A multilayer HDI circuit board and a manufacturing method thereof

Abstract

The application discloses a multilayer HDI circuit board and a manufacturing method thereof. The method comprises the following steps: laminating a plurality of pattern-transferred circuit boards to form a semi-finished product; the semi-finished product comprises a circuit area and a positioning area; a plurality of positioning target rings are arranged in the positioning area; the center of the positioning target ring is arranged on a line connecting the center of the semi-finished product and the center of the vertex of the semi-finished product; a plurality of grooves are formed on the semi-finished product; the projection of the groove in the direction perpendicular to the semi-finished product is a square; alignment targets are arranged in the plurality of grooves; the circuit board is laminated with the semi-finished product through the alignment targets to obtain a laminated board; an exposure machine is aligned with the laminated board through the alignment targets to obtain a multilayer HDI circuit board; the method can improve product quality and reduce design cost. The application can be widely applied in the field of PCB manufacturing technology.

Description

Technical Field

[0001] This application relates to the field of PCB manufacturing technology, and in particular to a multilayer HDI circuit board and its manufacturing method. Background Technology

[0002] With the continuous development of the PCB manufacturing industry, the miniaturization and high-speed operation of electronic products have placed increasingly higher demands on circuit boards. Products are constantly shrinking in size and improving in performance. High-density integration (HDI) technology enables more miniaturized end-product designs while meeting higher standards of electronic performance and efficiency. In particular, arbitrary-layer HDI boards are generally manufactured using a build-up process. The more layers, the higher the technical level of the board, meeting the PCB industry's growing trend towards thinner, lighter, more integrated, and more precise designs.

[0003] In existing technologies, four CCD target holes are typically created using X-ray drilling after lamination for alignment within the inner layer. These four CCD target holes provide common target positioning for laser engraving, drilling, and circuit fabrication. However, during production, the target holes are easily damaged due to board expansion and contraction, as well as human error. Furthermore, during circuit alignment exposure, the PE value of the exposure machine must be set within ±50µm, leading to abnormal HDI blind via stack-up misalignment. Therefore, a new method for manufacturing multilayer HDI circuit boards is urgently needed. Summary of the Invention

[0004] The purpose of this application is to at least partially solve one of the technical problems existing in the prior art.

[0005] Therefore, one objective of this application is to provide a multilayer HDI circuit board and a method for manufacturing the same, which can improve product quality and reduce design costs.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted in this application includes: pressing several layers of circuit boards with transferred patterns together to form a semi-finished board; the semi-finished board includes a circuit area and a positioning area; several positioning target rings are set in the positioning area; the center of the positioning target ring is located on the line connecting the center of the semi-finished board and the center of the vertex of the semi-finished board; several grooves are formed on the semi-finished board; the grooves are located in the positioning area; the projection of the groove in the direction perpendicular to the semi-finished board is a square, and one edge of the square is tangent to the positioning target ring; alignment targets are set in the several grooves; the circuit board layer is aligned and pressed with the semi-finished board through the alignment targets to obtain a pressed board; the exposure machine is aligned and exposed with the pressed board through the alignment targets to obtain a multilayer HDI circuit board.

[0007] In addition, the method for manufacturing a multilayer HDI circuit board according to the above embodiments of the present invention may also have the following additional technical features:

[0008] Furthermore, in this embodiment of the application, the alignment target includes: an inner copper ring and a copper-free target hole disposed in the middle of the inner copper ring.

[0009] Furthermore, in this embodiment of the application, the diameter of the inner copper ring is a, where a satisfies 2.8mm≤a≤3.2mm.

[0010] Furthermore, in this embodiment of the application, the diameter of the copper-free circular target hole is b, where b satisfies 0.45mm≤b≤0.55mm.

[0011] Furthermore, in this embodiment of the application, the number of positioning target rings includes four.

[0012] Furthermore, in this embodiment of the application, the diameter of the positioning target ring is c, where c satisfies 3.170mm≤c≤3.180mm.

[0013] Furthermore, in this embodiment of the application, the projection of the groove perpendicular to the direction of the semi-finished plate is a square, and the side length l of the square satisfies: 4.9mm≤l≤5.1mm.

[0014] Furthermore, in this embodiment of the application, the thickness of the copper-free circular target hole is the same as the thickness between two adjacent circuit layers in the plurality of circuit layers.

[0015] Furthermore, in this embodiment of the application, the positioning target ring includes a foolproof mark.

[0016] In addition, this application also provides a multilayer HDI circuit board, which is manufactured by a multilayer HDI circuit board manufacturing method described in any of the above embodiments.

[0017] The advantages and beneficial effects of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application:

[0018] This application can set a groove in the positioning area of ​​the multilayer semi-finished board and set an alignment target in the groove. The positioning between the multilayer semi-finished board and the exposure machine is completed by the target. The groove protects the alignment target, which can avoid damage to the alignment target and abnormal defects caused by HDI blind hole stacking. This method can improve product quality and reduce design costs. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the steps of a multilayer HDI circuit board fabrication method in a specific embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram showing the position and structure of the positioning target ring in a specific embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the groove and alignment target structure in a specific embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of a copper-free circular target hole in a specific embodiment of the present invention. Detailed Implementation

[0023] The following detailed description, in conjunction with the accompanying drawings, illustrates the principles and processes of the multilayer HDI circuit board fabrication method, system, apparatus, and storage medium according to embodiments of the present invention.

[0024] Currently, the following two methods are generally used for the exposure and alignment of layer stack-up patterns in PCB HDI boards with arbitrary layers during production:

[0025] 1) Four 3.175mm CCD target holes are punched out inside the inner layer by X-ray after lamination for alignment. The four CCD target holes provide common target positioning for laser, drilling and circuit fabrication. During the production process, the target holes are easily damaged due to board expansion and contraction and human error. When the circuit is aligned and exposed, the alignment PE value of the exposure machine needs to be set within ±50um, which will lead to abnormal HDI blind via stack-up.

[0026] 2) Pre-positioning is achieved using CCD positioning holes at the four board corners. The laser first burns out the inner square concave targets at the four corners, then grasps the center point of the square concave targets, and the laser machine automatically stretches the drilling tape to perform laser drilling. Simultaneously, the laser burns out the annular convex target on the board surface. During LDI exposure for circuit pattern transfer, the LDI machine grasps the convex target and automatically aligns it for exposure. The main disadvantages of this method are: when the laser burns out the annular convex target on the board surface, irregular laser-burned edges are prone to occur, making alignment difficult. Manual three-point positioning of the annular convex target on the computer is required, which easily leads to alignment misalignment. Furthermore, the interlayer dielectric thickness of any layer HDI board is generally thin, around 50µm. After each electroplating filling of the annular convex target grooves, due to the shallow groove depth, the copper color at the bottom of the grooves easily reflects light, making it impossible for the LDI machine to identify the position of the annular convex target during exposure. This results in high exposure difficulty, misalignment, low production efficiency, and many other unstable factors.

[0027] In view of the shortcomings of the prior art, referring to Figure 1 This invention provides a method for manufacturing a multilayer HDI circuit board, which may include the following steps:

[0028] S1. Press together several layers of circuit boards that have been patterned and transferred to form a semi-finished board; the semi-finished board includes a circuit area and a positioning area;

[0029] In this step, the patterned multilayer substrate can be physically laminated to form a multilayer board according to existing technology; there are no restrictions on the specific lamination method or the tools used for lamination.

[0030] S2. A plurality of positioning target rings are set in the positioning area; the center of the positioning target ring is set on the line connecting the center of the semi-finished plate and the center of the vertex of the semi-finished plate;

[0031] In this step, after the pressing is completed, several positioning target rings are drilled out of the board using an X-Ray machine with a center-to-target drill. The positioning target rings can be set in the positioning area, and the center of the positioning target rings can be set on the line connecting the center of the semi-finished board and the center of the vertex of the semi-finished board.

[0032] S3. A plurality of grooves are formed on the semi-finished product plate; the grooves are disposed in the positioning area; the projection of the grooves in the direction perpendicular to the semi-finished product plate is a square, and one edge of the square is tangent to the positioning target ring;

[0033] In this step, several grooves can be formed on the positioning area of ​​the semi-finished plate. The projection of the grooves in the direction perpendicular to the semi-finished plate is a square, and one edge of the square is tangent to the positioning target ring.

[0034] S4. Alignment targets are set in the plurality of grooves;

[0035] In this step, after pre-positioning with the four corner positioning target rings of the semi-finished board, the laser first burns out the inner copper ring in the square grooves at the four corners of the board, and at the same time burns out the copper-free round target point in the middle of the inner copper ring. During laser drilling, the copper-free round target point is grabbed and the laser drill strip is automatically stretched to perform laser drilling, so that the positional accuracy of the laser blind hole is consistent with the coordinate coefficient of the round target point.

[0036] S5. Using the alignment target, the circuit board layer is aligned and pressed with the semi-finished board to obtain a pressed board;

[0037] In this step, the circuit board layer can be aligned and pressed with the semi-finished board using an alignment target to obtain a laminated multilayer circuit board.

[0038] S6. Using the alignment target, the exposure machine and the laminating plate are aligned and exposed to obtain a multilayer HDI circuit board.

[0039] In this step, after the multilayer circuit board is laminated, the laminated circuit board needs to undergo an exposure process. During exposure, the exposure machine and the lamination plate can be aligned using an alignment target, and then the circuit exposure of the laminated circuit board is completed, forming the final circuit layer of the multilayer HDI circuit board.

[0040] Furthermore, in some embodiments of this application, the alignment target may include: an inner copper ring and a copper-free target hole. The inner copper ring may be disposed in the middle of the inner copper ring, and the centers of the inner copper ring and the copper-free target hole coincide in the direction perpendicular to the semi-finished plate.

[0041] Furthermore, in some embodiments of this application, the diameter of the inner copper ring can be set to a, where a can satisfy 2.8mm≤a≤3.2mm.

[0042] Furthermore, in some embodiments of this application, the diameter of the copper-free circular target hole can be set to b, where b can satisfy 0.45mm≤b≤0.55mm.

[0043] Furthermore, in some embodiments of this application, the number of positioning target rings may include four.

[0044] Furthermore, in some embodiments of this application, the diameter of the positioning target ring can be set to c, where c can satisfy 3.170mm≤c≤3.180mm.

[0045] Furthermore, in some embodiments of this application, the projection of the groove in the direction perpendicular to the semi-finished plate can be a square, and the side length l of the square can satisfy: 4.9mm≤l≤5.1mm.

[0046] Furthermore, in some embodiments of this application, the thickness of the copper-free circular via is the same as the thickness between two adjacent circuit layers in a multi-layer circuit board. The copper-free circular via has a certain depth, the value of which is the same as the thickness between two adjacent circuit layers in a multi-layer circuit board.

[0047] Furthermore, in some embodiments of this application, the positioning target ring may include a foolproof mark.

[0048] The following is combined with Figures 2-4 The method for fabricating a multilayer HDI circuit board according to this application is described below:

[0049] In this embodiment, the inner copper ring has a diameter of 3mm, the diameter of the copper-free target hole is 0.5mm, the number of positioning target rings includes 4, the diameter of the positioning target ring is 3.175mm, the projection of the groove perpendicular to the direction of the semi-finished board is a square, the side length l of the square is 5mm, and the thickness of the copper-free target hole is the same as the thickness between two adjacent circuit layers in the plurality of circuit boards, which is 1.6mm.

[0050] First, step one, refer to Figure 1 According to existing technology, the multilayer substrate with transferred patterns is laminated to form a multilayer board. After lamination, four (ABCD) 3.175mm horizontal through-hole targets with anti-foolproof spacing are drilled at the four corners of the board using the center-target drilling method of X-Ray machine.

[0051] Secondly, in step two, refer to Figures 2-4 After pre-positioning using the CCD positioning target holes (ABCD) at the four corners of the board in step one, the laser first burns out square grooves at the four corners of the board. The projection size of the grooves in the direction perpendicular to the multilayer board is 5mm*5mm. Then, an inner copper ring with a diameter of 3.0mm is set in the groove. At the same time, a copper-free target hole with a diameter of 0.5mm is burned out in the middle of the inner copper ring. The laser can directly burn to the bottom layer of the inner copper ring. At this time, the depth of the copper-free target hole is the same as the thickness between any two adjacent layers of circuits in several layers of circuit board, which is 1.6mm. During laser drilling, a 0.5mm target point is grabbed, and the laser drill tape is automatically stretched to perform laser drilling, so that the positional accuracy of the laser blind hole is consistent with the coordinate coefficient of the 0.5mm target point.

[0052] Next, in step three, multilayer boards can be added using copper-free circular target holes. During the addition of layers, the copper-free circular target holes can be aligned using a laminating machine. After positioning, lamination can be performed. After lamination, the circuitry on the added circuit board needs to be fabricated, requiring pattern transfer. During pattern transfer, the LDI machine can grab a 0.5mm circular target point and automatically stretch the coefficient for alignment and exposure, ensuring that the pattern transfer coefficient matches the coefficient of the laser blind via in the actual PCB board. At the same time, alignment targets for the next addition of layers can be fabricated at specified positions on the corners of the added circuit board.

[0053] In summary, the multilayer HDI circuit board fabrication method of this application has the following advantages:

[0054] Compared to existing technologies, it is simpler and easier to implement, and can completely eliminate the unstable factors caused by the alignment of the existing technology with four CCD target holes and laser ring target (convex target). During the process of adding layers to HDI boards, laser drilling and circuit layering are carried out under the same expansion and contraction of the PCB board, which can effectively improve the alignment accuracy of blind via stacking of arbitrary interconnect HDI boards.

[0055] In addition, with Figure 1 Corresponding to the method described above, the embodiments of this application also provide a multilayer HDI circuit board, which can be manufactured by any of the multilayer HDI circuit board manufacturing methods described in the above embodiments.

[0056] It should be noted that the content of the above method embodiments is applicable to the multilayer HDI circuit board embodiments. The specific functions implemented by the multilayer HDI circuit board embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0057] In the foregoing description of this specification, the references to terms such as "one embodiment," "another embodiment," or "some embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

[0059] The above is a detailed description of the preferred embodiments of this application, but this application is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for fabricating a multilayer HDI circuit board, characterized in that, Includes the following steps: Several layers of circuit boards with transferred patterns are pressed together to form a semi-finished board; the semi-finished board includes a circuit area and a positioning area; Several through-hole positioning target rings with horizontal and spacing anti-foolproof structures are set in the positioning area by center-to-target drilling with an X-ray machine; the center of the positioning target ring is set on the line connecting the center of the semi-finished plate and the center of the vertex of the semi-finished plate. A plurality of grooves are formed on the semi-finished plate; the grooves are disposed in the positioning area; the projection of the grooves in the direction perpendicular to the semi-finished plate is a square, and one edge of the square is tangent to the positioning target ring; Alignment targets are set in the plurality of grooves. The alignment targets include: an inner copper ring and a copper-free target hole disposed in the middle of the inner copper ring. The thickness of the copper-free target hole is the same as the thickness between two adjacent circuit layers in the plurality of circuit boards. The inner copper ring has a diameter of 3 mm, the copper-free target hole has a diameter of 0.5 mm, the positioning target ring has a diameter of 3.175 mm, the square groove has a side length of 5 mm, and the copper-free target hole has a thickness of 1.6 mm, which is the thickness of the dielectric of the adjacent circuit layer. A laser picks up the copper-free circular target point in the alignment target, and an automatic stretching drill strip is used to perform laser drilling, so that the positional accuracy of the laser blind hole is consistent with the coordinate coefficient of the copper-free circular target point; through the alignment target, the circuit board layer is aligned and pressed with the semi-finished board to obtain a pressed board. The exposure machine picks up the copper-free circular target point in the alignment target and automatically stretches the coefficient for alignment exposure; through the alignment target, the exposure machine and the laminating plate are aligned and exposed to obtain a multilayer HDI circuit board.

2. The method for manufacturing a multilayer HDI circuit board according to claim 1, characterized in that, The number of positioning target rings includes four.

3. The method for manufacturing a multilayer HDI circuit board according to claim 1, characterized in that, The positioning target ring includes a foolproof marking.

4. A multilayer HDI circuit board, characterized in that, It is manufactured by the method of manufacturing a multilayer HDI circuit board according to any one of claims 1-3.

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