CN116723635A - Preparation method of circuit board capable of preventing white edges and high-TG circuit board - Google Patents
Preparation method of circuit board capable of preventing white edges and high-TG circuit board Download PDFInfo
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- CN116723635A CN116723635A CN202310710351.0A CN202310710351A CN116723635A CN 116723635 A CN116723635 A CN 116723635A CN 202310710351 A CN202310710351 A CN 202310710351A CN 116723635 A CN116723635 A CN 116723635A
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- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- 238000003801 milling Methods 0.000 claims abstract description 416
- 239000000758 substrate Substances 0.000 claims abstract description 160
- 229910000679 solder Inorganic materials 0.000 claims abstract description 37
- 238000003466 welding Methods 0.000 claims abstract description 28
- 238000005553 drilling Methods 0.000 claims abstract description 12
- 238000001465 metallisation Methods 0.000 claims abstract description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 30
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Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/0011—Working of insulating substrates or insulating layers
- H05K3/0044—Mechanical working of the substrate, e.g. drilling or punching
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
- H05K2203/02—Details related to mechanical or acoustic processing, e.g. drilling, punching, cutting, using ultrasound
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Milling Processes (AREA)
Abstract
The application provides a preparation method of a circuit board capable of preventing white edges and a high-TG circuit board. The preparation method of the circuit board for preventing the white edge comprises the steps of drilling a base plate so that a through hole is formed in the base plate; carrying out metallization treatment on the substrate so as to metalize the via hole; performing solder resist treatment on the substrate to form a solder resist layer and a plurality of bonding pads on the surface of the substrate; forming the substrate, and milling positioning clamping grooves in the solder masks of two adjacent bonding pads through a milling cutter, wherein the positioning clamping grooves are used for carrying out SMT positioning on electronic elements; the welding-resistant layers of the adjacent two welding-resistant layers are provided with a pre-milling area and a finish-milling area, the milling cutter is used for carrying out first milling on the pre-milling area, so that a gap is formed between a plate in the pre-milling area and a plate in the finish-milling area, the resistance of the milling cutter when the milling cutter is used for milling in the finish-milling area is reduced, and the milling cutter is used for carrying out second milling on the finish-milling area so as to form the positioning clamping groove.
Description
Technical Field
The application relates to the field of circuit board manufacturing, in particular to a method for preparing a circuit board capable of preventing white edges.
Background
Along with the instantaneous change of the development of electronic products, the requirements of people on the design concept of miniaturization of the electronic products are more and more strict, and the requirements on the dimensional stability of graphic design are more strict, so that the difficulty of designing and manufacturing a circuit board is greatly increased. The smaller the size of the circuit board unit, the larger the thickness, and the greater the difficulty of mechanical forming processing, and various adverse problems are caused. When milling a board in a forming process aiming at a high TG (material with a glass transition temperature of more than 170 degrees under high-temperature heating) and a halogen-free board, when the acting force of the milling cutter on the board is larger than the binding force of the board, the local resin of the board is separated from glass fibers to form a white edge as shown in fig. 1, and the white edge at the position of an adjacent bonding pad can influence the voltage of the circuit board, so that the performance of the circuit board is influenced.
Therefore, there is a need to improve the board milling process of the circuit board, so as to avoid the occurrence of white edges during board milling, and further improve the product yield of the circuit board.
Disclosure of Invention
The application aims to overcome the defects in the prior art and provides a method for preparing a circuit board with white edge prevention, which is used for avoiding white edge generated during board milling of the circuit board and improving the yield of the circuit board product.
The aim of the application is realized by the following technical scheme:
a preparation method of a circuit board capable of preventing white edges comprises the following steps:
drilling the substrate so that a via hole is formed in the substrate;
carrying out metallization treatment on the substrate, and placing the substrate in a liquid medicine tank so as to metalize the through holes;
performing solder resist treatment on the substrate to form a solder resist layer and a plurality of bonding pads on the surface of the substrate;
forming the substrate, and milling positioning clamping grooves in the solder masks of two adjacent bonding pads through a milling cutter, wherein the positioning clamping grooves are used for carrying out SMT positioning on electronic elements;
the welding-resistant layers of the adjacent two welding-resistant layers are provided with a pre-milling area and a finish-milling area, the milling cutter is used for carrying out first milling on the pre-milling area, so that a gap is formed between a plate in the pre-milling area and a plate in the finish-milling area, the resistance of the milling cutter when the milling cutter is used for milling in the finish-milling area is reduced, and the milling cutter is used for carrying out second milling on the finish-milling area so as to form the positioning clamping groove.
In one embodiment, the linear distance between the pre-milling area boundary and the finish-milling area boundary is 0.2mm-0.3mm.
In one embodiment, the pre-milling zone is located within the finish milling zone.
In one embodiment, before the step of routing the pre-milled area for the first time, the method for manufacturing a circuit board for preventing white edges further includes the following steps:
calculating the routing travel of the milling cutter so that the milling cutter stops being used before the residual service life is 200 cm;
and controlling the speed of the milling cutter so as to ensure that the speed of the milling cutter is 1m/min-1.8m/min.
In one embodiment, before the step of routing the finish milling area for the second time, the method for manufacturing the circuit board for preventing white edges further includes the following steps:
calculating the routing travel of the milling cutter so that the milling cutter stops being used before the residual service life is 400 cm;
and controlling the speed of the milling cutter so as to ensure that the speed of the milling cutter is between 0.8m/min and 1.6m/min.
In one embodiment, performing a solder resist process on the substrate to form a solder resist layer and a plurality of pads on a surface of the substrate includes the steps of:
coating an insulating agent on the surface of the substrate;
exposing the insulating agent in the partial area of the substrate surface to enable the insulating agent to be solidified on the substrate surface to form a solder mask;
and cleaning the unexposed insulating agent on the substrate surface to form a bonding pad on the substrate surface.
In one embodiment, before the step of drilling the substrate to form the via hole on the substrate, the method for manufacturing a circuit board for preventing white edges further includes the steps of:
carrying out a cutting operation on the base material to form the substrate;
and performing inner layer etching on the substrate to form a circuit layer on the surface of the substrate.
In one embodiment, the substrate is a halogen-free material.
In one embodiment, the step of metallizing the substrate and placing the substrate in a chemical tank to metallize the via hole comprises:
carrying out electroless copper plating operation on the substrate so as to form a copper layer in the through hole of the substrate;
and carrying out copper electroplating operation on the substrate so as to thicken the copper layer of the via hole.
The application also provides a circuit board prepared by adopting the preparation method of the circuit board for preventing white edges.
Compared with the prior art, the application has at least the following advantages:
according to the circuit board preparation method for preventing the white edges, when the substrate is subjected to forming treatment, namely, the welding layers of the adjacent two welding pads are subjected to milling to form the positioning clamping groove, the pre-milling area and the finish milling area are preset in the welding layers of the adjacent two welding pads, the milling cutter is subjected to milling for the first time in the pre-milling area, so that a gap is formed between a board in the pre-milling area and the board in the finish milling area, and the milling cutter is subjected to milling for the second time to form the positioning clamping groove, at the moment, because the gap exists between the finish milling area and the board in the pre-milling area, namely, the binding force between the board in the pre-milling area and the board in the finish milling area is reduced, the resistance of the milling cutter in the finish milling area is reduced, the white edges of the substrate outside the finish milling area are avoided, and the product yield of the circuit board is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a physical diagram of a circuit board with a white edge formed by the prior art;
FIG. 2 is a schematic diagram of a circuit board according to an embodiment;
FIG. 3 is a schematic flow chart of a method for manufacturing a circuit board with anti-white edges according to an embodiment;
fig. 4 is a physical view of a circuit board without white edges prepared by the process shown in fig. 3.
Detailed Description
In order that the application may be readily understood, a more complete description of the application will be rendered by reference to the appended drawings. The drawings illustrate preferred embodiments of the application. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
The application provides a preparation method of a circuit board capable of preventing white edges, which comprises the steps of drilling a base plate so that a through hole is formed in the base plate; carrying out metallization treatment on the substrate, and placing the substrate in a liquid medicine tank so as to metalize the through holes; performing solder resist treatment on the substrate to form a solder resist layer and a plurality of bonding pads on the surface of the substrate; forming the substrate, and milling positioning clamping grooves in the solder masks of two adjacent bonding pads through a milling cutter, wherein the positioning clamping grooves are used for carrying out SMT positioning on electronic elements; the welding-resistant layers of the adjacent two welding-resistant layers are provided with a pre-milling area and a finish-milling area, the milling cutter is used for carrying out first milling on the pre-milling area, so that a gap is formed between a plate in the pre-milling area and a plate in the finish-milling area, the resistance of the milling cutter when the milling cutter is used for milling in the finish-milling area is reduced, and the milling cutter is used for carrying out second milling on the finish-milling area so as to form the positioning clamping groove.
According to the circuit board preparation method for preventing the white edges, when the substrate is subjected to forming treatment, namely, the welding layers of the adjacent two welding pads are subjected to milling to form the positioning clamping groove, the pre-milling area and the finish milling area are preset in the welding layers of the adjacent two welding pads, the milling cutter is subjected to milling for the first time in the pre-milling area, so that a gap is formed between a board in the pre-milling area and the board in the finish milling area, and the milling cutter is subjected to milling for the second time to form the positioning clamping groove, at the moment, because the gap exists between the finish milling area and the board in the pre-milling area, namely, the binding force between the board in the pre-milling area and the board in the finish milling area is reduced, the resistance of the milling cutter in the finish milling area is reduced, the white edges of the substrate outside the finish milling area are avoided, and the product yield of the circuit board is improved.
In order to better understand the technical scheme and beneficial effects of the present application, the following describes the present application in further detail with reference to specific embodiments:
as shown in fig. 2 and 3, the method for manufacturing a circuit board with white edge prevention according to an embodiment includes the following steps:
s101, drilling operation is carried out on the substrate so that a through hole is formed on the substrate.
In this embodiment, the drilling operation is performed on the substrate by the drilling machine, that is, the drill bit on the drilling machine penetrates through the substrate, so that the substrate is formed with the via hole.
S103, carrying out metallization treatment on the substrate;
in this embodiment, the substrate is placed in a liquid medicine tank containing copper ions, and the copper ions lose electrons in the via holes to generate copper simple substances, so that a copper layer is formed in the via holes. Further, the copper layer in the through hole is communicated with the upper layer circuit and the lower layer circuit of the substrate, so that the circuit board is conducted.
S105, performing a solder resist treatment on the substrate so as to form a solder resist layer and a plurality of bonding pads on the surface of the substrate;
in this embodiment, the substrate is subjected to a solder resist treatment, that is, by coating a layer of insulating solder resist on the surface of the substrate, the insulating solder resist covered on the surface of the substrate is exposed to light for the surface to be insulated, so that the insulating solder resist is cured on the surface to play a role in insulation protection. And cleaning the insulating solder resist on the board to be soldered to form a bonding pad.
S107, performing molding treatment on the substrate, and milling positioning clamping grooves in the solder masks of two adjacent bonding pads through a milling cutter, wherein the positioning clamping grooves are used for performing SMT positioning on the electronic element;
it can be understood that the whole substrate contains a plurality of bonding pads, the rest positions of the bonding pads are covered by the solder mask, and a positioning clamping groove is required to be formed at the solder mask position of the adjacent bonding pads for SMT positioning of the electronic component, and the electronic component can be the internal resistance of the capacitor, so that a complete circuit layer is formed on the surface of the substrate. In this embodiment, the substrate is milled by using a milling machine, and parameters of the milling machine are adjusted before milling, such as a feeding speed of the milling cutter and a pressure value of the milling cutter on the substrate, so that a positioning slot meeting requirements is formed on the substrate. Further, SMT positioning refers to an electronic assembly technique that uses specialized automated equipment such as a chip mounter, a printer, etc. to directly attach and solder surface electronic components (such as resistors, capacitors, inductors, etc.) to the surface of a circuit board.
The welding-resistant layers of the adjacent two welding-resistant layers are provided with a pre-milling area and a finish-milling area, the milling cutter is used for carrying out first milling on the pre-milling area, so that a gap is formed between a plate in the pre-milling area and a plate in the finish-milling area, the resistance of the milling cutter when the milling cutter is used for milling in the finish-milling area is reduced, and the milling cutter is used for carrying out second milling on the finish-milling area so as to form the positioning clamping groove.
In this embodiment, a pre-milling area and a finish-milling area are provided in the solder resist of two adjacent bonding pads, and the milling cutter performs first milling on the pre-milling area, so that a gap is formed between the substrate plate in the pre-milling area and the substrate plate in the finish-milling area. After finishing the milling of the pre-milling area, carrying out secondary milling on the baseplate of the finish milling area, wherein at the moment, because a gap is formed between the baseplate of the pre-milling area and the baseplate of the finish milling area, namely, the binding force between the baseplate of the pre-milling area and the baseplate of the finish milling area is reduced, when the finish milling area carries out secondary milling, the stretching force of the baseplate of the pre-milling area to the baseplate of the finish milling area is negligible, namely, the baseplate of the finish milling area only receives the binding force of the baseplate of the finish milling area except the pre-milling area to the baseplate of the finish milling area, thereby reducing the friction resistance of the milling cutter during the milling of the finish milling area, and avoiding the generation of white edges during the milling of the finish milling area.
For example, as shown in fig. 2, in one embodiment, a square positioning slot with a specification of 20mm x 20mm needs to be milled between two adjacent bonding pads 100, so that a pre-milling area 200 and a finish milling area 300 are preset between two adjacent bonding pads 100 before milling, and when milling is performed for the first time in the pre-milling area 200, a square positioning slot with a specification of 19mm x 19mm is milled, and at this time, a gap is formed between the substrate board of the pre-milling area 200 and the substrate board of the finish milling area 300. Then, the finish milling area 300 is milled for the second time, 20mm square positioning clamping grooves are milled, namely, the square positioning clamping grooves with the required specification are milled for the second time, at the moment, the substrate plates of the finish milling area 300 are only subjected to the binding force of the substrate plates outside the pre-milling area 200, the friction resistance of the milling cutter is reduced during milling of the finish milling area 300, namely, the milling cutter can mill the positioning clamping grooves by applying small mechanical external force to the substrate plates of the finish milling area 300, and white edges are avoided during milling of the finish milling area 300.
According to the circuit board preparation method for preventing white edges, when the substrate is subjected to forming treatment, namely, the welding layers of the adjacent two welding pads are subjected to milling to form the positioning clamping groove, the pre-milling area and the finish milling area are preset in the welding layers of the adjacent two welding pads, the milling cutter is subjected to milling for the first time in the pre-milling area, so that a gap is formed between a board in the pre-milling area and a board in the finish milling area, and the milling cutter is subjected to milling for the second time to form the positioning clamping groove, and at the moment, due to the gap between the finish milling area and the board in the pre-milling area, the binding force between the board in the pre-milling area and the board in the finish milling area is reduced, so that the resistance of the milling cutter in the finish milling area is reduced, the white edges in the positioning clamping groove are avoided, and the product yield of the circuit board is improved.
In one embodiment, the linear distance between the pre-milling area boundary and the finish-milling area boundary is 0.2mm-0.3mm. It can be appreciated that the circuit board tends to be miniaturized in design, be provided with between two adjacent bonding pads and mill district and finish milling district, and the distance of mill district and finish milling district in advance is 0.2mm-0.3mm, and clearance area between mill district and the finish milling district in advance is less promptly, and when the finish milling district carries out the gong board, the sheet bonding force of the sheet in the clearance to the sheet of finish milling district is less, and the frictional resistance that the milling cutter received when the finish milling district carries out the gong board is less like this, has avoided the formation of the white limit in the positioning card groove of finish milling district.
In one embodiment, as shown in fig. 2, the pre-milling zone is located within the finish-milling zone. In this embodiment, a pre-milling area and a finish milling area are preset between two adjacent bonding pads, the pre-milling area is located in the finish milling area, when the milling cutter is used for milling a substrate, first milling is performed in the pre-milling area, a positioning clamping groove with a smaller area can be milled in the pre-milling area according to the shape of the positioning clamping groove to be milled, then second milling is performed in the finish milling area, the second milling is the positioning clamping groove meeting the specification requirement, so that the friction resistance suffered by the milling cutter is smaller when the second milling is performed in the finish milling area, and the formation of white edges on the surface of the circuit board is avoided.
In one embodiment, before the step of routing the pre-milled area for the first time, the method for manufacturing a circuit board further includes the steps of:
firstly, calculating the routing travel of the milling cutter, namely controlling the service life of the routing cutter, so that the milling cutter is stopped to be used before the rest service life is 200 cm;
it can be understood that the milling cutter can be passivated after a certain travel of feed, if the passivated milling cutter substrate is used for milling, the friction resistance born by the substrate is larger, white edges are easy to generate on the surface of the substrate, and therefore the service life of the milling cutter is required to be controlled before milling, namely, the milling cutter is used for milling the substrate before passivation. Further, the service life of a general milling cutter is about 20m, when the milling stroke of the milling cutter reaches 20m, the milling cutter can be passivated, so when the milling cutter is milled for the first time in the pre-milling area, the service life of the milling cutter mechanical equipment is required to be controlled, namely, when the milling stroke of the milling cutter reaches 18m in the normal range of 20m, the milling cutter mechanical equipment stops operating, and at the moment, a new milling cutter is replaced to mill, so that the friction resistance generated by the milling cutter during milling is smaller, the occurrence of white edges of a substrate is avoided, and the replaced milling cutter can be reused in the circuit board processing equipment with lower processing requirements.
Secondly, controlling the speed of the first milling in the pre-milling area so as to enable the speed of the milling cutter to be 1m/min-1.8m/min.
Further, the step of calculating the routing travel of the milling cutter includes: firstly, obtaining the product delivery number of the current milling cutter; then, the data of the milling depth of the current milling cutter is corresponding to the factory number of the product; then, acquiring and accumulating the data of the milling depth of the current milling cutter in real time to obtain the accumulated machining milling range of the current milling cutter; then judging whether the accumulated machining milling stroke of the current milling cutter is smaller than a preset value which is 18m; if yes, the milling cutter is not replaced; if not, stopping and replacing the current milling cutter, realizing real-time monitoring of the accumulated machining milling process of the current milling cutter, reducing the problems of manual statistics errors or larger deviation, and ensuring the machining quality of the circuit board. Further, whether the frequency of the accumulated machining gong of the current milling cutter is smaller than the preset value is 0.1 s-0.2 s is judged, so that statistics of the accumulated machining gong of the current milling cutter can be confirmed in time, whether a cutter needs to be replaced or not is judged quickly, and the machining reliability of the current milling cutter is improved. It should be noted that, the product factory number of the current milling cutter can be directly formed on the surface of the milling cutter during manufacturing.
It can be understood that the feeding speed of the milling cutter also affects the friction force between the milling cutter and the substrate, the feeding speed of the milling cutter is higher, the mechanical pressure of the milling cutter to the substrate is higher, white edges are easy to generate during milling, so that the feeding speed of the milling cutter needs to be controlled, and the production efficiency is improved as much as possible while the white edges are avoided.
In one embodiment, before the step of routing the finish milling area for the second time, the method for manufacturing a circuit board further includes the following steps:
firstly, calculating the routing travel of the milling cutter, namely controlling the service life of the routing cutter, so that the milling cutter is stopped to be used before the residual service life is 400 cm;
it can be understood that the milling cutter can be passivated after a certain travel of feed, if the passivated milling cutter substrate is used for milling, the friction resistance born by the substrate is larger, white edges are easy to generate on the surface of the substrate, and therefore the service life of the milling cutter is required to be controlled before milling, namely, the milling cutter is used for milling the substrate before passivation. Further, the service life of a general milling cutter is about 20m, when the milling stroke of the milling cutter reaches 20m, the milling cutter can be passivated, so that when the milling cutter is milled for the second time in the finish milling area, the service life of the milling cutter mechanical equipment is required to be controlled, and the positioning clamping groove milled in the finish milling area is required to be more strict so as to prevent the positioning clamping groove milled in the finish milling area from generating white edges, namely, when the milling stroke of the milling cutter reaches 16m in the normal range of 20m, the milling cutter mechanical equipment stops operating, and at the moment, a new milling cutter is replaced to carry out milling, so that the friction resistance generated by the milling cutter during milling is smaller, the white edges of a substrate are avoided, and the replaced milling cutter can be repeatedly used in the circuit board processing equipment with lower processing requirements.
Secondly, the milling cutter is subjected to speed control so that the speed of the milling cutter is between 0.8m/min and 1.6m/min.
It can be understood that the feeding speed of the milling cutter also affects the friction force between the milling cutter and the substrate, the feeding speed of the milling cutter is higher, the mechanical pressure of the milling cutter to the substrate is higher, white edges are easy to generate during milling, so that the feeding speed of the milling cutter needs to be controlled, and the production efficiency is improved as much as possible while the white edges are avoided. And the milling in the finish milling area is required to be stricter, so that the blank is formed in the positioning clamping groove milled in the finish milling area, and the product yield of the circuit board is improved.
In one embodiment, the step of performing a solder resist process on the substrate includes the steps of:
first, an insulating agent, in this embodiment, an ink, is applied to the surface of the substrate. It can be appreciated that the ink has an insulating effect and is low in production cost, so that the ink is generally coated on the surface of the substrate to play a role in insulating protection.
And exposing the insulating agent in the partial area of the substrate surface to enable the insulating agent to be solidified on the substrate surface to form a solder mask.
It will be appreciated that the ink covers the lines and copper surfaces that do not require soldering, and serves to protect the lines and insulation, i.e., the ink is photopolymerized after passing through the exposure, i.e., the ink solidifies on the lines and barrels that do not require soldering, forming a solder mask.
And finally, cleaning the unexposed insulating agent on the substrate surface to form a bonding pad on the substrate surface. It will be appreciated that depending on the acid and alkali resistant properties of the ink, the unexposed ink is rinsed off with an alkaline liquid, leaving the areas of the board surface to be soldered exposed to form pads.
In one embodiment, before the step of drilling the substrate, the method for manufacturing a circuit board for preventing white edges further includes the steps of:
firstly, carrying out a material cutting operation on a base material to form the substrate;
it can be understood that the large-area base material is cut to form the base plate with corresponding size, and the included angle of the base plate is rounded after the material is cut, namely, some cotton, cotton cloth or rubber is used for wrapping the included angle of the base plate, so that the plate surface is prevented from being rubbed in the production process of the subsequent procedure.
And secondly, carrying out inner layer etching on the substrate so as to form a circuit layer on the surface of the substrate.
In this embodiment, the inner layer etching operation includes inner layer wet film, developing negative film and exposure developing. Firstly, removing oxide on the surface of a substrate by utilizing microetching action of sulfuric acid, and roughening the surface of the substrate to enhance the adhesive force of the surface of the substrate, so that the ink can be conveniently and tightly adhered on the surface of the substrate; secondly, manufacturing a film developing negative through a pre-designed circuit diagram, then pasting a layer of photosensitive wet film on the surface of a substrate, and then changing the surface ink from a monomer to a polymer through ultraviolet irradiation to realize pattern transfer; finally, all copper surfaces except the circuit patterns are completely eroded through the liquid medicine, and the required patterns are etched.
In one embodiment, the substrate is a halogen-free material. It can be understood that, in order to achieve the environmental protection requirement, the circuit board substrate is generally made of halogen-free and high TG materials, wherein halogen-free refers to halogen elements such as fluorine, chlorine, bromine and iodine which do not include or exceed a certain content, high TG refers to materials with a glass transition temperature of more than 170 degrees under high temperature heating, and the circuit board made of the materials has the characteristics of environmental protection, high temperature resistance, strong impact resistance and the like, but has higher brittleness, and is easy to generate white spots or white edges during routing, so that a higher standard and practical process is required during the forming treatment of the circuit board.
In one embodiment, the step of metallizing the substrate and placing the substrate in a chemical tank to metallize the via hole comprises:
firstly, carrying out electroless copper plating operation on the substrate so as to form a copper layer in a via hole of the substrate;
and secondly, carrying out copper electroplating operation on the substrate so as to thicken the copper layer of the via hole.
In this embodiment, the substrate is placed in a liquid chemical tank to perform electroless copper deposition, the liquid chemical tank contains a liquid chemical with copper ions, the copper ions lose electrons on the hole wall of the via hole to generate a copper simple substance, and the copper simple substance is attached to the hole wall to form a copper layer. It will be appreciated that copper layers formed by electroless copper deposition are relatively thin and relatively low in hardness, and thus require thickening of the copper layers to increase the structural strength of the copper layers. Therefore, the electric conduction is carried out in the liquid medicine tank, and more copper ions form copper simple substance under the action of the electric conduction energy, so that the thickness of the copper layer on the through hole is higher. Namely, under the combined action of the electroless copper plating operation and the electrolytic copper plating operation, the copper layer of the via hole has higher hardness and thickness, so that the via hole has better conducting function.
It can be understood that at routing in-process milling cutter and base plate contact, and milling cutter is continuous the feed routing on the base plate, consequently continuous friction between milling cutter and the base plate for the temperature of milling cutter is continuous rising at routing in-process, when the temperature reaches 400 ℃, and high temperature makes milling cutter soften, and the cutting ability of milling cutter weakens like this, makes milling cutter equipment need apply bigger mechanical pressure to milling cutter to the base plate routing, and then causes the easy condition that produces the blank of base plate. In order to solve the above problem, in one embodiment, a sectional type milling operation is adopted, that is, when a substrate is subjected to milling operation, after a milling cutter is subjected to preset milling, the milling cutter is controlled to stop milling, at the moment, the milling cutter is controlled to ascend and horizontally move to the position above the other substrate on a milling belt, which is required to be milled, then the milling cutter is controlled to descend and mill the other substrate, in the whole milling operation process, the milling cutter plays a cooling effect in the ascending, horizontally moving and descending processes, and meanwhile, the milling cutter is prevented from rising in the continuous milling process temperature, so that the milling cutter is softened. For example, after a square positioning clamping groove is milled between two adjacent bonding pads on one substrate, the milling cutter is controlled to ascend and horizontally move to the position above the other substrate on the milling belt, and then the milling cutter is controlled to descend and mill the other substrate; after a square positioning clamping groove is formed between two adjacent bonding pads of the other substrate by the control milling cutter, the control milling cutter sequentially ascends, horizontally moves and descends to return to the first substrate, and the rest positions of the first substrate are subjected to milling. Through the operation of the assembly line, the temperature of the milling cutter is effectively reduced in the processes of rising, horizontally moving and falling, and the milling cutter is prevented from softening due to the rising of the temperature in the continuous operation of the milling cutter. Specifically, the feed stroke value and the moving distance of the milling cutter can be set through a program, so that the milling precision problem of the milling cutter on different substrates in assembly line operation is guaranteed, white edges of the substrates are prevented from being generated during milling, and meanwhile, the production efficiency is improved.
However, when the temperature of the milling cutter cannot be lowered after a long period of operation, the milling cutter is softened by a high temperature. In order to avoid the problem that the milling cutter is softened due to high temperature, further, after the step of milling the first substrate by the milling cutter, the method for preparing the circuit board for preventing white edges further comprises the following steps: before the milling cutter is controlled to move to the second substrate for milling, spraying cooling liquid on the surface of the milling cutter, and performing physical cooling on the milling cutter through spraying the cooling liquid on the surface of the milling cutter, so that the effect of rapidly cooling the milling cutter is realized; because the surface of the milling cutter is very high at this time, after alcohol is sprayed to the surface of the milling cutter, the alcohol volatilizes rapidly and takes away heat on the surface of the milling cutter, so that the temperature of the surface of the milling cutter drops rapidly, the problem that the milling cutter is softened due to high temperature is further prevented, and the problem of white edges generated when the milling cutter plates a substrate is avoided. In this embodiment, the cooling liquid may be alcohol.
However, after spraying the cooling liquid on the surface of the milling cutter, part of the cooling liquid can be sprayed on the surface of the substrate, and as the milling cutter is used for milling the substrate, the solder mask layer and part of materials on the surface of the substrate can be adhered on the surface of the substrate along with the milling of the milling cutter, so that the quality of the circuit board is reduced. In order to improve the quality of the circuit board, in one embodiment, the substrate after routing is placed in a water tank for cleaning so as to remove the cooling liquid on the surface of the substrate. Further, a stirring device is arranged in the water tank, so that cleaning liquid of the water tank flows vigorously to better wash away the substrate, so that the cooling liquid on the surface of the substrate and materials after routing are washed away, and finally, the substrate after the board washing is placed in an oven for drying treatment, and moisture on the surface of the substrate is dried, so that all operations of routing are completed. In this embodiment, the cleaning liquid of the water tank is cleaning water or other cleaning agents. Still further, agitating unit includes driving piece and (mixing) shaft, and the driving piece is installed on the cell wall of basin, and the (mixing) shaft is located the basin, and the driving piece drives the (mixing) shaft and rotates for the cleaning liquid of basin flows violently. It will be appreciated that the driving member is a cylinder or a motor.
The application also provides a circuit board prepared by adopting the preparation method of the circuit board for preventing white edges.
As shown in fig. 4, in this embodiment, a drilling operation is performed on a substrate first, so that a via hole is formed on the substrate, that is, the via hole is formed through the substrate by a drill; secondly, carrying out metallization treatment on the substrate, and placing the substrate in a liquid medicine tank so as to metalize the through holes; then, performing a solder resist treatment on the substrate to form a solder resist layer and a plurality of bonding pads on the surface of the substrate; and finally, carrying out forming treatment on the substrate, and routing a positioning clamping groove in the solder masks of two adjacent bonding pads through a milling cutter, wherein the positioning clamping groove is used for positioning and clamping the electronic element. The welding-resistant layers of the adjacent two welding-resistant layers are provided with a pre-milling area and a finish-milling area, the milling cutter is used for carrying out first milling on the pre-milling area, so that a gap is formed between a plate in the pre-milling area and a plate in the finish-milling area, the resistance of the milling cutter when the milling cutter is used for milling in the finish-milling area is reduced, and the milling cutter is used for carrying out second milling on the finish-milling area so as to form the positioning clamping groove. The circuit board is subjected to routing through the process, so that white edges can be effectively avoided.
Compared with the prior art, the application has at least the following advantages:
according to the circuit board preparation method for preventing white edges, when the substrate is subjected to forming treatment, namely, the welding layers of two adjacent welding pads are subjected to milling to form the positioning clamping groove, the pre-milling area and the finish milling area are preset in the welding layers of two adjacent welding pads, the milling cutter is subjected to milling for the first time in the pre-milling area, so that a gap is formed between a board in the pre-milling area and a board in the finish milling area, the milling cutter is subjected to milling for the second time in the finish milling area to form the positioning clamping groove, and at the moment, due to the gap between the finish milling area and the board in the pre-milling area, the binding force between the board in the pre-milling area and the board in the finish milling area is reduced, so that the resistance to the milling of the board in the finish milling area is reduced, the white edges in the positioning clamping groove are avoided, and the product yield of the circuit board is improved.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.
Claims (10)
1. The preparation method of the circuit board capable of preventing white edges is characterized by comprising the following steps of:
drilling the substrate so that a via hole is formed in the substrate;
carrying out metallization treatment on the substrate;
performing solder resist treatment on the substrate to form a solder resist layer and a plurality of bonding pads on the surface of the substrate;
forming the substrate, and milling positioning clamping grooves in the solder masks of two adjacent bonding pads through a milling cutter, wherein the positioning clamping grooves are used for carrying out SMT positioning on electronic elements;
the welding-resistant layers of the adjacent two welding-resistant layers are provided with a pre-milling area and a finish-milling area, the milling cutter is used for carrying out first milling on the pre-milling area, so that a gap is formed between a plate in the pre-milling area and a plate in the finish-milling area, the resistance of the milling cutter when the milling cutter is used for milling in the finish-milling area is reduced, and the milling cutter is used for carrying out second milling on the finish-milling area so as to form the positioning clamping groove.
2. The method of manufacturing a circuit board with anti-white-edge according to claim 1, wherein a linear distance between the pre-milling area boundary and the finish-milling area boundary is 0.2mm to 0.3mm.
3. The method of claim 1, wherein the pre-milling area is located within the finish milling area.
4. The method of manufacturing a circuit board for preventing white edges according to claim 1, wherein before the step of routing the pre-milled area for the first time, the method further comprises the steps of:
calculating the routing travel of the milling cutter so that the milling cutter stops being used before the residual service life is 200 cm;
and controlling the speed of the milling cutter so as to ensure that the speed of the milling cutter is 1m/min-1.8m/min.
5. The method of manufacturing a circuit board for preventing white edges according to claim 1, wherein before the step of routing the finish milling area for the second time, the method further comprises the steps of:
calculating the routing travel of the milling cutter so that the milling cutter stops being used before the residual service life is 400 cm;
and controlling the speed of the milling cutter so as to ensure that the speed of the milling cutter is between 0.8m/min and 1.6m/min.
6. The method of manufacturing a circuit board with white edge prevention according to claim 1, wherein performing a solder resist treatment on the substrate so that a solder resist layer and a plurality of pads are formed on a surface of the substrate comprises the steps of:
coating an insulating agent on the surface of the substrate;
exposing the insulating agent in the partial area of the substrate surface to enable the insulating agent to be solidified on the substrate surface to form a solder mask;
and cleaning the unexposed insulating agent on the substrate surface to form a bonding pad on the substrate surface.
7. The method of manufacturing a circuit board against white edges according to claim 1, wherein before the step of drilling the substrate to form the substrate with the via holes, the method further comprises the steps of:
carrying out a cutting operation on the base material to form the substrate;
and performing inner layer etching on the substrate to form a circuit layer on the surface of the substrate.
8. The method of manufacturing a circuit board with anti-white edge according to claim 7, wherein the base material is a halogen-free material.
9. The method of manufacturing a circuit board with white edge prevention according to claim 1, wherein the step of metallizing the substrate and placing the substrate in a bath to metallize the via hole comprises:
carrying out electroless copper plating operation on the substrate so as to form a copper layer in the through hole of the substrate;
and carrying out copper electroplating operation on the substrate so as to thicken the copper layer of the via hole.
10. A circuit board manufactured by the method for manufacturing a white edge-preventing circuit board according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310710351.0A CN116723635A (en) | 2023-06-14 | 2023-06-14 | Preparation method of circuit board capable of preventing white edges and high-TG circuit board |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310710351.0A CN116723635A (en) | 2023-06-14 | 2023-06-14 | Preparation method of circuit board capable of preventing white edges and high-TG circuit board |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116723635A true CN116723635A (en) | 2023-09-08 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310710351.0A Pending CN116723635A (en) | 2023-06-14 | 2023-06-14 | Preparation method of circuit board capable of preventing white edges and high-TG circuit board |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116723635A (en) |
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2023
- 2023-06-14 CN CN202310710351.0A patent/CN116723635A/en active Pending
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