Copper foil for packaging and supporting electronic component and preparation method of copper foil

Abstract

The invention relates to a copper foil for packaging and supporting an electronic component and a preparation method of the copper foil, the copper foil is provided with cavities, the cavities are prepared in a pattern electroplating mode, and the cavities are distributed in an array mode. The method solves the problem that the cavity is difficult to prepare in a printed circuit board factory, especially the problems that the thick copper foil cavity is difficult to etch, and the size of the etched cavity is difficult to control.

Description

Technical Field

[0001] The invention belongs to the technical field of electrolytic copper foil processing, and particularly relates to a copper foil for electronic component packaging support and a preparation method thereof. Background Art

[0002] In recent years, with the development trend of electronic products being thin, light and small, embedded packaging technology for chips and components (ECP technology) has developed rapidly. In the past, chips and passive devices needed to be mounted on the surface of the motherboard or packaging substrate, occupying a large amount of space on the motherboard surface. The embedded packaging substrate technology embeds chips and components into the printed circuit board, reducing the wiring length and improving the wiring density of the printed circuit board; reducing the chip and device patch solder joints and improving the reliability of the package; packaging chips and devices in the board shortens the interconnection distance between components and improves the electrical performance of the overall module. Due to the advantages of high density, high reliability and excellent electrical performance of embedded packaging substrate technology, the demand in packaging fields such as consumer electronics and power devices is gradually increasing.

[0003] As an integrated circuit, power chip plays a power control function and is in great demand in electronic equipment and power systems. When power chips are buried in packaging substrates or printed circuit boards, chip heat dissipation becomes a challenge that cannot be ignored. There are currently three mainstream solutions in the industry. The first is to use a large number of blind holes to electroplate copper pillars on the chip pads, and dissipate heat through excellent thermal conductive material metal copper; the second is to use high heat dissipation insulating materials to dissipate heat through thermal conductive insulating materials; the third is to use a large amount of copper as the main material of the printed circuit board, replacing the commonly used insulating materials as the core board, to support components and dissipate heat (such as CN110225646A).

[0004] The third solution currently used is to use copper as the core board of the printed circuit board. Thick copper foil is often used by the printed circuit board factory to wet etch and process it to make a cavity for embedding components, and then the chips and devices are placed in the cavity. However, printed circuit boards are mostly produced in board-level sizes (common sizes are 16*20 inches, 20*24 inches, etc.), and the copper foil size is too small to match the existing equipment of the printed circuit board factory, resulting in it being unusable. At present, printed circuit board factories mostly use a whole sheet of thick copper foil as raw material, process the thick copper foil by wet etching, and etch a cavity of suitable size on the copper foil to place chips and components. When the thickness of chips and components is thick, sometimes copper foil with a thickness of more than 6oz (210μm) is required. Because the copper foil is very thick, multiple etching methods are usually used. The etching parameters are difficult to control during etching, and the dimensional accuracy of the etching cavity is also difficult to control, and the requirements for the etching line body are strict. In addition, since there are not only chips buried in the cavity, but also some capacitors and resistors, some of which are small in size (0201 components are only 500*300μm), it is difficult to etch small cavities. In order to etch out the cavity for placing the device, it is necessary to compensate at the four corners of the cavity, making the cavity irregular and increasing its volume. Insulating materials need to be used to fill the cavity in later processing. Irregular cavities increase the difficulty of filling (such as Figure 1 ); At the same time, the flow of insulating materials during filling will cause the device to shift, the cavity to be irregular, and the shift pattern to be difficult to control, affecting the subsequent process processing. At present, there is no report on the use of copper foil with cavity in board-level size for embedded component technology. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a copper foil for electronic component packaging support and a preparation method thereof. No need for the printed circuit board factory to use wet etching to process the cavity, a new solution is provided for the copper foil with cavity, and the difficult problem encountered by the printed circuit board factory when embedding the power chip is solved.

[0006] The present invention provides a copper foil for electronic component packaging support, wherein the copper foil has a cavity (such as Figure 2 As shown), the cavities are prepared by pattern electroplating, and the cavities are distributed in an array. Figure 3 As shown, four cavities form a unit (depending on the design requirements, there may be one or more cavities in a unit), and multiple unit arrays are distributed on the entire copper foil.

[0007] Preferably, the copper foil has a size in the range of 300*300mm-660*660mm; a thickness in the range of 90μm-500μm; and a roughness Rz of at least one side surface <1.5μm.

[0008] Preferably, when the copper foil is viewed from above, the plane size of the cavity is within 0.01 mm. 2 -100mm2 The length and width of the cavity are 100 μm-500 μm larger than the length and width of the component; the shape of the cavity is one or more of square, rectangular, circular, and elliptical.

[0009] like Figure 3 As shown, the present invention also provides a method for preparing a copper foil for electronic component packaging support, comprising the following steps:

[0010] (1) coating a photosensitive insulating resin or a photosensitive insulating resin dry film on the surface of a titanium plate, curing the photosensitive insulating resin at a specific position using ultraviolet light, and removing the uncured photosensitive insulating resin by developing, cleaning, and obtaining a titanium plate with photosensitive resin cured at a specific position; (2) fixing the titanium plate in an electrolyte as a cathode for pattern electroplating to obtain an electroplated copper foil;

[0011] (3) single-sided grinding is performed on the surface of the electroplated copper foil, and then the copper foil is separated from the surface of the titanium plate, and the photosensitive resin is cleaned and removed to obtain a copper foil with a cavity; the copper foil is cut, and an anti-oxidation layer is deposited on the surface of the copper foil to obtain a copper foil for electronic component packaging support.

[0012] Preferably, the roughness of one side of the surface of the titanium plate in step (1) is between 0.8 μm and 1.5 μm.

[0013] Preferably, the cleaning in step (1) is carried out using a weak alkaline solution.

[0014] Preferably, the specific positions in step (1), i.e., the subsequent cavity positions, are arranged in an array on the surface of the titanium plate.

[0015] Preferably, the electrolyte in step (2) consists of copper sulfate, sulfuric acid, additives and chloride ions.

[0016] Preferably, the pattern electroplating temperature in step (2) is 40-80°C and the current density is 25-100A / dm 2 .

[0017] Preferably, step (1) and step (2) may be performed once or multiple times.

[0018] Preferably, the single-side grinding in step (3) is performed by a ceramic brush plate, a flattening brush plate or a grinding plate, so that the surface roughness of the copper foil reaches Rz<6.0μm.

[0019] Preferably, the photosensitive resin in step (3) is cleaned by using a strong alkaline solution.

[0020] The principle of the present invention is to first solidify the surface of the titanium plate with insulating resin at the desired cavity position to prevent the electroplating of metal copper at the cavity position; and then perform pattern electroplating at the position without insulating resin, and remove the insulating resin after the electroplating is completed, so as to prepare a copper foil with a cavity of a specific size. In the process, the roughness of the copper foil fur surface away from the titanium plate surface is reduced by grinding, and the roughness of a certain surface of the thick copper is prevented from being too large, which affects the processing process of embedded packaging and printed circuit board products.

[0021] The graphic electroplating method of the present invention refers to a method of shielding the positions that do not need to be electroplated with insulating resin on the surface of the electroplated cathode titanium plate, and then thickening the positions that need to be electroplated with electroplating deposition. It is an additive electroplating method. After the additive electroplating method is completed, it is only necessary to remove the insulating layer to obtain the required graphic circuit or cavity, and there is no need to wet-etch the copper foil. Therefore, the cavity size and shape are well selectable, the design space is large, and the cavity size and shape have a large range of options. Since the preparation method does not have a process of wet etching copper, the cavity size accuracy is higher, the size controllability is better, and the size consistency is better.

[0022] Beneficial Effects

[0023] The cavity position of the copper foil of the present invention is shielded by insulating resin, and the copper foil is thickened by graphic electroplating, and finally the insulating resin is removed to complete the preparation. The insulating resin is fixed by ultraviolet light curing, and the insulating layer of the light-cured shielding is easy to design, so the cavity shape is easy to design and can be designed into any shape. Since the insulating resin is fixed by ultraviolet light curing, the cavity size is easy to design, and a cavity of any size can be designed by ultraviolet light curing resin. The electroplating thickening method is graphic electroplating, which belongs to the additive electroplating method. It does not have the problem of wet etching side etching, and the cavity has good dimensional accuracy and stability, and good dimensional consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A structural diagram of chips and components embedded in a package substrate or printed circuit board.

[0025] Figure 2 Top view of the copper foil cavity produced by etching.

[0026] Figure 3 The present invention is a flow chart of the preparation of the copper foil. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0028] Example 1

[0029] This embodiment relates to a method for preparing a copper foil for electronic component packaging support, and the specific solution process is as follows:

[0030] Step A: Prepare a titanium plate, take a titanium plate as the cathode for electroplating copper foil, the size of the titanium plate is 20.4*24.4 inches. One side of the titanium plate is polished, and its roughness Rz is 1.0μm, which is convenient for peeling after electroplating copper foil and controlling the surface roughness of the copper foil.

[0031] Step B: The insulating layer is fixed on the surface of the titanium plate, and a layer of photosensitive insulating resin dry film is pressed on the surface of the titanium plate. The dry film thickness is 200 μm, the lamination temperature is 100°C, the lamination pressure is 0.5 MPa, and the lamination time is 10 seconds.

[0032] Step C: The insulating layer is cured to shield the titanium plate at the cavity position. The photosensitive insulating resin at the specific position is cured by ultraviolet light. The equipment is an LDI exposure machine. The curing position can be set directly through software editing. These positions are the subsequent cavity positions, which are arranged in an array on the surface of the titanium plate.

[0033] Step D: Remove the excess insulating layer on the titanium plate surface by development, and remove the uncured photosensitive insulating resin by development and cleaning with 1wt% sodium carbonate aqueous solution. After development, check whether the verticality of the insulating layer resin is qualified, and it cannot be incompletely developed or overdeveloped.

[0034] Step E: The titanium plate with the photosensitive resin cured at a specific position is fixed and placed in an electrolyte. The electrolyte is composed of copper sulfate, sulfuric acid, ppm-level additives (collagen or gelatin), and Cl ions. The top of the titanium plate is clamped with a clamp, and the surface of the titanium plate is energized through the clamp. The titanium plate with the photosensitive insulating resin cured is used as the cathode for pattern electroplating. At this time, the side of the titanium plate with the photosensitive insulating resin cured has another titanium plate or titanium mesh as the anode. The thickness of the electroplated copper is 200μm.

[0035] The electroplating process parameters are as follows:

[0036] Copper concentration: 90-100g / L;

[0037] Sulfuric acid concentration: 110-120g / L;

[0038] Chloride ion concentration: <30mg / L;

[0039] Additive concentration: <20mg / L;

[0040] Temperature: 50℃;

[0041] Current density: 70A / dm 2 .

[0042] Step F: Grinding the surface: Grind the electroplated surface on one side, and grind the electroplated copper foil and the surface of the photosensitive insulating material together with a ceramic brush plate to a level of Rz2.0μm.

[0043] Step G: The copper foil is peeled off from the surface of the cathode titanium plate, and the copper foil is separated from the surface of the titanium plate by mechanical means.

[0044] Step H: Stripping the insulating resin, using a 3wt% sodium hydroxide aqueous solution (temperature 60°C) to clean and remove the photosensitive insulating resin layer. At this time, the solution strips the film from both sides of the copper foil at the same time, and the reaction is faster.

[0045] Step I: Cut the copper foil. Use a cutting machine to cut the copper foil into a size of 20*24 inches.

[0046] Step J: Anti-oxidation treatment: using chemical methods to deposit a layer of metal Cr on the surface of the copper foil as an anti-oxidation component.

[0047] Example 2

[0048] This embodiment relates to a method for preparing a copper foil for electronic component packaging support, and the specific solution process is as follows:

[0049] Step A: Prepare a titanium plate, take a titanium plate as the cathode of the electroplated copper foil, the size of the titanium plate is 16.5*20.5 inches. One side of the titanium plate is polished, and its roughness Rz is 1.0μm, which is convenient for peeling after electroplating copper foil and controlling the surface roughness of the copper foil.

[0050] Step B: The insulating layer is fixed on the surface of the titanium plate, and a layer of photosensitive insulating resin dry film is pressed on the surface of the titanium plate. The dry film thickness is 200 μm, the lamination temperature is 100°C, the lamination pressure is 0.5 MPa, and the lamination time is 10 seconds.

[0051] Step C: Continue to fix the insulating layer on the surface of the titanium plate, and then press a layer of photosensitive insulating resin dry film. The dry film thickness is 200μm, the lamination temperature is 100℃, the lamination pressure is 0.5MPa, and the lamination time is 10s. At this time, the total dry film thickness on the cathode titanium plate surface is 400μm.

[0052] Step D: The insulating layer is cured to shield the titanium plate at the cavity position. The photosensitive insulating resin at the specific position is cured by ultraviolet light. The equipment is an LDI exposure machine. The curing position can be set directly through software editing. These positions are the subsequent cavity positions, which are arranged in an array on the surface of the titanium plate.

[0053] Step E: Remove the excess insulating layer on the titanium plate surface by development, and remove the uncured photosensitive insulating resin by development and cleaning with 1wt% sodium carbonate aqueous solution. After development, check whether the verticality of the insulating layer resin is qualified, and it cannot be incompletely developed or overdeveloped.

[0054] Step F: The titanium plate with the photosensitive resin cured at a specific position is fixed and placed in an electrolyte, which is composed of copper sulfate, sulfuric acid, ppm-level additives (collagen or gelatin) and Cl ions. The top of the titanium plate is clamped with a clamp, and the surface of the titanium plate is energized through the clamp. The titanium plate with the photosensitive insulating resin cured is used as the cathode for pattern electroplating. At this time, the side of the titanium plate with the photosensitive insulating resin cured has another titanium plate or titanium mesh as the anode. The thickness of the electroplated copper is 360μm.

[0055] The electroplating process parameters are as follows:

[0056] Copper concentration: 90-100g / L;

[0057] Sulfuric acid concentration: 110-120g / L;

[0058] Chloride ion concentration: <30mg / L;

[0059] Additive concentration: <20mg / L;

[0060] Temperature: 50℃;

[0061] Current density: 70A / dm 2 .

[0062] Step G: Grinding the surface: Grind the electroplated surface on one side, and grind the electroplated copper foil and the surface of the photosensitive insulating material together with a ceramic brush plate to a level of Rz2.0μm.

[0063] Step H: The copper foil is peeled off from the surface of the cathode titanium plate, and the copper foil is separated from the surface of the titanium plate by mechanical means.

[0064] Step I: Remove the insulating resin by stripping. Use 3wt% sodium hydroxide aqueous solution (temperature 60°C) to clean and remove the photosensitive insulating resin layer. At this time, the solution strips the film from both sides of the copper foil at the same time, and the reaction is faster.

[0065] Step J: Cut the copper foil and use a cutting machine to cut the copper foil into a size of 16*20 inches.

[0066] Step K: Anti-oxidation treatment: using chemical methods to deposit a layer of metal Cr on the surface of the copper foil as an anti-oxidation component.

[0067] Example 3

[0068] This embodiment relates to a method for preparing a copper foil for electronic component packaging support, and the specific solution process is as follows:

[0069] Step A: Prepare a titanium plate, take a titanium plate as the cathode for electroplating copper foil, the size of the titanium plate is 20.4*24.4 inches. One side of the titanium plate is polished, and its roughness Rz is 1.0μm, which is convenient for peeling after electroplating copper foil and controlling the surface roughness of the copper foil.

[0070] Step B: The insulating layer is fixed on the surface of the titanium plate, and a layer of photosensitive insulating resin dry film is pressed on the surface of the titanium plate. The dry film thickness is 200 μm, the lamination temperature is 100°C, the lamination pressure is 0.5 MPa, and the lamination time is 10 seconds.

[0071] Step C: The insulating layer is cured to shield the titanium plate at the cavity position. The photosensitive insulating resin at the specific position is cured by ultraviolet light. The equipment is an LDI exposure machine. The curing position can be set directly through software editing. These positions are the subsequent cavity positions, which are arranged in an array on the surface of the titanium plate.

[0072] Step D: Remove the excess insulating layer on the titanium plate surface by development, and remove the uncured photosensitive insulating resin by development and cleaning with 1wt% sodium carbonate aqueous solution. After development, check whether the verticality of the insulating layer resin is qualified, and it cannot be incompletely developed or overdeveloped.

[0073] Step E: The titanium plate with the photosensitive resin cured at a specific position is fixed and placed in an electrolyte. The electrolyte is composed of copper sulfate, sulfuric acid, ppm-level additives (collagen or gelatin), and Cl ions. The top of the titanium plate is clamped with a clamp, and the surface of the titanium plate is energized through the clamp. The titanium plate with the photosensitive insulating resin cured is used as the cathode for pattern electroplating. At this time, the side of the titanium plate with the photosensitive insulating resin cured has another titanium plate or titanium mesh as the anode. The thickness of the electroplated copper is 180μm.

[0074] The electroplating process parameters are as follows:

[0075] Copper concentration: 90-100g / L;

[0076] Sulfuric acid concentration: 110-120g / L;

[0077] Chloride ion concentration: <30mg / L;

[0078] Additive concentration: <20mg / L;

[0079] Temperature: 50℃;

[0080] Current density: 70A / dm 2 .

[0081] Step F: Grinding the surface: Grind the electroplated surface on one side, and grind the electroplated copper foil and the surface of the photosensitive insulating material together with a ceramic brush plate to a level of Rz3.0μm.

[0082] Step G: The insulating layer is fixed on the surface of the titanium plate, and a layer of photosensitive insulating resin dry film is pressed on the surface of the titanium plate. The dry film thickness is 200 μm, the lamination temperature is 100° C., the lamination pressure is 0.5 MPa, and the lamination time is 10 seconds.

[0083] Step H: The insulating layer is cured to shield the cavity position. The photosensitive insulating resin at the shielding position in step C is cured by ultraviolet light. The equipment is an LDI exposure machine, and the curing position can be set directly through software editing. Due to the positioning accuracy, the exposure area of ​​this shielding position should be slightly larger than the position in step C, and the photosensitive insulating layer position cured in step C should be wrapped inside.

[0084] Step I: Remove the excess insulating layer on the titanium plate surface by development, and use 1wt% sodium carbonate aqueous solution to remove the uncured photosensitive insulating resin. After development, check whether the verticality of the insulating layer resin is qualified, and it cannot be incompletely developed or overdeveloped.

[0085] Step J: The titanium plate with the photosensitive resin cured at a specific position is fixed and placed in an electrolyte. The electrolyte is composed of copper sulfate, sulfuric acid, ppm-level additives (collagen or gelatin), and Cl ions. The top of the titanium plate is clamped with a clamp, and the surface of the titanium plate is energized through the clamp. The titanium plate with the photosensitive insulating resin cured is used as the cathode for graphic electroplating. At this time, on the side of the titanium plate with the photosensitive insulating resin cured, there is another titanium plate or titanium mesh as the anode. The electroplated copper thickness is 180μm. At this time, the total copper thickness on the surface of the cathode titanium plate is 360um.

[0086] The electroplating process parameters are as follows:

[0087] Copper concentration: 90-100g / L;

[0088] Sulfuric acid concentration: 110-120g / L;

[0089] Chloride ion concentration: <30mg / L;

[0090] Additive concentration: <20mg / L;

[0091] Temperature: 50℃;

[0092] Current density: 70A / dm 2 .

[0093] Step K: Grinding the surface: Grind the electroplated surface on one side, and grind the electroplated copper foil and the surface of the photosensitive insulating material together by physical grinding using a ceramic brush plate. The roughness reaches the level of Rz 2.0μm.

[0094] Step L: The copper foil is peeled off from the surface of the cathode titanium plate by mechanically separating the copper foil from the surface of the titanium plate.

[0095] Step M: Stripping the insulating resin, using a strong alkaline solution, such as a 3wt% sodium hydroxide aqueous solution (temperature 60°C) to clean and remove the photosensitive insulating resin layer. At this time, the solution strips the film from both sides of the copper foil at the same time, and the reaction is faster.

[0096] Step N: Cut the copper foil. Use a cutting machine to cut the copper foil into a size of 20*24 inches.

[0097] Step O: Anti-oxidation treatment: using a chemical method to deposit a layer of metal Cr on the surface of the copper foil as an anti-oxidation component.

Claims

1. A copper foil for electronic component packaging support, the copper foil having a cavity, characterized in that: The cavities are prepared by pattern electroplating, and the cavities are distributed in an array.

2. The copper foil for supporting electronic component packaging according to claim 1, characterized in that: The copper foil has a size in the range of 300*300mm-660*660mm; a thickness in the range of 90μm-500μm; and at least one side roughness Rz<1.5μm.

3. The copper foil for supporting electronic component packaging according to claim 1, characterized in that: The plane size of the cavity is 0.01 mm 2 -100mm 2 The length and width of the cavity are 100 μm-500 μm larger than the length and width of the component; the shape of the cavity is one or more of square, rectangular, circular, and elliptical.

4. A method for preparing a copper foil for electronic component packaging support, comprising the following steps: (1) coating a photosensitive insulating resin or a photosensitive insulating resin dry film on the surface of a titanium plate, curing the photosensitive insulating resin at a specific position by ultraviolet light, and removing the uncured photosensitive insulating resin by developing and cleaning to obtain a titanium plate with the photosensitive resin cured at the specific position; (2) fixing the titanium plate in an electrolyte as a cathode for pattern electroplating to obtain an electroplated copper foil; (3) grinding the surface of the electroplated copper foil on one side, then separating the copper foil from the surface of the titanium plate, and cleaning and removing the photosensitive resin to obtain a copper foil with a cavity; The copper foil is cut and an anti-oxidation layer is deposited on the surface of the copper foil to obtain the copper foil for electronic component packaging support.

5. The preparation method according to claim 4, characterized in that: The roughness of one side of the titanium plate surface in step (1) is between 0.8 μm and 1.5 μm.

6. The preparation method according to claim 4, characterized in that: The cleaning in step (1) is performed using a weak alkaline solution.

7. The preparation method according to claim 4, characterized in that: The electrolyte in step (2) consists of copper sulfate, sulfuric acid, additives and chloride ions.

8. The preparation method according to claim 4, characterized in that: The single-side grinding in step (3) is performed by a ceramic brush plate, a flattening brush plate or a grinding plate, so that the surface roughness of the copper foil reaches Rz < 6.0 μm.

9. The preparation method according to claim 4, characterized in that: The photosensitive resin in step (3) is cleaned with a strong alkaline solution.

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