High-flatness BGA circuit board and manufacturing method thereof

Abstract

The invention discloses a high-flatness BGA (Ball Grid Array) circuit board and a manufacturing method thereof. The high-flatness BGA circuit board comprises a plurality of layers of circuit carriers, a glass plate is attached between the first layer and the second layer of the multi-layer circuit carrier through an adhesive material; a through hole is formed in the glass plate, and a bonding material is injected into the through hole; and a plated-through hole is formed in the adhesive material in the through hole and is communicated with the first layer and the second layer of the multi-layer circuit carrier. According to the invention, the glass plate is installed between the first layer and the second layer of the multi-layer circuit carrier through the bonding material, so that the surface flatness problem of the HDI and the multi-layer circuit board is solved; the metalized layers of the through holes in the glass and the metalized holes in the metalized layers form a signal net-shaped shielding layer similar to a coaxial cable, a central conductor and an inner insulating layer, so that when signals are transmitted, electromagnetic interference is resisted, signal quality is kept, and signal loss is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board manufacturing, and in particular to a high-flatness BGA circuit board and a manufacturing method thereof. Background Art

[0002] BGA (Ball Grid Aarray) flatness is directly related to soldering quality and component connection stability. In high-speed data transmission, such as 22Gbps, any minor connection problem may cause signal distortion or transmission errors. Insufficient BGA flatness leads to loose soldering, which in turn causes problems such as poor contact, signal interruption or signal attenuation during high-speed data transmission.

[0003] Secondly, BGA with poor flatness will increase the uneven stress distribution of the entire circuit board. During high-speed data transmission, the circuit board and the components on it will generate heat, resulting in thermal expansion and contraction. If the BGA is not flat enough, this thermal stress may cause cracking of solder joints or component displacement, thus affecting the stability and reliability of the circuit board.

[0004] In addition, BGA flatness will also affect the overall performance of the module circuit board. Insufficient flatness may cause problems such as discontinuity or impedance mismatch in the signal lines on the circuit board, which will cause interference and loss in high-speed signal transmission, further reducing the accuracy and stability of data transmission.

[0005] Since the circuit board is formed by pressing a prepreg and a copper clad laminate, the uneven flow of the resin in the process of filling the line gap will lead to inconsistent thickness uniformity of the circuit board. The larger the area, the greater the height difference, which will cause large-size chips to crack during the packaging process or crack due to the influence of the CTE of the material during long-term use, and put higher requirements on the flatness of the PCB board. The existing technology will have problems such as PCB board warping, BGA flatness and BGA warpage during assembly, which cannot meet the technical requirements of large-size packaging, nor can it meet the requirements of product assembly efficiency, yield and product reliability. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a high-flatness BGA circuit board and a method for manufacturing the same. The present invention installs a glass plate between the first layer and the second layer of a multi-layer circuit carrier through an adhesive material, thereby solving the surface flatness problem of HDI and high-layer circuit boards.

[0007] To achieve the above object, the present invention is implemented by adopting the following technical solutions: In one aspect, the present invention provides a high-flatness BGA circuit board, comprising a multi-layer circuit carrier; The first layer and the second layer of the multi-layer circuit carrier are bonded to a glass plate by an adhesive material; The glass plate is provided with a through hole, and the through hole is filled with adhesive material; A metallized hole is provided in the adhesive material in the through hole, and the metallized hole connects the first layer and the second layer of the multi-layer circuit carrier.

[0008] Optionally, the size of the glass plate is 2-3 inches smaller than the size of the panel on one side, and the size of the glass plate is 1-2 centimeters larger than the size of the circuit area of ​​the multi-layer circuit carrier on one side.

[0009] Optionally, the diameter of the through hole is 2-8 mils larger than the diameter of the preset finished hole.

[0010] Optionally, the aperture of the metallized hole is controlled according to a preset aperture of the finished hole, and the aperture of the metallized hole is smaller than the aperture of the through hole.

[0011] In a second aspect, the present invention provides a method for manufacturing the high-flatness BGA circuit board according to the first aspect, comprising: Processing the second to last layers of the multilayer circuit carrier; Applying adhesive material on the upper surface of the first layer of the multi-layer circuit carrier, installing the lower surface of the glass plate on the upper surface of the first layer of the multi-layer circuit carrier, and the glass plate covers the circuit area of ​​the multi-layer circuit carrier; Performing laser hole burning on the glass plate to obtain through holes; Injecting adhesive material into the through hole and coating the adhesive material on the surface of the glass plate; The pasting material in the through hole is subjected to laser burning and metallization in sequence to obtain a metallized hole; The upper surface of the glass plate is mounted on the lower surface of the second layer of the multi-layer circuit carrier to obtain the high-flatness BGA circuit board.

[0012] Optionally, before manufacturing, the roughness of the surface of the glass plate is polished to be uniform; The roughness of the surface of the glass plate is polished to at least 5 microns.

[0013] Optionally, before laser burning the glass plate, a piece of kraft paper or a high temperature resistant release film is covered on the glass plate; Vacuum out the bubbles between the glass plate and the adhesive material until all the bubbles are out; According to the curing temperature of the adhesive material, the adhesive material is vacuum-baked until the adhesive material is completely cured, and the kraft paper or high temperature resistant release film is removed.

[0014] Optionally, after the glass plate is laser-burned and before the through holes are filled with adhesive material, the glass plate is sequentially subjected to high-pressure water washing and metallization.

[0015] Optionally, after the adhesive material is coated on the upper surface of the glass plate and before the adhesive material in the through hole is laser burned, a copper foil is covered on the upper surface of the glass plate, and the adhesive material is pressed at high temperature until the adhesive material is completely cured.

[0016] Optionally, the metallized hole is obtained by solid copper electroplating or single hole plating followed by injection of adhesive material.

[0017] Beneficial Effects

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention installs a glass plate between the first layer and the second layer of a multi-layer circuit carrier through an adhesive material, thereby solving the surface flatness problem of HDI and high multi-layer circuit boards; the metallized layer of the through hole on the glass plate and the metal hole therein form a signal mesh shielding layer, a center conductor and an inner insulating layer similar to a coaxial cable, so that electromagnetic interference is resisted when transmitting signals, signal quality is maintained, and signal loss is reduced; at this time, the obtained metallized hole is wrapped by the adhesive material, and the impedance of the metallized hole will not be affected by the glass plate, which can meet the technical requirements of large-size packaging, and can also meet the requirements of product assembly efficiency, yield and product reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure shows a schematic diagram of the structure of a high flatness BGA circuit board in one embodiment of the present invention; Figure 2 FIG. 1 is a schematic flow chart of a method for manufacturing a high-flatness BGA circuit board according to an embodiment of the present invention; In the figure: 1-adhesive material; 2-glass plate; 3-through hole; 4-metallized hole. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations on the technical solution of the present invention. The embodiments of the present invention and the technical features in the embodiments may be combined with each other unless there is a conflict.

[0021] The term "and / or" is only a description of the association relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " generally indicates that the related objects are in an "or" relationship.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0024] Example 1

[0025] like Figure 1 As shown, this embodiment introduces a high-flatness BGA circuit board, which specifically includes a multi-layer circuit carrier.

[0026] The first layer and the second layer of the multi-layer circuit carrier are bonded to a glass plate 2 via an adhesive material 1. The adhesive material 1 may be a resin.

[0027] In this embodiment, the size of the glass plate 2 is 2-3 inches smaller than the size of the panel on one side, and the size of the glass plate 2 is 1-2 centimeters larger than the size of the circuit area on the multi-layer circuit carrier on one side.

[0028] The glass plate 2 is provided with a through hole 3, the position of the through hole 3 is the same as the position of the preset positioning hole on the panel, and the glass hole 3 is filled with adhesive material 1. The aperture of the through hole 3 is 2-8 milliinches larger than the aperture of the preset finished product hole.

[0029] A metallized hole 4 is provided in the adhesive material in the through hole 3, and the metallized hole 4 connects the first layer and the second layer of the multi-layer circuit carrier. The diameter of the metallized hole 4 is controlled according to the preset diameter of the finished hole, and the diameter of the metallized hole 4 is smaller than the diameter of the through hole 3.

[0030] Example 2

[0031] like Figure 2 As shown, this embodiment introduces a method for manufacturing a high-flatness BGA circuit board based on the embodiment 1, which specifically includes the following steps: First, the second layer to the last layer of the multi-layer circuit carrier are processed by a traditional PCB processing technology.

[0032] In this embodiment, the glass plate 2 and the first and second layers of the circuit carrier may be manufactured first, and then the second to last layers of the circuit carrier may be processed by a conventional PCB processing technique.

[0033] Before manufacturing, the roughness of the surface of the glass plate 2 is polished to be uniform; the roughness of the surface of the glass plate 2 is polished to at least 5 microns. Sandblasting or mechanical arm sandpaper polishing can be used.

[0034] Sandblasting is a process for surface treatment of workpieces. It uses compressed air as a power source to form a high-speed jet beam to spray materials (such as copper ore sand, quartz sand, corundum, iron sand, sea sand, etc.) at high speed onto the surface of the glass plate 2, so that the appearance or shape of the surface of the glass plate 2 changes. Due to the impact and cutting action of the abrasive on the surface of the glass plate 2, the surface of the glass plate 2 acquires a certain degree of cleanliness and different degrees of roughness. Through sandblasting, a certain degree of roughness can be formed on the surface of the glass plate 2, providing a good foundation for subsequent coating, painting, electroplating and other processes.

[0035] Robotic arm sandpaper grinding refers to an automated production method that uses the end effector of the robot arm (such as a grinding head) to install sandpaper or sandpaper discs, and through the precise control and movement of the robot arm, grinds and polishes the surface of the workpiece. The robot arm can work 24 hours a day without interruption, and the grinding speed is fast, which can greatly improve production efficiency. The precise control of the robot arm and the fine grinding ability of the sandpaper can ensure the flatness, finish and consistency of the workpiece surface. Traditional manual grinding work is labor-intensive and easily affected by the working environment. Robotic arm sandpaper grinding can realize automated production and reduce the labor intensity of workers. Robotic arm sandpaper grinding can prevent workers from directly contacting grinding tools and workpieces, reducing the occurrence of work-related accidents.

[0036] The adhesive material 1 is coated on the upper surface of the first layer of the multi-layer circuit carrier.

[0037] The lower surface of the glass plate 2 is mounted on the upper surface of the first layer of the multi-layer circuit carrier, and the glass plate 2 covers the circuit area of ​​the multi-layer circuit carrier.

[0038] A piece of kraft paper or a high temperature resistant release film is covered on the glass plate 2. In this embodiment, the kraft paper or the high temperature resistant release film is 1-3 inches larger than the size of the panel on one side.

[0039] The air bubbles between the glass plate 2 and the adhesive material 1 are vacuumed out by using a vacuum laminator until all the air bubbles overflow.

[0040] According to the curing temperature of the adhesive material 1, the adhesive material 1 is vacuum-baked until the adhesive material 1 is completely cured, and the kraft paper or high-temperature resistant release film is removed.

[0041] According to the preset positioning hole positions of the panel, the glass plate 2 is laser burned to obtain the through hole 3; wherein the panel is used to protect the circuit area of ​​the multi-layer circuit carrier.

[0042] When the laser beam irradiates the surface of the glass plate 2, the energy of the laser is absorbed by the glass plate 2 and converted into heat energy, causing the local temperature of the glass plate 2 to rise and melt or vaporize, thereby forming a hole. In the laser, due to the increase in output power density, gas molecules with a specific frequency (or speed) will participate more in the stimulated radiation process, resulting in a decrease in the number of inverted particles of these molecules, thereby forming a "burned hole" on the gain curve.

[0043] After the glass plate 2 is washed with high pressure water, the glass plate 2 is metallized.

[0044] The adhesive material 1 is injected into the through hole 3 , and the adhesive material 1 is coated on the upper surface of the glass plate 2 .

[0045] A copper foil is covered on the upper surface of the glass plate 2, and the adhesive material 1 is pressed at high temperature until the adhesive material 1 is completely cured. Then the copper foil is blackened.

[0046] Laser burns the paste material 1 in the through hole 3 and then metallizes it to obtain the metallized hole 3. The diameter of the metallized hole 3 is controlled according to the preset diameter of the finished hole, and the diameter of the metallized hole 3 is smaller than the diameter of the through hole 3.

[0047] In this embodiment, the pasting material 1 in the through hole 3 may be laser burned or mechanically drilled, whichever is more appropriate according to the specific situation.

[0048] The metallized hole 3 is obtained by solid copper electroplating or single hole plating followed by injection of the adhesive material 1. The specific situation is carried out according to actual requirements.

[0049] Browning is usually removed by a specific chemical treatment to form an oxide film on the surface of the copper foil, which is used to improve the bonding strength between the copper foil and the resin layer 1. It includes the use of specific chemical treatment agents, such as sulfuric acid / hydrogen peroxide system, and other additives such as suspended copper adhesion wetting activators and selective etchants, etc., through dipping or spraying. These treatment agents can evenly remove browning while minimizing corrosion to the normal copper surface, thereby obtaining a clean copper foil surface.

[0050] The upper surface of the glass plate 2 is mounted on the lower surface of the second layer of the multi-layer circuit carrier.

[0051] The first layer and the last layer of the multi-layer circuit carrier are processed for outer layer circuits.

[0052] Then, the outer layer of the multi-layer circuit carrier is subjected to ink and surface treatment to obtain the high-flatness BGA circuit board.

[0053] Ink is mainly composed of pigments, binders, additives and solvents, and different types of inks have different ingredients. The properties of ink include color, gloss, drying speed, adhesion, abrasion resistance, weather resistance, etc. These properties directly affect the quality and use of printed products. With the improvement of environmental awareness, the environmental protection of ink has received more and more attention. As a green and environmentally friendly ink, UV ink has the characteristics of instant fast curing, no volatile organic solvents (VOC), less pollution, high efficiency and low energy consumption.

[0054] Surface treatment technology is to change the morphology, chemical composition or organizational structure of the material surface by physical or chemical methods in order to improve material performance, improve appearance or meet specific needs.

[0055] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.

Claims

1. A high flatness BGA circuit board, characterized in that: including a multi-layer circuit carrier; The first layer and the second layer of the multi-layer circuit carrier are bonded to a glass plate by an adhesive material; The glass plate is provided with a through hole, and the through hole is filled with adhesive material; A metallized hole is provided in the adhesive material in the through hole, and the metallized hole connects the first layer and the second layer of the multi-layer circuit carrier.

2. The high flatness BGA circuit board according to claim 1, characterized in that: The size of the glass plate is 2-3 inches smaller than the size of the panel on one side, and the size of the glass plate is 1-2 centimeters larger than the size of the circuit area on the multi-layer circuit carrier on one side.

3. The high flatness BGA circuit board according to claim 1, characterized in that: The aperture of the through hole is 2-8 mils larger than the aperture of the preset finished hole.

4. The high flatness BGA circuit board according to claim 3, characterized in that: The aperture of the metallized hole is controlled according to the preset aperture of the finished hole, and the aperture of the metallized hole is smaller than the aperture of the through hole.

5. A method for manufacturing a high-flatness BGA circuit board according to any one of claims 1 to 4, characterized in that: include: Processing the second to last layers of the multilayer circuit carrier; Applying adhesive material on the upper surface of the first layer of the multi-layer circuit carrier, installing the lower surface of the glass plate on the upper surface of the first layer of the multi-layer circuit carrier, and the glass plate covers the circuit area of ​​the multi-layer circuit carrier; Performing laser hole burning on the glass plate to obtain through holes; Injecting adhesive material into the through hole and coating the adhesive material on the surface of the glass plate; The pasting material in the through hole is subjected to laser burning and metallization in sequence to obtain a metallized hole; The upper surface of the glass plate is mounted on the lower surface of the second layer of the multi-layer circuit carrier to obtain the high-flatness BGA circuit board.

6. The method for manufacturing a high-flatness BGA circuit board according to claim 5, characterized in that: Before manufacturing, the roughness of the surface of the glass plate is polished uniformly; The roughness of the surface of the glass plate is polished to at least 5 microns.

7. The method for manufacturing a high-flatness BGA circuit board according to claim 5, characterized in that: Before laser hole burning is performed on the glass plate, a piece of kraft paper or a high temperature resistant release film is covered on the glass plate; Vacuum out the bubbles between the glass plate and the adhesive material until all the bubbles are out; According to the curing temperature of the adhesive material, the adhesive material is vacuum-baked until the adhesive material is completely cured, and the kraft paper or high temperature resistant release film is removed.

8. The method for manufacturing a high-flatness BGA circuit board according to claim 5, characterized in that: After the glass plate is laser-burned and before the adhesive material is inserted into the through hole, the glass plate is sequentially subjected to high-pressure water washing and metallization.

9. The method for manufacturing a high-flatness BGA circuit board according to claim 5, characterized in that: After the adhesive material is coated on the upper surface of the glass plate and before the adhesive material in the through hole is laser burned, a copper foil is covered on the upper surface of the glass plate, and the adhesive material is pressed at high temperature until the adhesive material is completely cured.

10. The method for manufacturing a high-flatness BGA circuit board according to claim 5, characterized in that: The metallized holes are obtained by solid copper electroplating or single hole plating followed by injection of adhesive material.

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