaches a certain degree, curing occurs to bond the layers together to form the structure shown in the figure, and the internal blind groove cavity structure is formed at the same time. Figure 1

[0039] In one embodiment, laser cutting is used for cutting to form the first laser cutting groove 13 and the second laser cutting groove 14 to remove the pre-controlled depth remaining thickness.

[0040] Due to the use of the above technical solution, the present application does not need to pre-metalize the edges of all layers, and then perform depth-controlled milling to mill off the excess metalized edges and etch, thereby avoiding the problems of milling depth damage to the metalized edge layer and affecting the unit size quality caused by depth-controlled milling, and mass production can be realized.

[0041] The present application also provides a circuit board local metalized edge processing process, which comprises the following steps:

[0042] Step 1, a first core plate 1, a first non-flowing PP layer 2, a second core plate 3, a second non-flowing PP layer 4, and a third core plate 5 are prepared in advance and arranged from top to bottom, wherein,

[0043] The first core plate 1 and the third core plate 5 comprise the following manufacturing steps 11-13:

[0044] ​​Step 11, Inner Light Imaging 1: At a certain temperature and pressure, a dry film is pasted on the board surface, then aligned with the negative film, and finally irradiated with ultraviolet light on the exposure machine to make the dry film not covered by the negative film react, forming the required circuit pattern on the board surface. Then, through the development section, under the action of the developer, the film not irradiated by light is dissolved, exposing the area to be etched on the first side, and the copper surface on the second side is protected with a dry film;

[0045] Step 12, Inner Layer Etching: In the etching tank, copper reacts with copper ions to produce cuprous copper, achieving the etching effect, manufacturing the circuit on the first side. Then, through the stripping tank, under the action of the alkaline solution, the film is dissolved, exposing the required circuit;

[0046] Step 13, Laser Pre - controlled Deep Cutting: According to the design data, laser pre - controlled deep cutting is carried out from the first side. The width of the pre - controlled deep groove is 0.15 mm, the depth is 0.2 mm, the depth tolerance is ±0.05 mm, and the remaining thickness is guaranteed to be ≥0.15 mm to prevent cutting through, forming a "square - shaped" groove;

[0047] The second core board 3 includes the following manufacturing steps 21 - 26:

[0048] Step 21, Milling Metal Groove Holes with Edge - wrapping: Using a 0.6 - mm milling cutter, milling machine processing is carried out on the board to mill out a long groove at the edge - wrapping position;

[0049] Step 22, Copper Plating on the Board: Using the method of full - board electroplating, the edge - wrapping position and the surface copper are thickened by 5 - 8 μm to connect the edge - wrapping with the copper of the second core board 3;

[0050] Step 23, Outer Light Imaging: At a certain temperature and pressure, a dry film is pasted on the board surface, then aligned with the negative film, and finally irradiated with ultraviolet light on the exposure machine to make the dry film not covered by the negative film react, forming the required circuit pattern on the board surface. Then, through the development section, under the action of the developer, the film not irradiated by light is dissolved, exposing the area to be copper - tin plated;

[0051] Step 24, Pattern Electroplating: A layer of metal copper layer and a tin layer for anti - etching protection are plated on the conductive areas on the board;

[0052] Step 25, Milling Half - Holes: Using a 0.6 - mm milling cutter, milling machine processing is carried out on the board to mill off the positions at both ends that do not require metal edge - wrapping;

[0053] Step 26, Outer Layer Etching: Under the action of the alkaline solution, the film is removed to expose the copper surface to be etched; in the etching tank, copper reacts with copper ions to produce cuprous copper, achieving the etching effect. In the tin - stripping tank, due to the reaction between nitric acid and the tin surface, the tin - plating layer is removed, exposing the circuit pad copper surface;

[0054] Milling machining is performed on the first non-flowable PP layer 2 and the second non-flowable PP layer 4 with a 0.75 mm milling cutter to mill out the first through slot 9 and the third through slot 12 with a width of 0.75 mm;

[0055] Step 2, laminating: the first core plate 1, the second core plate 3, and the third core plate 5 are laminated, then the first non-flowable PP layer 2 and the second non-flowable PP layer 4 are stacked, and the stack is riveted with tube position nails, and then under the action of temperature and pressure, the resin of the prepreg flows to fill the circuit and the substrate, and when the temperature reaches a certain degree, curing occurs to bond the layers together and form the structure of blind slots at the same time;

[0056] Step 3, drilling, copper plating / plate plating, outer light imaging 1, pattern plating, outer layer etching, solder resist / characters are performed on the board formed in step 2;

[0057] In the drilling step, drilling machining is performed on the board according to customer requirements to facilitate the inner and outer layer conduction in the subsequent process;

[0058] In the copper plating / plate plating step, the drill dirt in the hole is removed by the previous deslagging to make the hole clean, and then the surface and the hole are activated to adsorb colloidal palladium, and a redox reaction occurs in the copper plating cylinder to form a copper layer. The hole copper and the surface copper are thickened by 5-8 um using the whole plate plating method, and the hole and the outer layer copper are connected.

[0059] In the outer light imaging 1 step, the dry film is attached to the board surface under certain temperature and pressure, then the film is aligned with the negative, and finally the unshielded dry film of the negative is reacted by ultraviolet light irradiation on the exposure machine to form the required circuit pattern on the board surface. Then, through the development section, the film that is not irradiated by light is dissolved away in the developer, and the area to be plated with copper and tin is exposed.

[0060] In the pattern plating step, the board surface is cleaned through pretreatment, and copper ions and tin ions are dissolved from the anode in the copper plating and tin plating cylinders and move to the cathode under the action of the electric field. The cathode obtains electrons and plating a layer of copper and tin for etching protection on the conductive area on the board.

[0061] In the outer layer etching step, the film is removed to expose the copper surface to be etched under the action of alkali, and the copper reacts with copper ions in the etching cylinder to produce cuprous ions to achieve etching. In the tin stripping cylinder, nitric acid reacts with the tin surface to remove the tin plating layer and expose the circuit pad copper surface.

[0062] In the solder resist / character step, the solder resist is printed on the board surface with a silk screen to form a semi-cured film layer by removing the volatiles through pre-baking. The solder resist film is cross-linked by light exposure, and the unexposed area is developed away in alkali. The solder resist is completely cured at high temperature and adheres to the board surface. The characters are made in a similar way to the solder resist.

[0063] Step 4, laser cutting: laser cutting is performed from the upper and lower surfaces of the plate body formed in step 3, with a groove width of 0.15 mm and a depth tolerance of ±0.05 mm, to cut off the pre-controlled deep remaining thickness.

[0064] Preferably, it further comprises: step 5, gold plating: a layer of metal nickel and gold is deposited on the copper surface through a chemical displacement reaction.

[0065] In the above technical solution, the second core plate 3 with a local layered metallized edge is first made, then it is stacked with the first core plate 1 and the third core plate 5 after laser cutting pre-control deep grooving and the non-flowing PP after grooving, and is pressed to form a blind groove structure, and then it is made through processes such as drilling, copper plating, outer light imaging, outer layer etching, solder mask, character, laser cutting, gold plating, etc. It is not necessary to first make all the layered metallized edges, then control the deep milling, and then etch after milling off the excess layered metallized edges. The problem of milling deep damage to the metallized edge layer and the influence on the unit size quality caused by the control deep milling can be avoided, and mass production can be realized.

[0066] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A process for partial metallization of a circuit board edge, characterized in that, It includes the following steps: Step 1: Pre-manufacture a first core board (1), a first non-flowable PP layer (2), a second core board (3), a second non-flowable PP layer (4), and a third core board (5) which are arranged successively from top to bottom. Among them, The first core board (1) and the third core board (5) include the following manufacturing steps 11-13: Step 11: Inner light imaging: At a certain temperature and pressure, stick a dry film on the board surface, then align it with a negative film, and finally use ultraviolet light irradiation on an exposure machine to make the dry film not covered by the negative film react, forming the required circuit pattern on the board surface. Then, through the developing section, under the action of the developing solution, dissolve the film not irradiated by light, expose the area to be etched on the first side, and protect the copper surface on the second side with a dry film; Step 12: Inner layer etching: React copper with copper ions in an etching tank to produce cuprous copper to achieve the etching effect, manufacture the circuit on the first side, and then dissolve the film in a stripping tank under the action of an alkaline solution to expose the required circuit; Step 13: Laser pre-controlled deep cutting: Perform laser pre-controlled deep cutting from the first side according to the design data. The pre-controlled groove width is 0.15 mm, the depth is 0.2 mm, the depth tolerance is ±0.05 mm, and the remaining thickness is guaranteed to be ≥0.15 mm to prevent cutting through, forming a "square frame" - shaped groove; The second core board (3) includes the following manufacturing steps 21-26: Step 21: Milling metal slot holes: Use a 0.6 mm milling cutter to perform milling machine processing on the board, and mill out a long slot at the edge position; Step 22: Copper deposition and board plating: Use the method of full-board electroplating to thicken the edge position and surface copper by 5-8 μm, and connect the edge to the copper of the second core board (3); Step 23: Outer light imaging: At a certain temperature and pressure, stick a dry film on the board surface, then align it with a negative film, and finally use ultraviolet light irradiation on an exposure machine to make the dry film not covered by the negative film react, forming the required circuit pattern on the board surface. Then, through the developing section, under the action of the developing solution, dissolve the film not irradiated by light, and expose the area to be copper-tin plated; Step 24: Pattern electroplating: Deposit a layer of metal copper layer and a tin layer for anti-etching protection on the conductive area of the board; Step 25: Milling half holes: Use a 0.6 mm milling cutter to perform milling machine processing on the board, and mill off the positions at both ends that do not require metal edge protection; Step 26: Outer layer etching: Under the action of an alkaline solution, remove the film to expose the copper surface to be etched. React copper with copper ions in an etching tank to produce cuprous copper to achieve the etching effect. In a tin stripping tank, react nitric acid with the tin surface to remove the tin plating layer and expose the circuit pad copper surface; Use a 0.75 mm milling cutter to perform milling machine processing on the first non-flowable PP layer (2) and the second non-flowable PP layer (4), and mill out a first through groove (9) and a third through groove (12) with a width of 0.75 mm; Step 2, laminating: laminating the first core plate (1), the second core plate (3), and the third core plate (5) to form a core plate brown, then through the first non-flowing PP layer (2), the second non-flowing PP layer (4) are stacked, and the tube is riveted together. Under the action of temperature and pressure, the resin of the prepreg flows to fill the circuit and the substrate. When the temperature reaches a certain degree, curing occurs to bond the layers together and form a blind slot structure at the same time. Step 3, drilling, copper plating, plate plating, outer light imaging, pattern plating, outer layer etching, solder mask, and characters are performed on the plate body formed in step 2. Step 4, laser cutting: laser cutting is performed from the upper and lower surfaces of the plate body formed in step 3, with a slot width of 0.15mm and a depth tolerance of ±0.05mm. The remaining thickness is cut off by pre-control depth.

2. The partial metallization edging process of claim 1, wherein, Also includes: Step 5: gold plating: a layer of metal nickel and gold is deposited on the copper surface through a chemical displacement reaction.

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