A method for enhancing the soldering reliability of a BT package substrate PCB

Abstract

The application relates to a BT packaging substrate PCB soldering reliability enhancement method, and belongs to the technical field of PCBs. The method comprises the following steps: a PCB plate is pre-designed to form a metalized half-hole; a PCB plate design process with the metalized half-hole comprises the following steps: drilling is performed on a packaging substrate to form a PCB continuous substrate with two rows of metalized holes; chemical copper deposition and full-plate copper plating treatment are further performed on the PCB continuous substrate; line transfer treatment is performed; then, copper and tin are electroplated on the PCB continuous substrate pattern; half-hole is performed after the copper and tin are electroplated; alkaline etching treatment is performed on the whole PCB continuous substrate; and nickel gold electroplating is performed on the PCB continuous substrate; the metalized half-hole is formed before the nickel gold electroplating; after the nickel gold electroplating, the nickel gold wraps the full-plate copper layer of the PCB continuous substrate; the application can make the nickel gold completely wrap the copper plating layer after the nickel gold electroplating, can make the soldering process safe and reliable, and can avoid the problems that copper ions of the PCB plate are precipitated to affect solderability and PCB plate reliability.

Description

TECHNICAL FIELD

[0001] The application relates to a BT packaging substrate PCB soldering reliability enhancement method and belongs to the technical field of PCBs. BACKGROUND

[0002] The packaging substrate can provide a chip with electrical connection, protection, support, heat dissipation, assembly and the like to realize multi-pin, reduce the volume of a packaging product, improve electrical performance and heat dissipation, and achieve the purpose of ultrahigh density or multi-chip modularization. The packaging substrate is developing in the direction of high density, and the laminated multilayer board is a new type of PCB product technology that can realize high density of the packaging substrate. The PCB is a short name of a printed circuit board, also known as a printed wiring board, is an important electronic component, is a support body of electronic components, and is a carrier for electrical interconnection of electronic components. In the prior art, after the PCB is completed, a packaging factory cuts the PCB into single pieces by using a water jet cutting method. While cutting into single pieces, the metal half-hole on the PCB is divided into two parts, and then soldering is performed. After the packaging factory cuts the PCB into single pieces, the metal half-hole is evenly divided, and the half-hole metal cannot form a nickel gold layer to wrap the copper layer. During the soldering process, copper ions seriously affect the solderability and PCB reliability.

[0003] Therefore, the application provides a BT packaging substrate PCB soldering reliability enhancement method. SUMMARY

[0004] The application aims to provide a BT packaging substrate PCB soldering reliability enhancement method to solve the above problems. The method has the effect that the nickel gold completely wraps the copper plating layer after electroplating nickel gold on the PCB continuous piece substrate, and the soldering process is safe and reliable, and copper ion precipitation on the PCB does not affect the solderability and PCB reliability.

[0005] The application achieves the above object by the following technical scheme. A BT packaging substrate PCB soldering reliability enhancement method includes the following steps.

[0006] Step 1: First, the packaging substrate is cut according to the substrate specification and the cutting specification, the packaging substrate is cut into the required size, the packaging substrate is polished by using a grinding machine, and the polishing temperature of the grinding machine is controlled to be between 85 DEG C and 95 DEG C, so as to complete the preparation of cutting, and drilling is performed on the packaging substrate to form a PCB continuous piece substrate with two rows of metalized holes.

[0007] Step two: further chemical copper deposition and full-plate copper plating treatment is performed on the PCB continuous sheet substrate, and line transfer treatment is performed, then the PCB continuous sheet substrate pattern is electroplated with copper and tin, and after the pattern is electroplated with copper and tin, half-hole is performed;

[0008] Step three: the whole PCB continuous sheet substrate is subjected to alkaline etching treatment, the PCB continuous sheet substrate after alkaline etching treatment is subjected to automatic optical inspection (AOI) and solder mask treatment, and electroplated nickel gold is performed on the PCB continuous sheet substrate, the metalized half-hole is formed before the electroplated nickel gold, and after the electroplated nickel gold, the nickel gold wraps the full-plate copper layer of the PCB continuous sheet substrate;

[0009] Step four: the PCB continuous sheet substrate is cut into single pieces by water jet cutting method, the water jet does not need to cut the metalized half-hole, the plating layer of the metalized half-hole will not be damaged, and the PCB continuous sheet substrate after cutting forms a nickel gold wrapped copper physical PCB board, which is subjected to electrical measurement and FQC inspection, and then taken for soldering or packaging.

[0010] Further, in order to be able to insert the electrical components into the through hole between the layers of the packaging substrate for soldering, the drilling method in step one is laser drilling, laser is reflected and focused through the lens and then hits on the packaging substrate, is absorbed by the packaging substrate to produce instantaneous high temperature, ablates the copper layer and the dielectric layer, and makes the through hole between the layers of the packaging substrate, so as to connect each layer of the packaging substrate.

[0011] Further, in order to improve the quality of the production line board, prevent the problem of via hole not passing and open short circuit, improve the solderability, and prevent quality problems of the product, only the chemical copper deposition treatment in step two is used to deposit a thin layer of chemical copper on the non-conductive hole wall substrate after drilling, the chemical copper deposition treatment process is to remove the surface oil and oxide of the PCB continuous sheet substrate, adjust the negative charge of the hole wall to positive charge to adsorb colloidal palladium, and expose the palladium nucleus, and finally through the activation of the palladium nucleus to induce chemical copper deposition autocatalytic reaction, so that the copper deposition reaction continues, and a layer of chemical copper is covered on the hole wall.

[0012] Further, in order to remove the oxide on the copper surface of the line, the ink residual film and the glue, and ensure the bonding force between the first copper and the pattern electroplated copper or nickel, the full-plate copper plating treatment is used to protect the thin layer of chemical copper formed by the chemical copper deposition treatment, and the full-plate copper plating treatment process is to remove the surface rust of the PCB continuous sheet substrate as a cathode, a pure copper plate as an anode, and hang in an alkaline electroplating solution containing cuprous cyanide, sodium cyanide and sodium carbonate, etc., and perform alkaline cyanide copper plating.

[0013] Further, in order to make the coating film thickness uniform, and to avoid the problem of too many pinholes and impurities on the board surface after coating, the line transfer process is used to transfer the image on the production film to the PCB sheet substrate. The line transfer process is as follows: according to the size of the printed layout, the copper-clad plate is cut to match the actual circuit diagram size, and the copper-clad plate is kept clean, and the circuit is printed on the copper-clad plate.

[0014] Further, in order to make the PCB sheet substrate have the advantages of corrosion resistance and easy soldering, electroplating copper-tin on the PCB sheet substrate pattern is used to electroplate a layer of copper layer and a layer of tin layer with the required thickness on the exposed copper skin or the hole wall of the circuit pattern. The electroplating copper-tin process is as follows: plate, oil removal, water washing twice, micro-etching, water washing, pickling, copper plating, water washing, acid immersion, tin plating, water washing, and plate.

[0015] Further, in order to protect the effective pattern part by the anti-etching performance of the dry film, wet film, tin layer, and nickel metal layer, the alkaline etching process in step three is used to corrode and remove the copper layer in the non-circuit part by chemical reaction. The alkaline etching process is as follows: first, the copper surface without anti-etching layer protection is etched by alkaline copper chloride solution, and then the anti-etching layer is removed according to the type of the PCB sheet substrate by different processing methods.

[0016] Further, in order to ensure the electrical function of the product and ensure the reliability of the product, and to control the quality in the hole by the solder resist process, so that the solder resist does not appear in the hole of the printed board, ensuring the quality of the printed board, the automatic optical inspection (AOI) process is used to detect suspected defects by optical means, by which the lens reads the reflected light of the PCB sheet substrate, and the computer calculates. The solder resist process is used to remove the oxides and impurities on the surface of the PCB sheet substrate, roughen the copper surface, and increase the contact area between the surface of the PCB sheet substrate and the solder resist by combining chemical pickling, mechanical brushing, and sandblasting.

[0017] Further, in order to prevent the diffusion of copper ions under the action of the nickel layer by taking the nickel layer as a barrier layer, and to improve the product quality of the PCB by the electrical test and the FQC inspection, the electroplated nickel-gold process is used to improve the wear resistance of the PCB sheet substrate and wrap the copper plating layer. The electrical test and the FQC inspection are used to detect defective products of the PCB board.

[0018] The technical effect and advantage of the present application: by designing the PCB continuous sheet substrate as two rows of metallized holes, and after copper electroplating, the nickel gold is completely wrapped around the copper layer after electroplating nickel gold, and when the PCB continuous sheet substrate is cut into single by the water jet, the water jet does not need to cut the metallized half hole, so that the plated layer of the metallized half hole will not be damaged, the nickel gold layer properly wraps the copper layer, the soldering process is safe and reliable, and there is no copper ion precipitation on the PCB board affecting the solderability and PCB board reliability. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The flow chart for the PCB of the present application is designed;

[0020] Figure 2 The PCB continuous sheet substrate design of the present application is designed;

[0021] Figure 3 The nickel gold layer and copper layer cross section schematic diagram of the present application is shown;

[0022] Figure 4 The physical PCB of the present application is shown;

[0023] Figure 5 The PCB continuous sheet substrate design of the prior art is shown;

[0024] Figure 6 The nickel gold layer and copper layer cross section schematic diagram of the prior art is shown;

[0025] Figure 7 The physical PCB of the prior art is shown; DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0027] Please refer to Figures 1-7As shown, a BT package substrate PCB soldering reliability enhancement method, including the PCB board is designed to form a metallized half-hole in advance, the PCB board design process with metallized half-hole includes, first of all according to the substrate specification and cutting specification to cutting package substrate, cutting package substrate into the required size, using the grinding machine to polish the package substrate, and control the polishing temperature of the grinding machine between 85-95 DEG C, in this way to complete the preparation of cutting, and drilling on the package substrate, form a PCB continuous sheet substrate with two rows of metallized holes, further to the PCB continuous sheet substrate chemical copper and full plate copper plating treatment, and line transfer processing, then the PCB continuous sheet substrate pattern is electroplated with copper tin, after the copper tin electroplating, the PCB continuous sheet substrate is subjected to alkali etching treatment, the PCB continuous sheet substrate after alkaline etching treatment is subjected to automatic optical inspection (AOI) and solder resist treatment, and electroplated nickel gold is carried out on the PCB continuous sheet substrate, the metallized half-hole is formed before electroplated nickel gold, after electroplated nickel gold, the nickel gold wraps the full plate copper layer of the PCB continuous sheet substrate, finally, the PCB continuous sheet substrate is cut into a single by using a water jet cutting method, the water jet does not need to cut to the metallized half-hole, the plating layer of the metallized half-hole will not be damaged, the PCB continuous sheet substrate after cutting forms a nickel gold wrapped copper physical PCB board, after the nickel gold wrapped copper physical PCB board is subjected to electrical measurement and FQC inspection, it is taken to solder or packaged, such as Figures 5-7 As shown, the traditional package substrate, after the PCB is completed, the packaging factory adopts a water jet cutting method to cut the PCB continuous sheet substrate into a single, while cutting into a single, the metal half-hole on the PCB board needs to be divided into two parts, and then soldering is carried out, the PCB board is designed to form a metallized half-hole in advance on the basis of this, the half-hole is formed before electroplated nickel gold, after electroplated nickel gold, the nickel gold completely wraps the copper layer, when the water jet cuts the PCB continuous sheet into a single, the water jet does not need to cut to the metallized half-hole, so that the plating layer of the metallized half-hole will not be damaged, the nickel gold layer properly wraps the copper layer, the soldering process is safe and reliable, and there is no copper ion precipitation on the PCB board to affect the solderability and PCBA reliability of soldering, which completely solves the copper ion precipitation caused by water jet cutting of the metallized hole, and completely solves the solderability and PCBA reliability of soldering.

[0028] The drilling method in step one is laser drilling, laser is reflected and focused through a lens and then hits the package substrate, is absorbed by the package substrate to produce instantaneous high temperature, ablates the copper layer and the dielectric layer, forms a through hole between the layers of the package substrate, and achieves the connection between the layers of the package substrate. Drilling is under high voltage at the electrode end, and laser is generated by filling laser gas in the middle of the electrode when electrolytic gas is generated. After reflection, perspective and focusing through a lens, it hits the board, is absorbed by the board to produce instantaneous high temperature, ablates the copper layer and the dielectric layer, and forms a small circular hole between the two layers. After copper plating in the later process, a conductive blind hole is formed.

[0029] The chemical copper plating in step two is used to deposit a thin layer of chemical copper on the drilled non-conductive hole wall substrate by chemical method. The chemical copper plating process removes the oil and oxide on the surface of the PCB panel substrate, adjusts the negative charge of the hole wall to positive charge to adsorb colloidal palladium, and exposes the palladium nucleus. Finally, the chemical copper plating self-catalytic reaction is induced by the activation of the palladium nucleus, so that the copper plating reaction continues to proceed, covering a layer of chemical copper on the hole wall. The copper plating process plays an important role in PCB design. The chemical copper plating process improves the quality of the PCB, avoids the main problems of via non-communication and open short circuit, prevents batch problems, and avoids quality risks of the PCB.

[0030] The full-plate copper plating process is used to protect the thin layer of chemical copper formed by the chemical copper plating process. The full-plate copper plating process is as follows: after removing the oil and rust on the surface of the PCB panel substrate, the substrate is used as a cathode, a pure copper plate is used as an anode, and the substrate is hung in an alkaline electroplating solution containing cuprous cyanide, sodium cyanide, and sodium carbonate. The substrate is subjected to alkaline cyanide copper plating. In use, the thin layer of chemical copper is effectively protected from oxidation and acid erosion.

[0031] The circuit transfer process is used to transfer the image on the production film to the PCB panel substrate. The circuit transfer process is as follows: the copper-clad plate is cut according to the size of the printed layout to match the actual circuit diagram size, and the copper-clad plate is kept clean. The circuit is printed on the copper-clad plate. The film baseboard is a mechanical support for fixing and assembling various electronic components such as integrated circuits in the production of printed circuit boards, and provides the required electrical characteristics. The image on the production film is transferred to the PCB panel substrate by the circuit transfer process, providing solder mask patterns for automatic soldering, and providing identification characters and patterns for component insertion, inspection, and maintenance.

[0032] Electroplating copper and tin on the PCB panel substrate pattern is used to electroplate a layer of copper and a layer of tin with the required thickness on the exposed copper skin or hole wall of the circuit pattern. The electroplating copper and tin process is as follows: plate, oil removal, water washing twice, micro-etching, water washing, pickling, copper plating, water washing, acid immersion, tin plating, water washing, and plate removal. The thin layer of chemical copper is protected by the electroplating copper and tin process to prevent the chemical copper from being eroded by acid after oxidation. The chemical copper is added to a certain extent by electroplating to remove the oxide, ink residue, and glue on the copper surface, ensuring the bonding force between the copper and the pattern electroplated with copper or nickel. The acid immersion electroplating copper and tin time should not be too long to prevent PCB surface oxidation. The acid solution should be replaced in time when it becomes turbid or the copper content is too high to prevent contamination of the electroplating copper tank and the surface of the plate.

[0033] The alkaline etching treatment in step three is to use chemical reaction method to etch and remove the copper layer in non-circuit part. The alkaline etching treatment method is to first etch the copper surface without resist layer protection by alkaline ammonium chloride copper solution, and then remove the resist layer according to the type of PCB panel by different processing methods. The alkaline etching treatment uses the resist performance of dry film, wet film, tin layer and nickel metal layer to protect the effective pattern part. After removing the resist layer, the required pattern circuit is obtained. The PCB alkaline etching process flow includes etching, sub-liquid cleaning, water washing, film removal, water washing, anti-oxidation, secondary water washing, drying, film removal, film removal water washing, medium pressure water washing, and drying. The copper foil outside the conductive circuit is removed.

[0034] The automatic optical inspection (AOI) process is to optically read the reflected light of the PCB panel substrate by a lens, and then calculate by a computer to detect suspected defects. The solder mask process is to remove the oxidation and impurities on the surface of the PCB panel substrate by chemical acid washing, mechanical brushing and sand blasting, to roughen the copper surface and increase the contact area of the PCB panel substrate surface with the solder resist. The automatic optical inspection (AOI) process can optically read the reflected light of the substrate by a lens, and then calculate by a computer to detect potential suspected defects, which can reduce the burden of inspectors, to ensure the electrical function of the PCB board and the reliability of the PCB board. The solder mask process controls the appearance and hole of the PCB board, makes the PCB board look more comfortable, and plays an insulating protection role, controls the quality of the hole, prevents short circuit caused by wave soldering, saves the amount of soldering, and prevents external mechanical damage to maintain good insulation of the board surface and increase the importance of the insulating properties of the solder resist, to ensure the quality of the PCB board.

[0035] The electroplating nickel gold process is used to improve the wear resistance of the PCB panel substrate and wrap the copper layer. The electrical measurement and FQC inspection are used to detect defective PCB boards. In use, the use of nickel as a barrier layer improves the wear resistance of the PCB panel substrate, and also effectively prevents the diffusion of copper ions. The use of dull nickel as an etch-resistant metal plating layer can make the PCB board meet the requirements of both hot press welding and soldering. In use, only nickel can be used as an etch-resistant plating layer without the need for a bright plating layer for hot press welding. In the production process of the PCB board, it is inevitable to cause short circuit, open circuit and electrical defects such as electric leakage due to external factors. In addition, the PCB is constantly evolving towards high density, fine pitch and multi-layer. If the defective boards are not screened out in time and allowed to flow into the process, it will inevitably cause more cost waste. The electrical measurement and FQC inspection effectively detect defective products, improve the quality of the PCB board, and provide reliability for subsequent soldering.

[0036] It will be obvious to a person skilled in the art that the application is not limited to the details of the foregoing exemplary embodiments and can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. The embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. No reference signs in the claims should be considered as limiting the scope of the claims to the identity of the reference signs therein.

[0037] Furthermore, it should be understood that although the description is made on the basis of the embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A method for enhancing the solder reliability of a BT packaged substrate PCB, comprising pre-designing and forming metallized half-holes on the PCB, characterized in that, The design process for the PCB board with metallized half-holes includes the following steps: Step 1: First, cut the packaging substrate according to the substrate specifications and cutting specifications. Cut the packaging substrate to the required size, use a grinding machine to grind the packaging substrate, and control the grinding temperature of the grinding machine between 85℃ and 95℃ to complete the material preparation. Then, drill holes in the packaging substrate to form a PCB substrate with two rows of metallized holes. Step 2: Further chemical copper plating and full-board copper plating are performed on the PCB substrate, and circuit transfer is performed. Then, copper-tin plating is performed on the pattern of the PCB substrate, and half-holes are routerd after copper-tin plating of the pattern. Step 3: Perform alkaline etching on the entire PCB substrate. After alkaline etching, perform automatic optical inspection (AOI) and solder mask treatment on the PCB substrate. Then, perform nickel-gold plating on the PCB substrate. The metallized half-hole is formed before the nickel-gold plating. After the nickel-gold plating, the nickel-gold encapsulates the entire copper layer of the PCB substrate. Step 4: Using water jet cutting, the PCB substrate is cut into individual pieces. The water jet does not need to cut into the metallized half-hole, so the plating of the metallized half-hole will not be damaged. The cut PCB substrate forms a nickel-gold-coated copper physical PCB board. After electrical testing and FQC inspection, the nickel-gold-coated copper physical PCB board is then used for soldering or packaging.

2. The method for enhancing the reliability of BT packaged substrate PCB soldering according to claim 1, characterized in that: In step one, the drilling method is laser drilling. The laser is reflected and focused by a lens and then hits the packaging substrate. The packaging substrate absorbs the laser and generates instantaneous high temperature, which ablates the copper layer and dielectric layer, creating through holes between the layers of the packaging substrate, thereby connecting the layers of the packaging substrate.

3. The method for enhancing the reliability of BT packaged substrate PCB soldering according to claim 1, characterized in that: In step two, the chemical copper plating process is used to deposit a thin layer of chemical copper onto the non-conductive hole wall substrate that has been drilled. The chemical copper plating process involves removing oil and oxides from the surface of the PCB substrate, adjusting the hole wall from a negative charge to a positive charge to adsorb colloidal palladium, and exposing the palladium nuclei. Finally, the activation of the palladium nuclei induces an autocatalytic reaction of chemical copper plating, allowing the copper plating reaction to proceed continuously, and covering the hole wall with a layer of chemical copper.

4. The method for enhancing the reliability of BT packaged substrate PCB soldering according to claim 3, characterized in that: The full-board copper plating process is used to protect the thin layer of chemical copper formed by the chemical copper plating process. The full-board copper plating process is as follows: after removing the oil and rust from the surface of the PCB substrate, it is used as the cathode, and a pure copper plate is used as the anode. The substrate is hung in an alkaline electroplating solution containing cuprous cyanide, sodium cyanide and sodium carbonate to perform alkaline cyanide copper plating.

5. The method for enhancing the reliability of BT packaged substrate PCB soldering according to claim 3, characterized in that: The circuit transfer process is used to transfer the image on the production film to the PCB substrate. The circuit transfer process is as follows: cut the copper-clad laminate according to the size of the printed layout diagram to make it consistent with the actual circuit diagram size, keep the copper-clad laminate clean, and print the circuit on the copper-clad laminate.

6. The method for enhancing the reliability of BT packaged substrate PCB soldering according to claim 3, characterized in that: Electroplating copper and tin on the PCB substrate pattern is used to electroplat a copper layer and a tin layer of required thickness on the exposed copper skin or hole wall of the circuit pattern. The electroplating copper and tin process is as follows: board mounting, degreasing, secondary water washing, micro-etching, water washing, acid washing, copper plating, water washing, acid immersion, tin plating, water washing, and board unmounting.

7. The method for enhancing the reliability of BT packaged substrate PCB soldering according to claim 1, characterized in that: The alkaline etching process in step three involves using a chemical reaction method to etch away the copper layer in non-circuit areas. The alkaline etching process first involves etching away the copper surface without resist layer protection using an alkaline copper chloride solution, and then removing the resist layer using different processing methods depending on the type of PCB substrate.

8. The method for enhancing the reliability of BT packaged substrate PCB soldering according to claim 7, characterized in that: The automated optical inspection (AOI) process uses an optical method, with a lens reading the reflected light from the PCB substrate, and then a computer calculates the data to detect suspected defects. The solder resist treatment uses a combination of chemical pickling, mechanical brushing, and sandblasting to remove oxides and impurities from the PCB substrate surface, roughen the copper surface, and increase the contact area between the PCB substrate surface and the solder resist.

9. The method for enhancing the reliability of BT packaged substrate PCB soldering according to claim 7, characterized in that: The electroplating nickel-gold treatment is used to improve the wear resistance of the PCB substrate and to encapsulate the copper plating layer. The electrical testing and the FQC inspection are used to detect defective PCBs.

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