CN113271727B

CN113271727B - PCB manufacturing method for improving through hole rate and preventing copper-free hole

Info

Publication number: CN113271727B
Application number: CN202110526371.3A
Authority: CN
Inventors: 邱成伟; 赵强; 刘新发
Original assignee: Huizhou Zhongjing Electronic Technology Co ltd
Current assignee: Huizhou Zhongjing Electronic Technology Co ltd
Priority date: 2021-05-14
Filing date: 2021-05-14
Publication date: 2023-03-14
Anticipated expiration: 2041-05-14
Also published as: CN113271727A

Abstract

The application relates to a PCB manufacturing method for improving the through hole rate and preventing a hole from being copper-free. The method comprises the steps of soaking a first plate to be processed in a copper deposition solution, lifting the first plate to be processed after soaking for a first time, shaking, and alternately performing soaking and shaking to finish copper deposition. Through the soak time of control at heavy copper liquid for heavy copper liquid can fully run through the diaphragm orifice, utilizes hydrodynamics's principle to crowd through the shake simultaneously and breaks the downthehole bubble, makes heavy copper liquid not by the bubble separation, can run through in the hole, and this scheme has improved the penetration hole rate of heavy copper liquid, has prevented the phenomenon that the hole does not have copper.

Description

PCB manufacturing method for improving through hole rate and preventing copper-free hole

Technical Field

The application relates to the technical field of printed circuit board production, in particular to a PCB manufacturing method for improving the through hole rate and preventing a hole from being copper-free.

Background

Printed Circuit Boards (PCBs) are important electronic components, support members for electronic components, and carriers for electrical connection of electronic components.

In recent years, with the further development of electronic information technology and the increasing use requirements of electronic products, the structures of the electronic products are more and more complex, and the functions are more and more comprehensive, so that the Printed Circuit Board (PCB) is promoted to develop towards the following trend. 1. The more and more elements are integrated on the product, so that the power supply product is promoted to develop in the directions of light weight, small size, high precision and high integration along with the market demand; 2. meanwhile, the overcurrent and heat dissipation capability of electronic products is required to adapt to the power consumption environment of high-power devices. The designed finished product direct-current power supply has the advantages that the volume is reduced, the required PCB size is limited, meanwhile, the integration function is enhanced, and the current-carrying capacity is enhanced, so that the high-layer thick copper interconnected PCB is required, and the long-term short circuit, overcurrent and output voltage stability of power supply equipment is met. However, it is difficult to cover the entire copper-plated layer of the PCB uniformly in the hole wall, and the copper-plated layer in the hole is difficult to meet the process requirements during the process of perforating the hole due to the small hole diameter and the large depth.

In the prior art, a PCB manufacturing method CN201811511976.X for preventing occurrence of poor hole plugging or hole plating is used for cleaning foreign matters such as dust or resin in a hole by optimizing process parameters of a board grinding and washing step in a copper plate deposition electric procedure, so that the problem of hole plugging by the foreign matters such as dust is solved, a necessary guarantee is provided for metallization of the hole by subsequent copper deposition and electroplating, and a good metal layer is formed on the hole wall.

An electroplating method CN201810842923.X for preventing high aspect ratio PCB holes from being copper-free comprises the following steps: s1, fluffing a PCB by using a bulking agent; s2, carrying out glue residue removing treatment on the fluffy PCB by adopting a glue residue removing solution; s3, pre-neutralization and ultrasonic neutralization; s4, ultrasonic water washing; s5, hole finishing treatment is carried out on the washed PCB by using a hole finishing agent; s6, carrying out microetching treatment on the PCB by adopting microetching liquid after acid pickling; s7, performing activation treatment after presoaking the PCB by using a presoaking solution; s8, processing the activated PCB by using a speeding agent; s9, depositing copper; and S10, carrying out anti-oxidation treatment. The process solves the problem that the high aspect ratio PCB has no copper in bubbles in holes in the electroplating process under the coordination of the steps and the related reagents

The two schemes provide good necessary guarantee for the step of copper deposition through a chemical treatment mode before copper deposition and related operations, namely are beneficial to preventing copper deposition bubbles on a hole wall, but fail to solve the problem of bubbles in the copper deposition process. Therefore, the PCB manufacturing method can improve the through hole rate and prevent the hole from being copper-free aiming at the problem of bubbles in the copper deposition.

Disclosure of Invention

To overcome the problems in the related art, the present application provides a method for manufacturing a PCB that improves a through-hole ratio and prevents the hole from being copper-free.

The application provides a PCB manufacturing method for improving the through hole rate and preventing a hole from being copper-free, which comprises the steps of carrying out copper deposition pretreatment on a PCB plate to obtain a first board to be treated;

soaking the first board to be processed in a copper deposition solution, lifting the first board to be processed and shaking after soaking for a first time period, and alternately performing soaking and shaking to obtain a second board to be processed;

and carrying out copper deposition post-treatment on the second treatment plate to obtain the metallized PCB.

In one embodiment, before immersing the first board to be processed in the copper deposition solution, lifting the first board to be processed and shaking the first board to be processed after the first immersion time, and alternately performing the immersion and shaking processes to obtain a second board to be processed, the method includes:

soaking the first plate to be processed in whole pore liquid, after soaking for a second time, lifting the first plate to be processed and shaking, and alternately executing the soaking and shaking processes;

and soaking the first plate to be processed in an activating solution, lifting the first plate to be processed and shaking after soaking for a third time period, and alternately executing the soaking and shaking processes.

In one embodiment, the first soaking period is 185-190 seconds, the second soaking period is 200-205 seconds, the third soaking period is 492-497 seconds, the dithering process is performed more than 3 times, the upper and lower dithering amplitudes are 18-20 cm, and the dithering time is 1-2 seconds.

In one embodiment, the copper deposition post-treatment of the second treatment plate includes:

electroplating the second processing plate on the whole plate, wherein the vibration frequency of a motor of the whole plate electroplating is greater than 45 Hz, and the amplitude is greater than 0.2 mm;

and carrying out pattern electroplating and nickel-gold treatment after the whole board is electroplated.

In one embodiment, the current density of the pattern electroplating is less than 12 amperes per square meter, the electroplating time is more than 100 minutes, the vibration frequency of the pattern electroplating is 45-50 hertz, the vibration amplitude is 0.2-0.3 millimeter, and the motor vibration stops alternating.

In one embodiment, the motor vibration frequency of the nickel-gold plating treatment is greater than 45 Hz, the amplitude is greater than 0.2 mm, and the gold ions of the gold plating solution of the nickel-gold plating treatment are greater than 0.55 g/L.

In one embodiment, before the nickel-gold treatment, the method further comprises:

oil removal treatment, wherein the oil removal agent for oil removal treatment is calculated according to the weight percentage: 15-25% of 98% sulfuric acid, 1-10% of 37% hydrochloric acid, 1-11% of hydrofluoric acid and 0-6% of fluorinated alkyl sulfonate.

In one embodiment, the copper deposition pretreatment of the PCB panel includes:

and (3) carrying out pressing treatment on the PCB, and if the number of layers of the PCB after the pressing treatment on the PCB is an odd number, adding a false layer in the pressing treatment and then carrying out pressing treatment.

And carrying out drilling treatment after the PCB plate is subjected to press-fit treatment.

In one embodiment, the drilling process comprises a blind via process, and the blind via process is a copper windowing process.

In one embodiment, the drilling process comprises back drilling, the back drilling further comprising an engineered board edge design inspection back drilling.

The technical scheme provided by the application can comprise the following beneficial effects: this application is through soaking first board that treats in heavy copper liquid, after soaking first time length, then will first board that treats mentions and shakes, and the processing of alternative execution soaking and shake is accomplished heavy copper and is handled. Through controlling the soaking time of heavy copper liquid for heavy copper liquid can fully run through the diaphragm orifice, utilize hydrodynamics's principle to crowd the bubble of breaking in the hole through the shake simultaneously, make heavy copper liquid not by the bubble separation, can run through in the hole, and this scheme has improved the through hole rate of heavy copper liquid, has prevented that the hole from not having the phenomenon of copper.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

The foregoing and other objects, features and advantages of the application will be apparent from the following more particular descriptions of exemplary embodiments of the application, as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts throughout the exemplary embodiments of the application.

FIG. 1 is a flow chart illustrating a PCB fabrication method for improving via ratio and preventing via from being copper-free according to an embodiment of the present application;

fig. 2 is another flow chart illustrating a method for manufacturing a PCB with improved via ratio and preventing copper-free via according to an embodiment of the present application.

Fig. 3 is a structural diagram of a PCB manufactured by a PCB manufacturing method for improving a through-hole ratio and preventing a hole from being copper-free according to an embodiment of the present application.

Detailed Description

Preferred embodiments of the present application will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present application are shown in the drawings, it should be understood that the present application may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

It should be understood that although the terms "first," "second," "third," etc. may be used herein to describe various information, these information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present application. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

Example one

The prior art provides a good necessary guarantee for the step of copper deposition through a chemical treatment mode before copper deposition and related operations, namely, the copper deposition bubbles are prevented from appearing on the hole wall, but the problems that the bubbles appear in the copper deposition process, the through hole rate is improved and the holes are prevented from being copper-free are not solved. Therefore, the PCB manufacturing method for improving the through hole rate and preventing the hole from being copper-free is provided, and the problem that the hole is copper-free due to bubbles generated in the copper deposition process is solved.

The technical solutions of the embodiments of the present application are described in detail below with reference to the accompanying drawings.

With reference to figures 1 and 2 of the drawings,

a PCB manufacturing method for improving the through hole rate and preventing the hole from being copper-free comprises the following steps:

101, carrying out copper deposition pretreatment on a PCB plate to obtain a first board to be treated;

the copper deposition pretreatment refers to the process flow treatment which is required to be carried out before the copper deposition of the PCB, and comprises cutting, inner layer graph manufacturing, pressing, drilling and the like;

the first board to be processed is a PCB board to be processed obtained from a cutting process to a drilling process.

And the lamination is to pre-laminate the inner core board, the prepreg PP and the outer copper foil to form a pre-laminated structure, and then select proper lamination conditions according to the melting point of the board material to press the pre-laminated structure into a whole to form the multilayer board.

And drilling after the pressing is finished, wherein the types of the drilling comprise buried holes, blind holes 10, back drilling holes 30, through holes 20 and the like, and the types of the drilling, the depth of the holes and the aperture size are determined according to actual requirements.

The blind hole 10 is shown in fig. 3: the outermost circuitry of the PCB is connected with the adjacent inner layers with plated holes, so called blind holes 10, because the opposite side is not visible.

The blind hole 10 can be made by a copper window. Manufacturing a copper window: utilizing a laser machine to open a copper window on the copper layer of the multilayer flexible board; and after the copper window is opened, the substrate layer is heated to a molten state by a laser machine and gasified to form the blind hole 10.

The back drilling holes 30 are drilled according to the required depth, and meanwhile, the back drilling holes 30 are copied to the plate edge to be used for slice drawing and testing to confirm the hole site depth, so that the situation that the back drilling holes in the unit are rejected due to disqualification can be avoided. The plate edge back-drilled holes 30 are replicated to match the back-drilled holes 30 parameters, including the number of holes, the diameter of the holes, the location of the holes, etc. of the back-drilled holes 30.

102, soaking a first plate to be processed in a copper deposition solution, after soaking for a first time, lifting the first plate to be processed, shaking, and alternately performing soaking and shaking to obtain a second plate to be processed;

two important steps are included before the first plate to be processed is soaked in the copper deposition solution, namely, the whole hole processing is firstly carried out and then the activation processing is carried out.

201, soaking a first board to be processed in whole pore liquid, lifting the first board to be processed and shaking the first board to be processed after soaking for a second time, and alternately performing soaking and shaking processes;

the whole-hole treatment is to soak the first board to be treated before copper deposition in the whole-hole solution, and the parameters of the whole-hole solution are not limited in this embodiment and can be determined according to actual conditions. When in soaking, a vibration motor is adopted for vibration, the vibration frequency is more than 45 Hz, and the amplitude is more than 0.2 mm. Soaking for 185-190 seconds, then lifting the first plate to be processed, shaking the plate by a lifting arm by using a servo motor for more than 3 times, wherein the shaking amplitude is 18-20 cm, the shaking time is more than 1 second, and then putting the first plate to be processed back into the whole pore solution to soak for 185-190 seconds.

The purpose of the whole holes is to cover the glass fibers on the whole surfaces of the holes, so that effective adsorption of the catalyst by the plates is ensured.

202 soaking the first plate to be treated in the activating solution, and after soaking for a third period of time,

lifting the first plate to be processed, shaking the first plate to be processed, and alternately performing soaking and shaking processes;

the whole hole treatment is followed by an activation treatment, and the first plate to be treated is soaked in the activation solution, and the parameters of the activation solution are not limited in this embodiment and can be determined according to actual conditions. When in soaking, a vibration motor is adopted for vibration, the vibration frequency is more than 45 Hz, and the amplitude is more than 0.2 mm. The soaking time is 200-205 seconds, then the first plate to be processed is lifted, the plate is shaken by a lifting arm through a servo motor, the shaking frequency is more than 3 times, the upper and lower shaking amplitude is 18-20 cm, the shaking time is more than 1 second, and then the first plate to be processed is placed back into the activating solution to be soaked for 200-205 seconds.

The purpose of activation is to make the catalyst deposit on the surface of the pore wall uniformly and densely, and ensure the initial reaction of copper deposition and good combination of copper and the pore wall.

After the activation treatment, the first board to be treated is subjected to copper deposition treatment, and the first board to be treated is soaked in a copper deposition solution, and parameters of the copper deposition solution are not limited in this embodiment and can be determined according to actual conditions. When in soaking, a vibration motor is adopted for vibration, the vibration frequency is more than 45 Hz, and the amplitude is more than 0.2 mm. The soaking time is 492-497 seconds, then the first plate to be processed is lifted, the servo motor is used for shaking the plate through the lifting arm, the shaking frequency is more than 3 times, the upper and lower shaking amplitude is 18-20 centimeters, the shaking time is more than 1 second, and then the first plate to be processed is placed back into the copper deposition solution to be soaked for 492-497 seconds, so that the second plate to be processed is obtained. The activity of the copper precipitation liquid is controlled to be 0.2-0.3 square feet per liter.

103, carrying out copper deposition post-treatment on the second treatment plate to obtain the metallized PCB.

The copper deposition post-treatment comprises the procedures of whole-board electroplating, pattern electroplating, nickel and gold melting, testing, packaging and the like, so that the qualified metallized PCB with high penetration rate and no copper and no hole can be obtained.

After the second processing plate is obtained, full-plate electroplating needs to be carried out on the second board to be processed, the vibration frequency of a motor for full-plate electroplating is larger than 45 Hz, and the amplitude is larger than 0.2 mm. The parameters of the plating solution are not limited in this embodiment and can be determined according to actual conditions. The thickness of the electroplated copper is based on actual requirements.

And carrying out pattern electroplating after the whole board electroplating, wherein the current density of the pattern electroplating is less than 14 amperes per square meter, the electroplating time is more than 100 minutes, the specific current density and the electroplating time are determined according to actual requirements, the vibration frequency of a motor is 45-50 Hz, the amplitude is 0.2-0.3 mm, the motor vibration is carried out by alternative vibration in a mode of stopping for 10 seconds after 25 seconds, the copper plating thickness of holes is more than or equal to 25.4 micrometers, and the tin plating thickness is 8-12 micrometers.

And carrying out nickel-gold treatment after the pattern electroplating. And before nickel and gold treatment, oil removal treatment is required.

The degreasing agent for degreasing treatment comprises the following components in percentage by weight: 15-25% of 98% sulfuric acid, 1-10% of 37% hydrochloric acid, 1-11% of hydrofluoric acid and 0-6% of fluorinated alkyl sulfonate.

And after the oil removal treatment, carrying out nickel-gold treatment on the second board to be treated, wherein the motor vibration frequency of the nickel-gold treatment is greater than 45 Hz, the amplitude is greater than 0.2 mm, and the gold ions in the gold solution are required to be greater than 0.55 g per liter.

And (4) after nickel and gold treatment, carrying out forming, testing, packaging and other treatment to obtain the metallized PCB.

The test can use an automatic optical inspection system to detect whether the outer layer circuit has defects such as open circuit, gap, incomplete etching, short circuit, etc. by comparing with Computer Aided Manufacturing (CAM) data.

This application is through soaking first board that treats in heavy copper liquid, after soaking first time length, then mentions first board that treats and shakes, and the processing of carrying out soaking and shake in turn accomplishes heavy copper and handles. Through controlling the soaking time of the copper deposition solution, the copper deposition solution can fully penetrate through the plate hole, meanwhile, bubbles in the hole are broken through shaking by utilizing the fluid dynamics principle, the copper deposition solution is not blocked by the bubbles, the penetration rate of the copper deposition solution is improved, and the phenomenon that the hole is free of copper is prevented.

Example two

The above embodiment introduces a method for manufacturing a PCB with improved through-hole ratio and no copper in a hole, and this embodiment will combine this method to manufacture a 14-layer PCB with high aspect ratio, which includes the following steps:

the copper deposition pretreatment comprises cutting, inner layer pattern making, pressing and drilling;

Pressing the PCB plate;

in the embodiment, the PCB is a 14-layer high aspect ratio PCB, and L1-7 and L8-14 layers are designed to be blind hole layers;

the blind hole layers of the 14-layer PCB with the high aspect ratio are L1-7 layers and L8-14 layers, the blind hole layers are needed to be laminated once, and finally, two blind hole layers are laminated. Because the blind hole layer is an odd layer, the odd layer is easy to bend due to asymmetric design and unbalanced internal stress in the prior art. The embodiment of the application of the self is manufactured into two standard 8-layer blind hole laminated plates by adding two false layers, the added positions are arranged between an L7 layer and an L8 layer to form L7 'and L8' false layers, as shown in figure 3, the purpose of adding the false layers is to balance the residual copper rate between layers in order to design a disconnected copper block pattern, the main purpose is to improve and balance the weight of each layer, so as to ensure that the whole stress is uniform, and the phenomenon of bending deformation caused by the influence of the stress in the processing process can be avoided. Besides improving the bending of the laminated board, the manufactured dummy layer can protect the PCB by manufacturing copper pads in the corresponding blind hole positions in the follow-up manufacturing process, and can prevent the L7 and L8 layers of holes from being opened due to the fact that L1-7 and L8-14 layers of holes are corroded by copper.

Drilling after the blind hole layer is laminated;

the blind hole of the embodiment of the application is manufactured in a copper window opening mode. Manufacturing a copper window: utilizing a laser machine to open a copper window on the copper layer of the multilayer flexible board; and after the copper window is opened, the substrate layer is heated to a molten state by a laser machine and gasified to form the blind hole 10.

The blind hole laminate after press drilling is called a first board to be processed and soaked in the whole-hole liquid, and parameters of the whole-hole liquid are not limited in this embodiment and can be determined according to actual conditions. When in soaking, a vibration motor is adopted for vibration, the vibration frequency is 45 Hz, and the amplitude is 0.2 mm. The soaking time is 185 seconds, then the plate is lifted up, the plate is shaken by a lifting arm by a servo motor for 3 times, the shaking frequency is 20 centimeters up and down, the shaking time is 1 second, and then the plate is put back into the whole pore solution to be soaked for 185 seconds.

The plate after the whole hole treatment needs to be subjected to activation treatment, and the plate after the whole hole treatment is soaked in the activation solution, and the parameters of the activation solution are not limited in the embodiment and can be determined according to actual conditions. When in soaking, a vibration motor is adopted for vibration, the vibration frequency is more than 45 Hz, and the amplitude is more than 0.2 mm. The soaking time is 200 seconds, then the plate is lifted, the servo motor is used for shaking the plate through the lifting arm, the shaking frequency is 3 times, the shaking amplitude is 20 centimeters up and down, the shaking time is 1 second, and then the plate is placed back into the activating solution to be soaked for 200 seconds.

And performing copper deposition treatment after the activation treatment, and soaking the activated plate in a copper deposition solution, wherein parameters of the copper deposition solution are not limited in the embodiment and can be determined according to actual conditions. When in soaking, a vibration motor is adopted for vibration, the vibration frequency is 45 Hz, and the amplitude is 0.2 mm. The soaking time is 492 seconds, then the plate is lifted, the plate is shaken by a lifting arm through a servo motor, the shaking frequency is 3 times, the upper shaking amplitude is 20 centimeters and the lower shaking amplitude is 1 second, and then the plate is placed back into the copper deposition solution to be soaked for 492 seconds, so that a second plate to be processed is obtained. The activity of the copper precipitation liquid is controlled in a load amount of 0.2-0.3 square feet per liter.

In this embodiment, a 14-layer PCB with a high aspect ratio is taken as an example, after a second processing board is obtained, full board electroplating needs to be performed on the second board to be processed, the vibration frequency of a motor of the full board electroplating is greater than 45 hz, and the amplitude of the motor is greater than 0.2 mm. The parameters of the plating solution are not limited in this embodiment and can be determined according to actual conditions. The electroplated copper thickness was 25 microns. And (4) carrying out resin hole plugging and outer layer pattern manufacturing after the whole plate is electroplated. Then, an automatic optical inspection system is used to inspect whether the outer layer circuit has defects such as open circuit, gap, incomplete etching, short circuit, etc. by comparing with Computer Aided Manufacturing (CAM) data.

After the processing of the L1-7 and L8-14 blind hole layers is finished, second pressing is needed, the L1-7 and L8-14 layers of the two blind hole layers are pressed, copper windows are opened, through hole processing is carried out, copper plate deposition electric processing is carried out, back drilling holes 30 are carried out, copper plate deposition electric processing is carried out, and the specific steps refer to the step flows of 101 drilling holes, 102 copper deposition and 103 full-plate electroplating.

And (3) carrying out pattern electroplating after the flow of the steps is completed, wherein the current density of the pattern electroplating is less than 14 amperes per square meter, the electroplating time is more than 100 minutes, the specific current density and the electroplating time are determined according to actual requirements, the vibration frequency of a motor is 45 Hz, the amplitude is 0.2 mm, the motor vibration is carried out in an alternating vibration mode of stopping for 10 seconds in 25 seconds, the thickness of hole copper plating is 25.4 micrometers, and the thickness of tin plating is 8-12 micrometers.

And etching the outer layer after pattern electroplating, and performing anti-oxidation treatment after the steps of the detection flow of an automatic optical detection system, wherein the anti-oxidation treatment comprises nickel-gold treatment. And oil removal treatment is required before nickel-gold treatment.

The degreasing agent for degreasing treatment comprises the following components in percentage by weight: 15% of 98% sulfuric acid, 5% of 37% hydrochloric acid, 6% of hydrofluoric acid and 3% of fluorinated alkyl sulfonate.

And after oil removal treatment, carrying out nickel-gold treatment on the board, wherein the motor vibration frequency of the nickel-gold treatment is 45 Hz, the amplitude is 0.2 mm, and the gold ion concentration of the gold solution is more than 0.55 g per liter.

And (3) after nickel and gold treatment, carrying out forming, electrical test, packaging and the like on the board to obtain the 14-layer metalized PCB with high aspect ratio and no holes and no copper.

The embodiment is a method for manufacturing a high-aspect-ratio PCB with improved through hole rate and copper-free holes, the method comprises the steps of controlling the soaking time of a copper deposition solution, enabling the copper deposition solution to fully penetrate through hole holes, simultaneously squeezing bubbles in the holes through shaking by utilizing the principle of fluid dynamics, enabling the copper deposition solution not to be blocked outside the holes by the bubbles, electroplating a pattern on the copper deposition plate, electroplating the pattern, controlling the vibration frequency and the vibration amplitude of a motor in the nickel-gold melting process, adding vibration in the electroplating process, further accelerating the exchange of liquid in the holes, further improving the deep plating capacity, improving and balancing the weight of each layer by increasing a dummy plate, ensuring the uniform integral stress, and solving the phenomenon of bending deformation of the plate in the pressing process.

EXAMPLE III

The embodiment of the invention describes a method for manufacturing a high-aspect-ratio PCB to improve the through-hole ratio and prevent the hole from being free of copper, and the method for manufacturing the PCB to improve the through-hole ratio and prevent the hole from being free of copper is also suitable for ordinary PCBs with non-high aspect ratios, and comprises the following specific steps:

101, carrying out copper deposition pretreatment on a PCB to obtain a first board to be treated;

the first board to be processed is a PCB board to be processed obtained from the material cutting process to the drilling process.

The pretreatment of copper deposition on the PCB comprises pressing, wherein: and pre-laminating the inner core plate, the prepreg PP and the outer copper foil to form a pre-laminated structure, and then pressing the pre-laminated structure into a whole by selecting proper laminating conditions according to the melting point of the plate materials to form the multilayer plate.

If the number of layers of the PCB is odd, a dummy layer can be added and then pressed, the purpose of adding the dummy layer is to design a non-communicated copper block pattern to balance the residual copper rate among the layers, and the main purpose is to improve and balance the weight of each layer so as to ensure that the whole is uniformly stressed and the phenomenon of bending deformation caused by the influence of stress in the processing process is avoided.

After the lamination is completed, drilling is performed, including blind drilling, back drilling 30 and through holes 20.

The blind hole 10 of the embodiment of the present application is manufactured by a copper window. Manufacturing a copper window: utilizing a laser machine to open a copper window on the copper layer of the multilayer flexible board; and after the copper window is opened, the substrate layer is heated to a molten state by a laser machine and gasified to form the blind hole 10.

The back drilling holes 30 are drilled according to the required depth, meanwhile, the back drilling holes 30 are copied to the plate edge to be used for slicing, drawing and measuring to confirm the hole site depth, and the back drilling holes 30 in the unit are prevented from being scrapped. The plate edge back-drilled holes 30 are replicated to match the back-drilled holes 30 parameters, including the number of holes, the diameter of the holes, the location of the holes, etc. of the back-drilled holes 30.

The whole-hole treatment is to soak the first board to be treated before copper deposition in the whole-hole solution, and the parameters of the whole-hole solution are not limited in this embodiment and can be determined according to actual conditions. During soaking, a vibration motor is adopted for vibration, the vibration frequency is 50 Hz, and the amplitude is 0.3 mm. The soaking time is 190 seconds, then the first plate to be processed is lifted, the plate is shaken by the lifting arm through the servo motor, the shaking frequency is 3 times, the upper shaking amplitude and the lower shaking amplitude are 20 centimeters, the shaking time is 1 second, and then the first plate to be processed is placed back into the whole pore liquid to be soaked for 190 seconds.

The whole hole treatment is followed by an activation treatment, and the first plate to be treated is soaked in the activation solution, and the parameters of the activation solution are not limited in this embodiment and can be determined according to actual conditions. During soaking, a vibration motor is adopted for vibration, the vibration frequency is 50 Hz, and the amplitude is 0.3 mm. The soaking time is 205 seconds, then the first plate to be processed is lifted, the plate is shaken by the lifting arm through the servo motor, the shaking frequency is 3 times, the upper shaking amplitude and the lower shaking amplitude are 20 centimeters, the shaking time is 1 second, and then the first plate to be processed is placed back into the activating solution to be soaked for 205 seconds.

After the activation treatment, the first board to be treated is subjected to copper deposition treatment, and the first board to be treated is soaked in a copper deposition solution, and parameters of the copper deposition solution are not limited in this embodiment and can be determined according to actual conditions. When soaking, the vibration motor is adopted to vibrate, the vibration frequency is 50 Hz, and the amplitude is 0.3 mm. Soaking time is 497 seconds, then lifting the first board to be processed, shaking the board by the aid of the servo motor through the lifting arm for 3 times, shaking up and down by 20 centimeters, shaking time is 1 second, and then placing the first board to be processed back into the copper deposition solution to be soaked for 497 seconds to obtain a second board to be processed. The activity of the copper precipitation liquid is controlled to be 0.2-0.3 square feet per liter.

And 103, carrying out copper deposition post-treatment on the second treatment plate to obtain the metallized PCB.

After the second processing plate is obtained, full-plate electroplating needs to be carried out on the second processing plate, wherein the vibration frequency of a motor for full-plate electroplating is 50 Hz, and the amplitude is 0.3 mm. The parameters of the plating solution are not limited in this embodiment and can be determined according to actual conditions. The electroplated copper thickness is greater than or equal to 25 microns. And (4) carrying out resin hole plugging and outer layer pattern manufacturing after the whole plate is electroplated.

The copper deposition post-treatment also comprises pattern electroplating, the current density of the pattern electroplating is less than 14 amperes per square meter, the electroplating time is more than 100 minutes, the specific current density and the electroplating time are determined according to actual requirements, the vibration frequency of a motor is 50 Hz, the amplitude is 0.3 mm, the vibration is performed in a mode of stopping for 10 seconds by vibration for 25 seconds, the copper plating thickness of a hole is at least 25.4 micrometers, and the tin plating thickness is 8-12 micrometers.

And (3) etching the outer layer after pattern electroplating, and performing anti-oxidation treatment after the detection flow step of an automatic optical detection system, wherein the anti-oxidation treatment comprises nickel and gold treatment. And oil removal treatment is required before nickel-gold treatment.

The degreasing agent for degreasing treatment comprises the following components in percentage by weight: 20% of 98% sulfuric acid, 8% of 37% hydrochloric acid, 7% of hydrofluoric acid and 3% of fluorinated alkyl sulfonate.

And after the oil removal treatment, carrying out nickel-gold treatment on the second board to be treated, wherein the motor vibration frequency of the nickel-gold treatment is 50 Hz, the amplitude is 0.3 mm, and the gold ion concentration of the gold solution is more than 0.55 g/L.

And after the nickel and gold treatment, carrying out forming, electrical testing, packaging and other treatment on the second treatment plate to obtain the metalized PCB with high through hole rate and no copper holes.

The first board to be processed is soaked in the copper deposition solution, after the first board to be processed is soaked for a first time period, the first board to be processed is lifted and shaken, and the soaking and shaking processes are alternately executed to complete the copper deposition process. Through the soaking time of control at heavy copper liquid for heavy copper liquid can fully run through the diaphragm orifice, utilizes hydrodynamics's principle to crowd through the shake simultaneously and breaks the downthehole bubble, makes heavy copper liquid not by the bubble separation outside the hole, adds vibrations and control vibration frequency and amplitude at the electroplating process simultaneously, has improved the penetration rate of heavy copper liquid and other plating solutions, has prevented that the hole from not having the phenomenon of copper.

Having described embodiments of the present application, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for manufacturing a PCB with improved through-hole ratio and no copper in the hole is characterized in that,

carrying out copper deposition pretreatment on a PCB plate to obtain a first plate to be treated;

carrying out copper deposition post-treatment on the second treatment plate to obtain a metallized PCB;

the copper deposition post-treatment of the second treatment plate comprises:

carrying out pattern electroplating and nickel-gold treatment after the whole board electroplating; the current density of the pattern electroplating is less than 12 amperes per square meter, the electroplating time is more than 100 minutes, the vibration frequency of the pattern electroplating is 45-50 Hz, the vibration amplitude is 0.2-0.3 mm, and the motor vibration is stopped alternately;

the soaking of the first board to be processed in the copper deposition solution, after the first board to be processed is soaked for a first time, the first board to be processed is lifted and shaken, and the soaking and shaking are alternately performed before a second board to be processed is obtained, the method comprises the following steps:

soaking the first board to be processed in the whole pore liquid, after soaking for a second time, lifting the first board to be processed and shaking, and alternately executing the soaking and shaking processes;

soaking the first board to be processed in an activating solution, after soaking for a third time, lifting the first board to be processed and shaking, and alternately performing soaking and shaking;

the first soaking time is 185-190 seconds, the second soaking time is 200-205 seconds, the third soaking time is 492-497 seconds, the dithering times are more than 3 times, the upper and lower dithering amplitudes are 18-20 centimeters, and the dithering times are 1-2 seconds;

the vibration frequency of the motor for nickel-gold melting treatment is greater than 45 Hz, the amplitude is greater than 0.2 mm, and the gold ions in the gold melting liquid for nickel-gold melting are greater than 0.55 g/L;

before the nickel-gold treatment, the method further comprises the following steps:

and (3) oil removal treatment, wherein the oil removal agent for oil removal treatment is calculated according to the weight percentage: 15-25% of 98% sulfuric acid, 1-10% of 37% hydrochloric acid, 1-11% of hydrofluoric acid and 0-6% of fluorinated alkyl sulfonate;

carry out heavy copper pretreatment to the PCB sheet material, include:

performing press-fit treatment on the PCB, and if the number of layers of the PCB after the press-fit treatment on the PCB is odd, adding a dummy layer in the press-fit treatment and then performing press-fit;

after the PCB is subjected to press-fit treatment, drilling treatment is carried out;

the drilling treatment comprises blind hole treatment, and the blind hole treatment adopts a copper window opening mode; the drilling process comprises back drilling, and the back drilling further comprises engineering plate edge design inspection back drilling.