A PCB board for chip testing with ultra-thick copper steps and its fabrication method

Abstract

This application discloses an ultra-thick copper stepped chip test PCB board, comprising a copper substrate, a thermally conductive PP sheet, and a 100Z circuit layer stacked sequentially from bottom to top. The circuit layer has multiple stepped grooves for chip testing, and the stepped grooves are connected to the circuits on the PCB board for inserting gold fingers into slots. This application also discloses a method for manufacturing the ultra-thick copper stepped chip test PCB board. The beneficial effects of this application are as follows: it facilitates the control of the outer layer etching linewidth tolerance, and allows for adjustment of the compensation amount for dense lines and independent lines, adjusting etching parameters to achieve precise etching, ensuring etching uniformity and tolerance consistency. The ultra-thick copper plate adds a mesh process to the inner layer to ensure increased bonding force with the prepreg during lamination, avoiding abnormalities such as insufficient adhesive and delamination during lamination.

Description

Technical Field

[0001] This application belongs to the field of circuit board manufacturing technology, specifically relating to an ultra-thick copper-step chip test PCB board and its manufacturing method. Background Technology

[0002] A chip refers to a silicon wafer containing integrated circuits. It is very small and often part of a computer or other electronic device. As chips in consumer electronics become smaller and cost pressures increase, wafer-level chip packaging will be increasingly used in chip products. Chips are highly complex, and to ensure their reliability before leaving the factory, they need to undergo testing to ensure functional integrity. Different chip boards use different test PCBs, and the performance requirements of the PCBs vary depending on the chip's testing requirements.

[0003] To achieve the above objectives, this utility model provides an ultra-thick copper stepped chip testing PCB board. It addresses several key technical challenges in the manufacturing process of this ultra-thick copper stepped chip testing board, pushing the limits of traditional manufacturing processes. These challenges include: engineering design of the ultra-thick copper plate, engineering design of the stepped plate, lamination uniformity, etching tolerance control and uniformity of the ultra-thick copper plate, laser overprinting, screen printing ink, and appearance quality control. The main technical difficulties of this PCB board include:

[0004] (1) The copper thickness of the circuit is 10OZ and the line width / spacing is relatively dense. The tolerance requirements for line width and gold finger are + / - 5%.

[0005] (2) The stepped groove must be free of excess glue and the bottom must be very flat;

[0006] (3) The copper thickness of the circuit is too thick, and the solder mask circuit will turn yellow.

[0007] (4) The heat dissipation requirements of the entire PCB board are very high;

[0008] (5) After being subjected to a heat shock at 288℃ for 10 seconds, no stratification or bubbling occurred after 3 times. Summary of the Invention

[0009] The purpose of this application is to provide an ultra-thick copper-step chip test PCB board and its preparation method, which can solve at least one technical problem involved in the background art.

[0010] To solve the above-mentioned technical problems, this application is implemented as follows:

[0011] A PCB board for chip testing with ultra-thick copper steps includes a copper substrate, a thermally conductive PP sheet, and a 100Z circuit layer stacked from bottom to top. The circuit layer has multiple step grooves for chip testing, and the step grooves are connected to the circuits on the PCB board for inserting gold fingers into card slots.

[0012] Optionally, the PCB board is also provided with multiple mounting holes for fixing the PCB board to the device.

[0013] Optionally, the number of fixing holes is 9, with a diameter of 3.2 mm.

[0014] Optionally, the number of stepped grooves is 40, each 3*3mm in size, and each stepped groove corresponds to testing one chip.

[0015] Optionally, the gold fingers are made using a hard gold plating process with a gold thickness of 2µm.

[0016] This application also provides a method for preparing the ultra-thick copper step chip test board PCB board, including:

[0017] Step S1: Fabricate a 10OZ circuit layer. Etch copper to a depth of 5OZ on the inner layer of the 10OZ circuit layer. Specifically, this includes:

[0018] Step S11: Cut and grind the edges of the material, and cut it into 10OZ copper foil according to the design dimensions;

[0019] Step S12: Drilling holes, including tool holes, target holes, riveting holes, and positioning holes;

[0020] Step S13: Pattern transfer, apply photosensitive material to the board, perform selective exposure using LDI equipment to form circuit patterns on the photosensitive film, and remove the required non-circuit photosensitive material using a weak alkaline chemical solution.

[0021] Step S14: Etch to remove film, etch to a depth of 5 oz, use a strong oxidizing chemical to remove the exposed copper layer, and then use a strong alkaline chemical to remove all photosensitive material.

[0022] Step S2: Pressing and creating the master card flow, specifically including:

[0023] Step S21: Cut the material and grind the edges, cut the material according to the design dimensions, and cut the copper base to 1.6mm;

[0024] Step S22: Drilling holes, including tool holes, target holes, riveting holes, and positioning holes;

[0025] Step S23: Pattern transfer, apply photosensitive material to the board, perform selective exposure using LDI equipment to form circuit patterns on the photosensitive film, and remove the required non-circuit photosensitive material using a weak alkaline chemical solution.

[0026] Step S24: Etching and film removal. Etch a grid to a depth of 10µm, remove the exposed copper layer using a strong oxidizing chemical solution, and then remove all photosensitive materials using a strong alkaline chemical solution.

[0027] Step S25: PP sheet with PI film. One side of a PP sheet is covered with PI film. Laser cutting is used to leave the step pattern on the PP sheet for making the steps.

[0028] Step S26: Browning, removing grease and dirt from the board surface, roughening the copper surface to increase the bonding area between the copper surface and the prepreg;

[0029] Step S27: Lamination. Using a traditional press with constant temperature and pressure, the core boards are bonded together with a prepreg. Release films are placed on the top and bottom of the boards, and special pressing parameters are used to press together the 1.6mm copper base, PP sheet and 10OZ circuit layer into a whole.

[0030] Step S28: Drilling target holes. Use a CCD target drilling machine to drill the required positioning holes for the outer layer and drill the target holes for the inner layer.

[0031] Step S29: Mill the frame to remove the irregularly shaped frame of the board;

[0032] Step S210: Pattern transfer, apply photosensitive material to the board, perform selective exposure using LDI equipment to form circuit patterns on the photosensitive film, and remove the required non-circuit photosensitive material using a weak alkaline chemical solution.

[0033] Step S211: Etching and film removal. Etch the outer circuit pattern, remove the exposed copper layer using a strong oxidizing chemical solution, and then remove all photosensitive materials using a strong alkaline chemical solution.

[0034] Step S212: Laser shaping. Laser depth control cutting is performed from the top surface downwards. After burning around the surface, the cover is removed to expose the bottom copper base.

[0035] Step S213: Remove adhesive. Use chemical adhesive removal methods to remove residual adhesive from the surface, ensuring that the step surface is free of organic contamination.

[0036] Step S214: Solder resist fabrication. The solder resist is fabricated using a screen printing method to cover the step PAD. A second screen printing and one exposure are used to screen print the photosensitive solder resist material onto the board. Selective exposure is used with film. The photosensitive material on the required solder pads is removed by a weak alkaline chemical solution, and the green oil is cured.

[0037] Step S215: Gold-plated fingers. According to customer requirements, 2µm gold is plated on the gold finger area, and other circuit areas are protected with a film.

[0038] Step S216: Nickel-palladium-gold, peel off the previous film, then apply a protective film to the gold fingers, and perform nickel-palladium-gold surface treatment on the circuit area.

[0039] Step S217: Shape processing, cut out the required shape, and bevel the gold finger area;

[0040] Step S218: Testing, using a tester to test the electrical performance between each network;

[0041] Step S219: Finished product inspection. Visually inspect the appearance of the panels. Once they are OK, put them into storage.

[0042] Optionally, in step S218, the electrical performance includes open / short circuit, resistance, and inductance.

[0043] The beneficial effects of this invention are as follows:

[0044] (1) In order to ensure the line width tolerance, the 10OZ line layer is etched with a copper thickness of 5OZ in the inner layer. After lamination, the remaining 5OZ copper thickness is etched in the outer layer. This makes it easier to control the line width tolerance of the outer layer etching, and adjust the compensation amount of dense lines and independent lines, adjust the etching parameters, achieve precise etching, and ensure the uniformity of etching and the consistency of tolerance.

[0045] (2) The gold fingers are made by pulling a lead wire at the tip of the finger and removing the lead wire at the back edge to ensure the integrity of the finger.

[0046] (3) PI film is used to prevent glue overflow at the step position, repair scratches and ensure flatness.

[0047] (4) To solve the problem of yellowing of the circuit, multiple screen printing of solder resist is used to ensure the thickness of the solder resist ink.

[0048] (5) In order to maximize heat dissipation requirements, a 1.6mm copper substrate is used at the bottom and a high thermal conductivity PP sheet is used in the middle.

[0049] (6) The ultra-thick copper plate has an added mesh process in the inner layer to ensure increased bonding force with the prepreg during lamination and avoid abnormalities such as insufficient glue and delamination during lamination. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the structure of the ultra-thick copper step chip test board PCB provided in the embodiments of this application;

[0051] Figure 2 This is a structural diagram of the actual product of the ultra-thick copper step chip test board PCB board manufactured using the manufacturing method of the ultra-thick copper step chip test board PCB board provided in the embodiments of this application. Detailed Implementation

[0052] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0053] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0054] The following is in conjunction with the appendix Figure 1 and 2 The ultra-thick copper step chip test board PCB provided in this application will be described in detail through specific embodiments and application scenarios.

[0055] This application provides an ultra-thick copper step chip test PCB board, which includes a copper substrate 1, a thermally conductive PP sheet 2 and a 100Z circuit layer 3 stacked from bottom to top. The circuit layer 3 is provided with a plurality of step grooves 31 for chip testing. The step grooves 31 are connected to the circuits of the gold fingers 4 on the PCB board for inserting card slots.

[0056] The PCB board is also provided with multiple mounting holes 5 for fixing the PCB board to the device. Specifically, there are 9 mounting holes 5, each with a diameter of 3.2 mm.

[0057] The number of stepped grooves 31 is 40, and the size is 3*3mm. Each stepped groove 31 corresponds to one chip for testing.

[0058] The gold fingers are made using a hard gold plating process, with a gold thickness of 2µm.

[0059] This application also provides a method for preparing the ultra-thick copper step chip test board PCB board, including:

[0060] Step S1: Fabricate a 10OZ circuit layer. Etch copper to a depth of 5OZ on the inner layer of the 10OZ circuit layer. Specifically, this includes:

[0061] Step S11: Cut and grind the edges of the material, and cut it into 10OZ copper foil according to the design dimensions;

[0062] Step S12: Drilling holes, including tool holes, target holes, riveting holes, and positioning holes;

[0063] Step S13: Pattern transfer, apply photosensitive material to the board, perform selective exposure using LDI equipment to form circuit patterns on the photosensitive film, and remove the required non-circuit photosensitive material using a weak alkaline chemical solution.

[0064] Step S14: Etch to remove film, etch to a depth of 5 oz, use a strong oxidizing chemical to remove the exposed copper layer, and then use a strong alkaline chemical to remove all photosensitive material.

[0065] Step S2: Pressing and creating the master card flow, specifically including:

[0066] Step S21: Cut the material and grind the edges, cut the material according to the design dimensions, and cut the copper base to 1.6mm;

[0067] Step S22: Drilling holes, including tool holes, target holes, riveting holes, and positioning holes;

[0068] Step S23: Pattern transfer, apply photosensitive material to the board, perform selective exposure using LDI equipment to form circuit patterns on the photosensitive film, and remove the required non-circuit photosensitive material using a weak alkaline chemical solution.

[0069] Step S24: Etching and film removal. Etch a grid to a depth of 10µm, remove the exposed copper layer using a strong oxidizing chemical solution, and then remove all photosensitive materials using a strong alkaline chemical solution.

[0070] Step S25: PP sheet with PI film. One side of a PP sheet is covered with PI film. Laser cutting is used to leave the step pattern on the PP sheet for making the steps.

[0071] Step S26: Browning, removing grease and dirt from the board surface, roughening the copper surface to increase the bonding area between the copper surface and the prepreg;

[0072] Step S27: Lamination. Using a traditional press with constant temperature and pressure, the core boards are bonded together with a prepreg. Release films are placed on the top and bottom of the boards, and special pressing parameters are used to press together the 1.6mm copper base, PP sheet and 10OZ circuit layer into a whole.

[0073] Step S28: Drilling target holes. Use a CCD target drilling machine to drill the required positioning holes for the outer layer and drill the target holes for the inner layer.

[0074] Step S29: Mill the frame to remove the irregularly shaped frame of the board;

[0075] Step S210: Pattern transfer, apply photosensitive material to the board, perform selective exposure using LDI equipment to form circuit patterns on the photosensitive film, and remove the required non-circuit photosensitive material using a weak alkaline chemical solution.

[0076] Step S211: Etching and film removal. Etch the outer circuit pattern, remove the exposed copper layer using a strong oxidizing chemical solution, and then remove all photosensitive materials using a strong alkaline chemical solution.

[0077] Step S212: Laser shaping. Laser depth control cutting is performed from the top surface downwards. After burning around the surface, the cover is removed to expose the bottom copper base.

[0078] Step S213: Remove adhesive. Use chemical adhesive removal methods to remove residual adhesive from the surface, ensuring that the step surface is free of organic contamination.

[0079] Step S214: Solder resist fabrication. The solder resist is fabricated using a screen printing method to cover the step PAD. A second screen printing and one exposure are used to screen print the photosensitive solder resist material onto the board. Selective exposure is used with film. The photosensitive material on the required solder pads is removed by a weak alkaline chemical solution, and the green oil is cured.

[0080] Step S215: Gold-plated fingers. According to customer requirements, 2µm gold is plated on the gold finger area, and other circuit areas are protected with a film.

[0081] Step S216: Nickel-palladium-gold, peel off the previous film, then apply a protective film to the gold fingers, and perform nickel-palladium-gold surface treatment on the circuit area.

[0082] Step S217: Shape processing, cut out the required shape, and bevel the gold finger area;

[0083] Step S218: Testing, using a tester to test the electrical performance between each network;

[0084] Step S219: Finished product inspection. Visually inspect the appearance of the panels. Once they are OK, put them into storage.

[0085] Optionally, in step S218, the electrical performance includes open / short circuit, resistance, and inductance.

[0086] The beneficial effects of this invention are as follows:

[0087] (1) In order to ensure the line width tolerance, the 10OZ line layer is etched with a copper thickness of 5OZ in the inner layer. After lamination, the remaining 5OZ copper thickness is etched in the outer layer. This makes it easier to control the line width tolerance of the outer layer etching, and adjust the compensation amount of dense lines and independent lines, adjust the etching parameters, achieve precise etching, and ensure the uniformity of etching and the consistency of tolerance.

[0088] (2) The gold fingers are made by pulling a lead wire at the tip of the finger and removing the lead wire at the back edge to ensure the integrity of the finger.

[0089] (3) PI film is used to prevent glue overflow at the step position, repair scratches and ensure flatness.

[0090] (4) To solve the problem of yellowing of the circuit, multiple screen printing of solder resist is used to ensure the thickness of the solder resist ink.

[0091] (5) In order to maximize heat dissipation requirements, a 1.6mm copper substrate is used at the bottom and a high thermal conductivity PP sheet is used in the middle.

[0092] (6) The ultra-thick copper plate has an added mesh process in the inner layer to ensure increased bonding force with the prepreg during lamination and avoid abnormalities such as insufficient glue and delamination during lamination.

[0093] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are within the protection of this application.

Claims

1. A method for fabricating an ultra-thick copper-step chip test PCB, characterized in that, include: Step S1: Fabricate a 10OZ circuit layer by etching copper to a depth of 5 OZ on the inner layer of the 10 OZ circuit layer. Specifically, this includes: Step S11: Cut and grind the edges of the material, and cut it into 10OZ copper foil according to the design dimensions; Step S12: Drilling holes, including tool holes, target holes, riveting holes, and positioning holes; Step S13: Pattern transfer, apply photosensitive material to the board, perform selective exposure using LDI equipment to form circuit patterns on the photosensitive film, and remove the required non-circuit photosensitive material using a weak alkaline chemical solution. Step S14: Etch to remove film, etch to a depth of 5 oz, use a strong oxidizing chemical to remove the exposed copper layer, and then use a strong alkaline chemical to remove all photosensitive material. Step S2: Overall lamination process, specifically including: Step S21: Cut the material and grind the edges, cut the material according to the design dimensions, and cut the copper base to 1.6mm; Step S22: Drilling holes, including tool holes, target holes, riveting holes, and positioning holes; Step S23: Pattern transfer, apply photosensitive material to the board, perform selective exposure using LDI equipment to form circuit patterns on the photosensitive film, and remove the required non-circuit photosensitive material using a weak alkaline chemical solution. Step S24: Etching and film removal. Etch a grid to a depth of 10µm, remove the exposed copper layer using a strong oxidizing chemical solution, and then remove all photosensitive materials using a strong alkaline chemical solution. Step S25: PP sheet with PI film. One side of a PP sheet is covered with PI film. Laser cutting is used to leave the step pattern on the PP sheet for making the steps. Step S26: Browning, removing grease and dirt from the board surface, roughening the copper surface to increase the bonding area between the copper surface and the prepreg; Step S27: Lamination. Using a traditional press with constant temperature and pressure, the core boards are bonded together with a prepreg. Release films are placed on the top and bottom of the board to press the 1.6mm copper base, PP sheet and 10OZ circuit layer into a whole. Step S28: Drilling target holes. Use a CCD target drilling machine to drill the required positioning holes for the outer layer and drill the target holes for the inner layer. Step S29: Mill the frame to remove the irregularly shaped frame of the board; Step S210: Pattern transfer, apply photosensitive material to the board, perform selective exposure using LDI equipment to form circuit patterns on the photosensitive film, and remove the required non-circuit photosensitive material using a weak alkaline chemical solution. Step S211: Etching and film removal. Etch the outer circuit pattern, remove the exposed copper layer using a strong oxidizing chemical solution, and then remove all photosensitive materials using a strong alkaline chemical solution. Step S212: Laser shaping. Laser depth control cutting is performed from the top surface downwards. After burning around the surface, the cover is removed to expose the bottom copper base. Step S213: Remove adhesive. Use chemical adhesive removal methods to remove residual adhesive from the surface, ensuring that the step surface is free of organic contamination. Step S214: Solder resist fabrication. The solder resist is fabricated using a screen printing method to cover the step PAD. A second screen printing and one exposure are used to screen print the photosensitive solder resist material onto the board. Selective exposure is used with film. The photosensitive material on the required solder pads is removed by a weak alkaline chemical solution, and the green oil is cured. Step S215: Gold-plated fingers. According to customer requirements, 2µm gold is plated on the gold finger area, and other circuit areas are protected with a film. Step S216: Nickel-palladium-gold, peel off the previous film, then apply a protective film to the gold fingers, and perform nickel-palladium-gold surface treatment on the circuit area. Step S217: Shape processing, cut out the required shape, and bevel the gold finger area; Step S218: Testing, using a tester to test the electrical performance between each network; Step S219: Finished product inspection. Visually inspect the appearance of the panels. Once they are OK, put them into storage.

2. The preparation method according to claim 1, characterized in that, In step S218, the electrical performance includes open / short circuit, resistance, and inductance.

3. The preparation method according to claim 1, characterized in that, The ultra-thick copper step chip test PCB board includes a copper substrate, a thermally conductive PP sheet, and a 100Z circuit layer stacked from bottom to top. The circuit layer has multiple step grooves for chip testing, and the step grooves are connected to the circuits on the PCB board for inserting gold fingers into the slots.

4. The preparation method according to claim 3, characterized in that, The PCB board also has multiple mounting holes for fixing the PCB board to the equipment.

5. The preparation method according to claim 4, characterized in that, The number of fixing holes is 9, and the diameter is 3.2mm.

6. The preparation method according to claim 3, characterized in that, The number of stepped grooves is 40, each measuring 3*3mm, and each stepped groove corresponds to the testing of one chip.

7. The preparation method according to claim 3, characterized in that, The gold fingers are made using a hard gold plating process, with a gold thickness of 2µm.

Images