A method and processing fixture for resin plugging of large-diameter through holes in copper blocks.

Abstract

This invention provides a resin plugging method and processing fixture for large-diameter through holes in a copper block. The method includes the following steps: S1: Applying adhesive tape to the copper block to seal one end of the through hole; S2: Placing the copper block into a limiting groove on the fixture, with the side of the copper block containing the adhesive tape facing the bottom of the limiting groove; S3: Drilling vent holes through the fixture and the adhesive tape along the central axis of the through hole; S4: Pressing resin ink into the through hole through the unsealed end until the resin ink completely fills the interior of the through hole; S5: Baking the filled copper block and the fixture together at high temperature to completely cure the resin ink in the through hole. This invention solves the technical problems of incomplete resin filling and the presence of voids and air bubbles inside the resin in existing resin plugging processes for large-diameter through holes.

Description

Technical Field

[0001] This invention relates to the field of PCB manufacturing technology, and more specifically, to a resin plugging method and processing fixture for large-diameter through holes on copper blocks. Background Technology

[0002] In the manufacturing process of embedded copper circuit boards, copper blocks need to be embedded in multilayer circuit boards before lamination. The copper blocks typically have through-holes to achieve efficient heat dissipation and lightweight structure. When laminating the copper blocks with the insulating substrate and circuit layers, the through-holes must be completely filled and sealed to avoid quality defects such as insufficient adhesive in the holes, delamination, and insufficient bonding strength during lamination. Therefore, before lamination, the through-holes on the copper blocks need to be plugged with resin.

[0003] Resin plugging refers to injecting liquid resin ink into through-holes in a copper block and then curing the resin ink at high temperature to achieve full filling of the through-holes. This prevents quality problems in subsequent copper block embedding and lamination processes, ensuring stable production quality. Traditional resin plugging technology is mainly suitable for small-diameter blind hole structures. When dealing with large-diameter through-holes (>10mm) in copper blocks, the following two main problems exist: Firstly, since the through holes on the copper block are through structures at both ends, the large diameter of the holes results in a large flow area. The liquid resin itself is fluid, and with the pressure of plugging the holes plus the weight of the resin itself, it will flow directly out from the other end of the through hole, making it impossible to retain and fill the hole. Conventional plugging processes are completely impossible to implement. Secondly, even if one end of the through hole is temporarily sealed, due to the large internal volume of the large hole, when resin is inserted, the air inside the hole will be sealed inside the cavity by the resin and cannot be discharged. In the end, it will be wrapped in the resin and form large areas of voids and bubbles after curing, which completely fails to meet the quality requirement of "full and without voids". Summary of the Invention

[0004] In view of this, the present invention provides a resin plugging method and processing fixture for large-diameter through holes on copper blocks, so as to solve the common technical problems in the industry of incomplete filling and easy generation of voids and bubbles in the existing resin plugging process for large-diameter through holes on copper blocks.

[0005] The objective of this invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for resin plugging of large-diameter through holes in a copper block, wherein the copper block has at least one through hole to be plugged, and the method includes the following steps: S1: Attach adhesive tape to the copper block to seal one end of the through hole; S2: Place the copper block into the limiting groove on the fixture, and make the side of the copper block with the tape face the bottom of the limiting groove; S3: Drill a vent hole through the fixture and the tape along the central axis of the through hole; S4: Press resin ink into the through hole through the unsealed end of the through hole until the resin ink completely fills the inside of the through hole; S5: The copper block that has been filled and the fixture are baked together at high temperature to completely cure the resin ink in the through hole; The diameter of the vent hole is smaller than the diameter of the through hole.

[0006] In the above solution, by attaching tape to one side of the copper block, the through hole with both ends is converted into a blind hole structure with one end closed and the other open. This prevents the resin ink from flowing out of the other end of the through hole due to its own weight and the plugging pressure during the pressing process. At the same time, by placing the side of the copper block with tape facing the bottom of the limiting groove, the bottom of the groove can provide rigid support for the sealing tape on the entire plane. When the resin ink is pressed in, it can completely offset the downward pressure of the resin on the tape under the large diameter, avoiding failure problems such as bulging, damage, delamination, and curling of the tape due to pressure, and ensuring the stability of the resin filling process. In this process, by drilling vent holes in the fixture and tape, the air squeezed by the resin in the blind hole can be continuously and smoothly discharged to the outside through the vent holes during the resin ink pressing process in step S4, without forming air bubbles or voids in the hole. At the same time, the diameter of the vent holes is much smaller than the diameter of the through hole to be plugged. The viscosity and surface tension of the resin ink itself can be used to achieve the effect of "venting only and not leaking glue", thus taking into account both the venting performance and the requirement of preventing glue leakage. This effectively eliminates internal voids and air bubbles, achieves complete and full filling, and significantly improves the resin plugging quality of large-diameter through holes.

[0007] The limiting groove on the fixture matches the size of the copper block, providing rigid horizontal positioning and ensuring its stability during processing. Simultaneously, during resin filling, the limiting groove effectively prevents horizontal displacement of the copper block, avoiding resin ink from falling onto the copper surface in non-hole-filling areas. This eliminates the problem of resin residue on the copper surface at its source, saving the need for subsequent cleaning procedures.

[0008] Optionally, in one embodiment, the diameter of the through hole is ≥10mm.

[0009] Optionally, in one embodiment, the diameter of the vent hole is 1-3 mm.

[0010] In the above scheme, the vent hole diameter ranges from 1 to 3 mm, which is much smaller than the through hole to be plugged on the copper block. Due to the high viscosity and surface tension of the resin ink, leakage cannot occur at this vent hole diameter, and the sealing performance of the blind hole plugging structure can be maintained continuously. At the same time, the vent hole diameter is sufficiently unobstructed, and the air inside the hole can be quickly and completely discharged when plugging the hole, without the formation of air bubbles and voids due to poor air exhaust caused by the vent hole diameter being too small.

[0011] Optionally, in one embodiment, the tape is a high-temperature resistant tape.

[0012] In the above solution, the high-temperature tape can withstand the high-temperature baking during curing, effectively maintaining the seal integrity throughout the baking process, continuously and stably sealing the end face of the through hole, ensuring that the blind hole structure does not fail, and providing a reliable foundation for the full filling of large-diameter resin; in addition, the high-temperature tape has strong high-temperature stability, leaves no adhesive residue after peeling, and will not contaminate the copper surface, thereby reducing subsequent cleaning processes and simplifying the manufacturing process.

[0013] Optionally, in one embodiment, step S5 further includes grinding the surface of the copper block after curing.

[0014] In the above solution, since the resin filling and curing may be slightly higher than the surface of the through hole, or a small amount of overflow may form at the hole opening, the excess resin can be removed by grinding, so that the resin inside the hole is flush with the surface of the copper block, keeping the copper surface smooth and free of impurities, avoiding delamination and poor bonding when it is pressed with the circuit board in the future, and improving the reliability of pressing the copper block with other materials.

[0015] Secondly, the present invention provides a processing fixture, which is applied to the aforementioned resin plugging method. The processing fixture includes a fixture plate body and a limiting groove formed on the fixture plate body, the limiting groove being used to place a copper block.

[0016] In the above scheme, the limiting groove is used to achieve full-circumference rigid limiting of the copper block in the horizontal direction, to prevent the copper block from shifting during processing, and to ensure the stability of the copper block during resin filling, baking and curing and grinding.

[0017] Optionally, in one embodiment, the depth of the limiting groove is the same as the thickness of the copper block.

[0018] In the above solution, by setting the depth of the limiting groove to be the same as the thickness of the copper block, the upper surface of the copper block after being placed in the limiting groove can be precisely flush with the upper surface of the fixture plate body without any height difference. This provides a unified planar processing benchmark for drilling vent holes, resin plugging, and surface grinding, thereby improving the positional accuracy and process consistency of plugging.

[0019] Optionally, in one embodiment, the thickness of the fixture plate body is 1 mm greater than the thickness of the copper block.

[0020] Optionally, in one embodiment, the planar profile dimensions of the limiting groove are the same as the planar profile dimensions of the copper block.

[0021] In the above solution, the limiting groove is perfectly matched with the plane contour of the copper block, which can form a circumferential all-round constraint on the copper block. During the entire process of drilling the vent hole, pressing in the resin ink, high-temperature baking, and surface grinding, the copper block will not shift or shake. This fundamentally avoids problems such as drilling eccentricity, plugging and glue overflow, and grinding misalignment caused by copper block displacement, and greatly improves process positioning accuracy and product consistency.

[0022] Optionally, in one embodiment, the fixture plate body has a positioning hole on the side facing away from the limiting groove. The positioning hole is provided corresponding to the through hole on the copper block, and the central axis of the positioning hole coincides with the central axis of the through hole.

[0023] In the above scheme, the positioning hole serves as the positioning reference for drilling the vent hole in step S3. Structurally, it ensures that the drilled vent hole is precisely located at the center of the through hole on the copper block, avoiding the problems of vent hole eccentricity and offset caused by manual positioning or drilling without a reference. At the same time, using the preset positioning hole as a drilling guide eliminates the need for operators to perform additional measurement and calibration work, greatly simplifying the drilling alignment operation and improving convenience.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses adhesive tape to seal through holes on one side, transforming through holes into blind holes. This directly blocks the path of resin ink leakage due to its own weight and the pressure of the plugging hole. At the same time, the side of the copper block with the tape is facing the bottom of the limiting groove. The bottom of the groove provides full-plane rigid support for the tape, effectively offsetting the downward pressure of the resin on the tape under large hole diameter. This avoids sealing failure problems such as bulging, damage, delamination, and curling of the tape, ensuring no glue leakage throughout the plugging process and providing a basic guarantee for stable filling. This invention drills vent holes along the central axis of the through hole, penetrating the fixture and the tape. During the resin ink injection process, air inside the hole can be smoothly discharged through the vent holes, preventing it from being trapped in the resin and forming bubbles or voids. At the same time, the diameter of the vent holes is much smaller than the diameter of the through hole to be plugged. It can rely on the viscosity and surface tension of the resin ink to achieve the effect of "venting only, not leaking glue", taking into account both venting efficiency and sealing effect, so that the resin inside the hole is fully and densely filled, fundamentally improving the molding quality of resin plugging of large-diameter through holes. The process steps of this invention are simple and clear, and the fixture structure is simple. It does not require special and complex equipment and can be implemented using conventional processing and baking equipment. The operation difficulty and production cost are low. It can effectively meet the mass production needs of plugging large-diameter through holes in copper blocks and can significantly improve product yield. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the machining fixture in Example 2.

[0027] Figure 2 This is a cross-sectional view of the copper block after it has been placed into the machining fixture.

[0028] Figure 3 This is a photograph of the finished copper block obtained after resin plugging.

[0029] Explanation of the reference numerals in the figure: 1- Fixture plate body; 11- Limiting groove; 2- Copper block; 21- Through hole; 3- Adhesive tape; 4- Vent hole. Detailed Implementation

[0030] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein.

[0031] The technical solutions in this application will now be described with reference to the accompanying drawings. Example 1

[0032] This embodiment provides a resin plugging method for large-diameter through holes on a copper block. The copper block has at least one through hole to be plugged, and the diameter of the through hole is ≥10mm. The method includes the following steps: S1: Apply tape to the copper block to seal one end of the through hole; S2: Place the copper block into the limiting groove on the fixture, with the side of the copper block with the tape facing the bottom of the limiting groove; S3: Drill a vent hole through the jig and tape along the central axis of the through hole; S4: Press resin ink into the through hole through the unsealed end until the resin ink completely fills the inside of the through hole; S5: Bake the filled copper block and the fixture together at high temperature to completely cure the resin ink in the through hole; The diameter of the vent hole is smaller than that of the through hole.

[0033] By attaching tape to one side of the copper block, the through hole with both ends is converted into a blind hole structure with one end closed and the other open. This prevents the resin ink from flowing out of the other end of the through hole due to its own weight and the pressure of plugging the hole during the pressing process. At the same time, placing the side of the copper block with tape facing the bottom of the limiting groove allows the bottom of the groove to provide rigid support for the sealing tape on the entire plane. When the resin ink is pressed in, it can completely offset the downward pressure of the resin on the tape under the large diameter, avoiding failure problems such as bulging, damage, delamination, and curling of the tape due to pressure, and ensuring the stability of the resin filling process. In this process, by drilling vent holes in the fixture and tape, the air squeezed by the resin in the blind hole can be continuously and smoothly discharged to the outside through the vent holes during the resin ink pressing process in step S4, without forming air bubbles or voids in the hole. At the same time, the diameter of the vent holes is much smaller than the diameter of the through hole to be plugged. The viscosity and surface tension of the resin ink itself can be used to achieve the effect of "venting only and not leaking glue", thus taking into account both the venting performance and the requirement of preventing glue leakage. This effectively eliminates internal voids and air bubbles, achieves complete and full filling, and significantly improves the resin plugging quality of large-diameter through holes.

[0034] The fixture features a locating groove that matches the dimensions of the copper block, providing rigid circumferential positioning of the copper block in the horizontal direction to ensure its stability during processing. Simultaneously, during resin filling, the locating groove prevents horizontal displacement of the copper block, avoiding resin ink from falling onto the copper surface in non-hole-filling areas. This eliminates the problem of resin residue on the copper surface at its source, eliminating the need for subsequent cleaning procedures.

[0035] In this embodiment, the pore diameter of the vent is 1-3 mm, preferably 2 mm.

[0036] It should be understood that the vent hole diameter ranges from 1-3mm, much smaller than the through-holes to be plugged on the copper block. Due to the high viscosity and surface tension of the resin ink, leakage cannot occur within this vent hole diameter, thus maintaining the sealing performance of the blind hole sealing structure. At the same time, this vent hole diameter is sufficiently unobstructed, allowing air inside the hole to be quickly and completely expelled during plugging, preventing air bubbles and voids caused by poor venting due to an excessively small vent diameter. Preferably, 2mm represents the optimal balance between venting efficiency and leak-proof adhesive, ensuring instantaneous air expulsion while completely preventing resin ink leakage, thus achieving stable and full filling of large-diameter through-holes.

[0037] In this embodiment, the tape is a high-temperature tape with good high-temperature resistance to withstand the high-temperature baking during curing. It can effectively maintain the seal integrity during the entire baking process, continuously and stably block the end face of the through hole, ensure that the blind hole structure does not fail, and provide a reliable foundation for the full filling of large-diameter resin. In addition, the high-temperature tape has strong high-temperature stability, leaves no adhesive residue after peeling, and will not contaminate the copper surface, thereby reducing subsequent cleaning processes and simplifying the manufacturing process.

[0038] Specifically, the tapes can be polyimide (PI) high-temperature tape, polyester (PET) high-temperature tape, polytetrafluoroethylene (PTFE) high-temperature tape, etc.

[0039] In this embodiment, step S5 further includes grinding the surface of the copper block after curing.

[0040] After the resin filler cures, it may be slightly higher than the surface of the through hole, or a small amount of overflow may form at the hole opening. Excess resin can be removed by grinding, so that the resin inside the hole is flush with the surface of the copper block, keeping the copper surface smooth and free of impurities. This avoids delamination and poor bonding when the copper block is laminated with the circuit board later, and improves the reliability of the lamination of the copper block with other materials.

[0041] It should be noted that the copper block is placed in the fixture for grinding. During grinding, only the side of the copper block located on the opening side of the limiting groove is ground. After grinding, the copper block is removed from the fixture, and then the tape is peeled off to obtain the finished product.

[0042] like Figure 3 As shown, Figure 3 The image shows the actual finished copper block. The copper block has a total of 3 through holes. As can be seen from the image, the through holes are full of resin without any voids, and there is no resin residue on the copper surface. Example 2

[0043] Please refer to Figure 1 and Figure 2 This embodiment provides a processing fixture, which is applied in the resin plugging method of Embodiment 1 (i.e., the fixture described in Embodiment 1). The processing fixture includes a fixture plate body 1 and a limiting groove 11 formed on the fixture plate body 1. As shown in the figure, the limiting groove 11 is provided on the top of the fixture plate body 1, and is used to place the copper block 2 to be plugged with resin.

[0044] In this embodiment, the depth of the limiting groove 11 is the same as the thickness of the copper block 2.

[0045] The depth of the limiting groove 11 is exactly the same as the thickness of the copper block 2, which allows the upper surface of the copper block 2 after being placed in the limiting groove 11 to be precisely flush with the upper surface of the fixture plate body 1, without any height difference. This provides a unified planar machining benchmark for drilling the vent hole 4, resin plugging, and surface grinding, improving the positional accuracy of the plugging and the consistency of the process.

[0046] It should be understood that the tape 3 at the bottom of copper block 2 is for easy observation. Figure 2 The copper block 2 is not fully inserted into the limiting groove 11. After the copper block 2 is actually inserted into the limiting groove 11, its upper surface is flush with the upper surface of the fixture plate body 1.

[0047] Preferably, in this embodiment, the thickness of the fixture plate body 1 is 1 mm greater than the thickness of the copper block 2.

[0048] In this embodiment, the planar contour dimensions of the limiting groove 11 are the same as those of the copper block 2.

[0049] The limiting groove 11 is perfectly matched with the plane contour of the copper block 2, which can form a circumferential all-round constraint on the copper block 2. During the entire process of drilling the vent hole 4, pressing in the resin ink, high-temperature baking, and surface grinding, the copper block 2 will not shift or shake. This avoids problems such as drilling eccentricity, plugging and overflowing glue, and grinding misalignment caused by the displacement of the copper block 2, and greatly improves the process positioning accuracy and product consistency.

[0050] In this embodiment, a positioning hole (not shown in the figure) is provided on the bottom surface of the fixture plate body 1. The positioning hole is correspondingly provided with the through hole 21 on the copper block 2, and the central axis of the positioning hole coincides with the central axis of the through hole 21.

[0051] The positioning hole serves as a positioning reference for drilling the vent hole 4 in step S3. Structurally, it ensures that the drilled vent hole 4 is precisely located at the center of the through hole 21 on the copper block 2, avoiding the problems of eccentricity or offset of the vent hole 4 caused by manual positioning or drilling without a reference. At the same time, using the preset positioning hole as a drilling guide eliminates the need for operators to perform additional measurement and calibration work, greatly simplifying the drilling alignment operation and improving convenience.

[0052] It should be understood that the limiting groove 11 and the positioning hole are pre-processed on the fixture plate body 1 by grooving and drilling, based on the size of the copper block 2 and the position of the through hole 21 on it.

[0053] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0054] Furthermore, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0055] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0056] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for resin plugging of large-diameter through holes in a copper block, wherein the copper block has at least one through hole to be plugged, characterized in that, The method includes the following steps: S1: Attach adhesive tape to the copper block to seal one end of the through hole; S2: Place the copper block into the limiting groove on the fixture, and make the side of the copper block with the tape face the bottom of the limiting groove; S3: Drill a vent hole through the fixture and the tape along the central axis of the through hole; S4: Press resin ink into the through hole through the unsealed end of the through hole until the resin ink completely fills the inside of the through hole; S5: The copper block that has been filled and the fixture are baked together at high temperature to completely cure the resin ink in the through hole; The diameter of the vent hole is smaller than the diameter of the through hole.

2. The resin plugging method for large-diameter through holes on a copper block according to claim 1, characterized in that, The diameter of the through hole is ≥10mm.

3. The resin plugging method for large-diameter through holes on a copper block according to claim 1, characterized in that, The diameter of the vent hole is 1-3mm.

4. The resin plugging method for large-diameter through holes on a copper block according to claim 1, characterized in that, The tape is a high-temperature resistant tape.

5. The resin plugging method for large-diameter through holes on a copper block according to claim 1, characterized in that, S5 also includes grinding the surface of the copper block after curing.

6. A machining fixture, characterized in that, The processing fixture is applied in the resin plugging method according to any one of claims 1 to 5. The processing fixture includes a fixture plate body and a limiting groove formed on the fixture plate body, the limiting groove being used to place a copper block.

7. The resin plugging method for large-diameter through holes on a copper block according to claim 6, characterized in that, The depth of the limiting groove is the same as the thickness of the copper block.

8. The resin plugging method for large-diameter through holes on a copper block according to claim 6, characterized in that, The thickness of the fixture plate body is 1 mm greater than the thickness of the copper block.

9. The resin plugging method for large-diameter through holes in a copper block according to claim 6, characterized in that, The planar contour dimensions of the limiting groove are the same as those of the copper block.

10. The resin plugging method for large-diameter through holes on a copper block according to claim 6, characterized in that, The fixture plate body has a positioning hole on the side away from the limiting groove. The positioning hole is corresponding to the through hole on the copper block, and the central axis of the positioning hole coincides with the central axis of the through hole.

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