A circuit board structure and method for improving the alignment accuracy of the press-bonded interlayer of a circuit board

Abstract

The application discloses a circuit board structure and method for improving the interlaminar alignment precision of a circuit board. The circuit board structure is improved based on the existing Pin-lam positioning hole, and a plurality of conductive blocks capable of pre-fusing prepreg after being powered on are arranged on the edges of the circuit board. According to the circuit board structure, the circuit board A and the circuit board B are manufactured, and when the interlaminar alignment of the circuit board is performed, the X-ray irradiation function is used to accurately identify and match the T-face target and the B-face target on the circuit board A and the circuit board B, so that high-precision automatic alignment is realized. Then, the electromagnetic hot melting function of the two vacuum tables is started, so that the conductive blocks designed on the circuit board A and the conductive blocks designed on the circuit board B are fused with the prepreg as fixed points, respectively, and the relative position between the layers is kept unchanged during the fusion process, so that preliminary positioning is realized, and the alignment precision is further improved. After the preliminary fusion positioning, the whole is subjected to Pin-lam pressing through the Pin-lam positioning hole, so that higher alignment precision between the layers during the pressing process is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit board processing, in particular to a circuit board structure and method for improving the interlayer alignment accuracy of circuit board pressing. BACKGROUND

[0002] In the manufacturing process of multi-layer circuit boards (MLB), especially for high-density multi-layer circuit boards with N+N structure, the alignment accuracy between the pressing layers is a key factor to ensure product performance and quality. With the rapid development of electronic technology, the integration of electronic products is becoming higher and higher, and the number of layers of circuit boards is increasing, and the requirement for interlayer alignment accuracy is becoming increasingly stringent. Currently, the widely used Pin-Lam (Pin Lamination) method is an effective pressing positioning technology, which realizes accurate alignment of multi-layer boards by setting PIN pinholes on the board edge. This method can meet the production requirements when the number of layers of the multi-layer board is relatively small and the alignment accuracy requirement is relatively loose, such as ≥3 mil. However, with the increase in the number of layers and the improvement in the alignment accuracy requirement, such as requiring an interlayer offset of ≤2 mil, or even 1 mil, the limitations of the Pin-Lam method gradually appear.

[0003] Chinese Patent No. CN111800959A discloses a fusion riveting method for improving the interlayer alignment accuracy of a circuit board. Before processing the positioning hole, the A-face target and the B-face target are identified at the same time, and the midpoint of the line connecting the A-face target and the B-face target is taken as the center of the positioning hole. The deviation of the positioning hole from the center of the A-face target or the center of the B-face target is less than 0.025 mm. The positioning hole can take into account the A and B face layer deviation, reduce the problem of single core plate A and B face misalignment, and improve the interlayer alignment accuracy of the multi-layer printed circuit board in one pressing, reduce the scrap rate of the circuit board caused by the positioning hole, and avoid causing great waste. However, for high-density multi-layer circuit boards with N+N structure and high precision, the above method still cannot meet the requirements.

[0004] Therefore, how to overcome the above-mentioned defects has become an important topic for technicians in the field to solve. SUMMARY

[0005] The present application overcomes the shortcomings of the above-mentioned technology and provides a method and structure for manufacturing an IC carrier plate.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] The first aspect discloses a circuit board structure for improving the alignment accuracy of a circuit board during pressing, comprising a circuit board, wherein a plurality of T-face targets 1 are designed on the top layer of the circuit board at the edge of the circuit board, a plurality of B-face targets 2 corresponding to the positions of the T-face targets 1 are designed on the bottom layer of the circuit board, a plurality of conductive blocks 3 capable of pre-fusing prepreg after being powered on are arranged on the edge of the circuit board, and a plurality of Pin-lam positioning holes 4 are arranged at the remaining positions of the edge of the circuit board.

[0008] Preferably, the conductive block 3 is a copper block, and the plurality of conductive blocks 3 are uniformly and spacedly arranged at the edge positions of the circuit board.

[0009] Preferably, the size of the conductive block 3 is 8*8 mm.

[0010] Preferably, the T-face targets 1 and the B-face targets 2 are arranged inside a square ring formed by the lines of the plurality of conductive blocks 3; the T-face target 1 is in the shape of a circular ring, and each T-face target 1 is provided with a B-face target 2 in the shape of a solid circle inside the circular ring, and the centers of the T-face target 1 and the B-face target 2 coincide.

[0011] Preferably, the T-face target 1 is a non-conductive circular ring, and the B-face target 2 is a circular copper PAD.

[0012] Preferably, the inner ring diameter of the T-face target 1 is 3 mil, and the diameter of the B-face target 2 is 1 mil.

[0013] Preferably, the plurality of T-face targets 1 at the same edge, the plurality of B-face targets 2 at the same edge, and the plurality of Pin-lam positioning holes 4 at the same edge are arranged in parallel.

[0014] Preferably, the circuit board is provided with one conductive block 3 at each of the four corner positions of the edge of the circuit board, and one or more conductive blocks 3 are uniformly arranged on the long edge of the circuit board; two T-face targets 1 are arranged at the corner positions on one side of the short edge of the circuit board, and two T-face targets 1 are symmetrically arranged on the other side of the short edge of the circuit board; and one Pin-lam positioning hole 4 is arranged at the midpoint of the line connecting the two T-face targets 1 at the same side of the short edge.

[0015] The second aspect provides a method for improving the alignment accuracy of a circuit board during pressing, comprising the following steps:

[0016] Step A: preparing a circuit board A with completed circuits and a circuit board B with completed circuits, wherein the circuit board A and the circuit board B adopt the circuit board structure of the first aspect;

[0017] Step B: placing the circuit board A with completed circuits on a vacuum table with X-ray function and electromagnetic heat melting function;

[0018] Step C, pre-laminate the prepreg on the circuit board A;

[0019] Step D, use another vacuum table with electromagnetic hot melting function to suck up the circuit board B which has been made, and through X-ray irradiation, automatically align the target with the circuit board A;

[0020] Step E, turn on the electromagnetic hot melting function of the two vacuum tables, and fuse the circuit board A, the prepreg, and the circuit board B to achieve preliminary positioning;

[0021] Step F, after fusion, perform Pin-lam pressing on the whole to obtain a multi-layer circuit board.

[0022] Compared with the prior art, the beneficial effects of the present application are:

[0023] 1. The circuit board structure of the present case is improved for the existing circuit board edge design that needs to be pressed. Based on the existing Pin-lam positioning hole, a plurality of conductive blocks that can heat the prepreg after being powered on are arranged on the edge of the board, so that the above circuit board structure can be used for circuit board pressing interlayer alignment, and the electromagnetic hot melting technology can be used for alignment. The equipment table adopts electromagnetic hot melting structure, which can perform electromagnetic fusion on the circuit board edge after pre-laminating the prepreg, which helps to maintain the stability and consistency of the layers during the pressing process. In addition, the design of the T-face target and the B-face target facilitates the subsequent application of the circuit board in the pressing process to monitor and correct the alignment of the layers so as to intuitively judge whether there is alignment deviation between the layers by comparing the relative positions of the T-face target and the B-face target, and adjust in time.

[0024] And still retain the setting of Pin-lam positioning hole, which is used to further provide accurate positioning reference in the pressing process, can ensure the accurate alignment between layers.

[0025] 2. The T-face target and B-face target of the present case are arranged inside the square ring formed by the connection of multiple conductive blocks, which can stagger the distribution of the target and the conductive block, reduce the influence between each other, ensure the demand for alignment accuracy, and avoid unnecessary space waste. The circular T-face target provides a clear boundary, facilitating identification and positioning during the pressing process. At the same time, the internal circular B-face target serves as a more accurate alignment point, further improving the accuracy of positioning. The design of the circle center overlapping ensures the accurate correspondence between the T-face target and the B-face target, making it easier to achieve accurate alignment between layers during multi-layer pressing. Moreover, the combination design of the circular ring and the circular target in the present case is more intuitive in vision, reducing the recognition errors and confusion caused by high similarity in shape, so that the automatic alignment system can more accurately identify and lock the target position, ensuring the accuracy of alignment, thereby improving the alignment accuracy between the subsequent circuit board pressing layers. The B-face target of the present case is designed as a solid circle, which serves as the core point of alignment. On the one hand, the solid area of the circular B-face target is relatively large, providing more identification information to facilitate clearer and more explicit identification during X-RAY identification, which is conducive to improving the stability during alignment and thus reducing alignment deviation.

[0026] 3. The circuit board structure of the present case is arranged in parallel by limiting multiple T-face targets, multiple B-face targets, and multiple Pin-lam positioning holes on the same side, which helps to achieve high-precision alignment during multi-layer pressing and manufacturing. Specifically, the conductive blocks arranged at the four corners of the edge of the circuit board can ensure accurate alignment of the circuit board through the four corners. By arranging targets symmetrically on both sides of the short edge of the circuit board, the symmetry during manufacturing can be ensured, which is conducive to precise control of interlayer alignment. In addition, since the length of the short edge is shorter, arranging targets on the short edge makes it easier to achieve high-precision alignment operation, thereby effectively controlling the alignment accuracy.

[0027] 3. The method according to the first aspect of the circuit board structure is used to manufacture the circuit board A and the circuit board B, so that the circuit board A and the circuit board B have the T-face target, the B-face target, the conductive block and the Pin-lam positioning hole, and when the circuit board is pressed and aligned, the X-ray irradiation function is used to accurately identify and match the T-face target and the B-face target on the circuit board A and the circuit board B. The T-face target and the B-face target provide a plurality of accurate reference points, and the targets can be clearly identified under X-ray irradiation, so that automatic alignment with high precision is realized. Then, the electromagnetic hot melting function of the two vacuum tables is turned on in step E, so that the conductive block designed on the circuit board A and the conductive block designed on the circuit board B are fused with the prepreg as fixed points, respectively, so that the relative position between the layers is ensured to remain unchanged during the fusion process, so as to realize preliminary positioning and improve the alignment accuracy. In addition, in addition to the target alignment and electromagnetic hot melting fusion, after the preliminary fusion positioning, the Pin-lam pressing is performed on the whole through the setting of step F, so as to ensure that the alignment accuracy between the layers is higher during the pressing process. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a schematic diagram of the board edge structure design of the circuit board structure of the embodiment one of the present application.

[0029] Figure 2 is an enlarged schematic diagram of the T-face target and the B-face target at a certain place of the circuit board structure of the embodiment one of the present application.

[0030] Figure 3 is a flowchart of the embodiment two of the present application.

[0031] Figure 4 is a schematic diagram of the N+N structure circuit board arrangement realized on the basis of the method of the embodiment two.

[0032] Wherein: 1-T-face target, 2-B-face target, 3-conductive block, 4-Pin-lam positioning hole, 100-circuit board A, 200-circuit board B, 300-first vacuum table, 400-prepreg, 500-second vacuum table. DETAILED DESCRIPTION

[0033] The features of the present application and other related features are further described in detail in the following embodiments, so as to facilitate the understanding of the skilled in the art:

[0034] Embodiment one

[0035] As Figure 1 and Figure 2As shown, a circuit board structure for improving the interlayer alignment accuracy of the circuit board pressing process includes a circuit board, the circuit board is designed with a plurality of T-face targets 1 on the top layer of the board edge and a plurality of B-face targets 2 on the bottom layer corresponding to the positions of the T-face targets 1, and a plurality of conductive blocks 3 capable of pre-fusing the prepreg after being heated by power supply are arranged on the board edge, and a plurality of Pin-lam positioning holes 4 are arranged at the remaining positions of the board edge.

[0036] As described above, the present application improves the design of the board edge of the circuit board that needs to be pressed, and based on the existing Pin-lam positioning hole 4, a plurality of conductive blocks 3 capable of pre-fusing the prepreg after being heated by power supply are arranged on the board edge, so that the above circuit board structure can be used for interlayer alignment of circuit board pressing, and the electromagnetic hot melting technology can be used for alignment. The equipment table adopts electromagnetic hot melting structure, which can perform electromagnetic fusion on the board edge of the circuit board after pre-laminating the prepreg, which helps to maintain the stability and consistency of the interlayer during the pressing process. In addition, the design of T-face targets and B-face targets can monitor and correct the alignment of the interlayer during the subsequent pressing process, so that the relative positions of the T-face targets and the B-face targets can be compared to directly judge whether there is alignment deviation between the layers, and timely adjustment can be made.

[0037] And the Pin-lam positioning hole 4 is still retained, which can provide accurate positioning reference during the pressing process, and can ensure the accurate alignment between the layers.

[0038] As a preferred embodiment, the conductive block 3 is a copper block, and a plurality of conductive blocks 3 are uniformly spaced along the most edge position of the circuit board edge. In this way, the conductive block is a copper block, which is an excellent heat-conducting material and can quickly and uniformly transfer heat, ensuring uniform conduction along the circuit board edge and uniform heat distribution, which helps to achieve uniform softening and fusion of the prepreg, thereby improving the bonding quality and consistency of the interlayer. Moreover, the conductive blocks are uniformly spaced at the most edge position of the board edge, which helps to disperse the stress generated during the pressing process, so as to reduce the deformation or damage of the interlayer caused by stress concentration, thereby improving the overall stability and reliability of the circuit board.

[0039] As a preferred embodiment, the size of the conductive block 3 is 8*8mm. In this way, by designing the size of the conductive block 3 as 8*8mm, accurate conductive heating area can be generated at the edge of the circuit board based on smaller size design, on the one hand to achieve local and accurate fusion control during the pressing process, avoiding unnecessary thermal stress on the entire circuit board; on the other hand, the conductive block can be placed more accurately in the area that needs to be pre-fused, thereby improving the interlayer alignment accuracy. Moreover, accurately controlling the size of the conductive block 3 helps to reduce production costs.

[0040] like Figure 1 As shown, in a specific implementation, the T-side target 1 and the B-side target 2 are set inside the square ring formed by the connection of multiple conductive blocks 3; the T-side target 1 is in the shape of a ring, and each T-side target 1 has a corresponding solid circle B-side target 2 located inside its ring, and the centers of the T-side target 1 and the B-side target 2 coincide.

[0041] As described above, the T-side target 1 and B-side target 2 are positioned inside the square ring formed by the connecting lines of multiple conductive blocks 3. This allows the targets and conductive blocks to be staggered, reducing mutual interference, ensuring the required alignment accuracy, and avoiding unnecessary space waste. The circular T-side target 1 provides a clear boundary, facilitating identification and positioning during the lamination process. Simultaneously, the inner circular B-side target 2 serves as a more precise alignment point, further improving positioning accuracy. The coincident design ensures a precise correspondence between the T-side target 1 and the B-side target 2, making it easier to achieve precise alignment between layers during multi-layer lamination. Specifically, in existing technologies, both targets are designed as rings, with a larger ring nested within a smaller one. The boundary between the two rings can cause visual confusion during automatic identification and alignment, leading to identification errors and affecting the alignment accuracy between the laminated layers of the circuit board. In contrast, the combined ring and circular target design in this invention is more visually intuitive, reducing identification errors and confusion caused by high shape similarity. This allows the automatic alignment system to more accurately identify and lock the target position, ensuring alignment accuracy and improving the alignment accuracy between subsequent laminated layers of the circuit board. In this design, the B-side target 2 is designed as a solid circle, serving as the core of the alignment. The relatively large solid area of ​​the circular B-side target 2 provides more identification information, making it clearer and more precise during X-ray identification, thus improving the stability of the alignment process and reducing alignment deviation.

[0042] As an optional implementation, the T-side target 1 is a non-conductive ring, and the B-side target 2 is a circular copper PAD. Thus, the non-conductive ring, serving as the T-side target 1, with its clear boundaries and defined shape, facilitates high-precision positioning during multilayer lamination. Furthermore, because it is non-conductive, it does not interfere with the normal operation of the circuit, ensuring positioning accuracy. The design of the B-side target 2 as a circular copper PAD gives it high reflectivity and significant contrast with the surrounding non-conductive material, making it easier for the identification system to capture and recognize the copper PAD, thereby improving the accuracy and stability of the identification process.

[0043] As an optional embodiment, the inner ring diameter of the T-face target 1 is 3 mil, and the diameter of the B-face target 2 is 1 mil. In this way, a 1 mil gap is left between the inner ring of the T-face target 1 and the circular outer edge of the B-face target 2, which can accommodate the deviation that may occur during actual manufacturing of the T-face and B-face; and the smaller diameter of the B-face target 2 makes it easier to achieve high-precision alignment during alignment, which can meet the requirement of an interlayer deviation of ≤2 mil, ensuring the precision and accuracy of target recognition.

[0044] As shown in Figure 1 , the multiple T-face targets 1 on the same side, the multiple B-face targets 2 on the same side, and the multiple Pin-lam positioning holes 4 on the same side are arranged in parallel. In this way, by requiring the T-face target, the B-face target, and the Pin-lam positioning hole to be arranged in parallel on the same side edge, this layout helps to maintain the stability and consistency between the layers during pressing, avoiding misalignment and deviation.

[0045] As an optional embodiment, the circuit board is provided with one conductive block 3 at each of the four corner positions of the edge of the board, and one or more conductive blocks 3 are uniformly arranged on the long edge of the board. Two T-face targets 1 are arranged on the corner position of one side of the short edge of the board, and two T-face targets 1 are symmetrically arranged on the other side of the short edge of the board. A Pin-lam positioning hole 4 is arranged at the midpoint of the line connecting the two T-face targets 1 on the same side of the short edge.

[0046] As described above, by limiting the parallel arrangement of the multiple T-face targets 1, the multiple B-face targets 2, and the multiple Pin-lam positioning holes 4 on the same side, high-precision alignment can be achieved during multi-layer pressing and manufacturing. Specifically, the conductive blocks 3 arranged at the four corners of the edge of the board can ensure accurate alignment of the circuit board through the four corners. By symmetrically arranging the targets on the two short edges of the board, the symmetry during manufacturing can be ensured, which is beneficial to precise control of interlayer alignment. In addition, since the length of the short edge is shorter, it is easier to achieve high-precision alignment operation by arranging the targets on the short edge, thereby effectively controlling the alignment precision.

[0047] Example Two

[0048] As shown in Figure 3 and Figure 4 , a method for improving the interlayer alignment precision of a circuit board pressing process, comprising the following steps:

[0049] Step A, preparing a circuit board A with completed circuit and a circuit board B with completed circuit, wherein the circuit board A and the circuit board B adopt the circuit board structure described in Example One;

[0050] Step B, first place the circuit board A with completed circuit on the vacuum table with X-ray function and electromagnetic heat melting function, which is recorded as the first vacuum table 300;

[0051] Step C, pre-laminate the prepreg 400 on the circuit board A;

[0052] Step D, use another vacuum table with electromagnetic heat melting function to suck up the circuit board B with completed circuit, and through X-ray irradiation, automatically align the target with the circuit board A; another vacuum table with electromagnetic heat melting function is recorded as the second vacuum table 500;

[0053] Step E, turn on the electromagnetic heat melting function of the two vacuum tables to fuse the circuit board A, the prepreg and the circuit board B to achieve preliminary positioning;

[0054] Step F, turn off the electromagnetic heat melting function, that is, after fusion, the whole is subjected to Pin-lam pressing to obtain a multi-layer circuit board.

[0055] In specific implementation, the electromagnetic heat melting function refers to using electromagnetic induction principle to convert electrical energy into heat energy to melt the metal material in the workpiece, thereby achieving the purpose of fusion.

[0056] As described above, according to the circuit board structure of embodiment one, the circuit board A and the circuit board B are manufactured, so that the circuit board A and the circuit board B have T face target 1, B face target 2, conductive block 3 and Pin-lam positioning hole 4, which can be used for X-ray irradiation function to accurately identify and match the T face target 1 and the B face target 2 on the circuit board A and the circuit board B when the circuit board pressing interlayer alignment is performed. The setting of the T face target 1 and the B face target 2 provides multiple accurate reference points, and these targets can be clearly identified under X-ray irradiation, thereby realizing high-precision automatic alignment. Then through step E, the electromagnetic heat melting function of the two vacuum tables is turned on to use the electromagnetic induction principle to make the conductive block 3 designed on the circuit board A and the conductive block 3 designed on the circuit board B generate heat, so that the local material of the prepreg softens or melts, thereby realizing the preliminary positioning between the layers, so as to be able to accurately control the heating area, to realize the accurate alignment between the layers without damaging the surrounding materials, to provide a good foundation for subsequent Pin-lam pressing, to reduce the risk of misalignment in the pressing process, thereby improving the alignment accuracy. In addition, in addition to target alignment and electromagnetic heat fusion, after preliminary fusion positioning, through the setting of step F, the whole is subjected to Pin-lam pressing by using the Pin-lam positioning hole 4, to ensure that the alignment accuracy between the layers is higher in the pressing process.

[0057] In summary, the present application proposes a new circuit board structure and a new method for improving the alignment accuracy between the pressing layers of the circuit board. By designing T-face targets on the top layer and B-face targets on the bottom layer on the edge of the circuit board, and using electromagnetic heat melting technology to make the conductive blocks pre-fuse the prepreg, and designing Pin-lam positioning holes, high-precision alignment of multi-layer circuit boards during pressing is achieved. This structure and method combines the traditional Pin-lam method and accurate recognition of the targets, effectively improving the alignment accuracy between the layers.

[0058] As described above, the present application protects a circuit board structure and method for improving the alignment accuracy between the pressing layers of the circuit board. All technical solutions that are the same or similar to the present application should be shown to fall within the scope of protection of the present application.

Claims

1. A circuit board structure for improving the alignment accuracy between lamination layers of a circuit board, comprising a circuit board, characterized in that, The circuit board has multiple T-face targets (1) on its top layer and multiple B-face targets (2) corresponding to the positions of the T-face targets (1) on its bottom layer. Multiple conductive blocks (3) capable of generating heat and pre-fusion of semi-cured sheets after being powered on are also provided on its edge. Multiple pin-lam positioning holes (4) are provided at other positions on the edge of the board. The T-face targets (1) and B-face targets (2) are located inside the square ring formed by the lines connecting the multiple conductive blocks (3). Each T-face target (1) is ring-shaped, and each T-face target (1) contains a solid circular B-face target (2) located within its ring. The centers of the T-side target (1) and the B-side target (2) coincide; the T-side target (1) is a non-conductive ring, and the B-side target (2) is a circular copper PAD; the circuit board has a conductive block (3) at each of the four corners of its outermost edge, and one or more conductive blocks (3) are evenly arranged on the long side of the circuit board; the circuit board has two T-side targets (1) near the corner of one short side of its side, and two T-side targets (1) are symmetrically arranged on the other short side of its side; a Pin-lam positioning hole (4) is provided at the midpoint of the line connecting the two T-side targets (1) on the same short side.

2. The circuit board structure according to claim 1, characterized in that, The conductive block (3) is a copper block, and multiple conductive blocks (3) are evenly spaced along the outermost edge of the circuit board.

3. The circuit board structure according to claim 2, characterized in that, The conductive block (3) has a size of 8*8mm.

4. The circuit board structure according to claim 1, characterized in that, The inner ring diameter of the T-side target (1) is 3 mil, and the diameter of the B-side target (2) is 1 mil.

5. The circuit board structure according to claim 1, characterized in that, Multiple T-face targets (1), multiple B-face targets (2), and multiple Pin-lam positioning holes (4) on the same side are all arranged in parallel.

6. A method for improving the alignment accuracy between lamination layers of a circuit board, characterized in that, Includes the following steps: Step A: Prepare circuit board A and circuit board B with the circuit already fabricated, wherein circuit board A and circuit board B adopt the circuit board structure described in any one of claims 1-5. Step B: First, place the circuit board A, which has already been fabricated, on a vacuum stage with X-ray and electromagnetic melting functions; Step C: Pre-stack the prepreg onto circuit board A; Step D: Use another vacuum stage with electromagnetic thermal melting function to pick up the circuit board B with the completed circuit, and irradiate it with X-ray to automatically align it with the circuit board A according to the target; Step E: Activate the electromagnetic thermal fusion function of the two vacuum stages to fuse circuit board A, prepreg, and circuit board B to achieve initial positioning; Step F: After fusion, the entire assembly is subjected to Pin-lam lamination to obtain a multilayer circuit board.

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