HDI circuit board

Abstract

The HDI circuit board comprises a copper-clad core plate and a plurality of layers of laminated copper foils which are sequentially connected to at least one surface side of the copper-clad core plate through bonding sheets, wherein an interlayer alignment structure is arranged between the copper-clad core plate and the plurality of layers of laminated copper foils, and the interlayer alignment structure comprises a reference copper disc arranged in the copper foil of the copper-clad core plate; the alignment copper rings are arranged at the positions, corresponding to the reference copper disc, in all the layers of laminated copper foil, the inner diameter of the alignment copper rings in all the layers of laminated copper foil is larger than the outer diameter of the reference copper disc, and the sizes of the alignment copper rings of all the layers of laminated copper foil from inside to outside are gradually increased; the HDI circuit board is provided with an observation hole used for exposing the reference copper disc and the alignment copper ring in the inner layer press fit copper foil. According to the interlayer alignment structure of the HDI circuit board, whether interlayer deviation exists in the laminated copper foil can be visually observed layer by layer, and the production cost of the HDI circuit board can be reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of circuit board, more specifically, it relates to a kind of interlayer alignment structure of HDI (High Density Interconnector). BACKGROUND

[0002] When making HDI circuit board, copper foil needs to be hot-pressed on copper-clad core board layer by layer and conductive circuit is made, and the alignment degree between layers of each layer of conductive circuit needs to be strictly controlled.The existing interlayer alignment structure is to set concentric circle structure on multi-layer copper foil, and the relative position of each layer of concentric circle is detected by X-ray, and then it is judged whether the alignment degree between layers meets the requirements.However, this kind of interlayer alignment structure needs to use high-cost X-ray inspection equipment, and visual inspection cannot be carried out.In addition, this structure checks multi-layer copper foil synchronously, and if the alignment degree between layers of product does not meet the requirements, it can only be scrapped as a whole, causing excessive waste of materials. SUMMARY

[0003] In view of the deficiencies of the prior art, the main purpose of the utility model is to provide a kind of HDI circuit board that can be detected layer by layer whether interlayer is offset.

[0004] In order to achieve the above-mentioned main purpose, the utility model discloses a kind of HDI circuit board, including copper-clad core board and the multi-layer press copper foil connected in order on at least one surface side of the copper-clad core board by bonding sheet;Interlayer alignment structure is provided between the copper-clad core board and the multi-layer press copper foil, and the interlayer alignment structure includes:

[0005] Reference copper disc, set in the copper foil of the copper-clad core board itself;

[0006] Alignment copper ring, set in the position corresponding to the reference copper disc in each layer of the press copper foil;Wherein, the inner diameter of alignment copper ring in each layer of the press copper foil is greater than the outer diameter of the reference copper disc, and the size of alignment copper ring in each layer of the press copper foil gradually increases from inside to outside;

[0007] Among them, the HDI circuit board is provided with observation hole for exposing the reference copper disc and alignment copper ring in inner layer press copper foil.

[0008] Further, positioning target point is provided in each layer of the press copper foil, and the positioning target point is used as the position reference of conductive circuit and alignment copper ring in each layer of the press copper foil.

[0009] Further, from the thickness direction of the HDI circuit board, the reference copper disc and the alignment copper ring from inside to outside are sequentially and spaced apart.

[0010] Further, the reference copper disc has a solid circular structure.

[0011] Further, the radial width of the alignment copper ring is 0.2mm-0.5mm.

[0012] According to one embodiment of the present application, the interlayer alignment structure is arranged at four corners of the HDI circuit board.

[0013] According to another embodiment of the present application, the interlayer alignment structure is arranged at at least two opposite sides of the HDI circuit board.

[0014] Further, the interlayer alignment structure is also arranged at the middle part of the HDI circuit board.

[0015] Further, both opposite surface sides of the copper-clad core board are provided with multi-layered press-bonded copper foils, and the interlayer alignment structure is arranged between the copper-clad core board and the multi-layered press-bonded copper foils on the two opposite surface sides.

[0016] The technical scheme of the present application has the following advantages:

[0017] In the HDI circuit board of the present application, the copper foil of the copper-clad core board is provided with a reference copper disc, the position corresponding to the reference copper disc in each layer of press-bonded copper foil is provided with an alignment copper ring, and the HDI circuit board is provided with an observation hole for exposing the reference copper disc and the alignment copper ring, so that the relative position between the reference copper disc and each alignment copper ring can be visually observed from the observation hole, and then it can be determined whether the product is interlayerly deviated. Further, the interlayer alignment structure in the HDI circuit board of the present application can realize layer-by-layer inspection, that is, after the production process of each layer of press-bonded copper foil is completed, one layer deviation inspection can be performed, and if there is interlayer deviation, the subsequent production process can be terminated, thereby reducing the waste of materials.

[0018] In order to more clearly illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described in detail below with reference to the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a layout schematic diagram of the interlayer alignment structure of the HDI circuit board in the embodiment of the present application;

[0020] Figure 2 is a cross-sectional structure schematic diagram of the interlayer alignment structure in the embodiment of the present application;

[0021] Figure 3 is a front structure schematic diagram of the interlayer alignment structure in the embodiment of the present application. DETAILED DESCRIPTION

[0022] In the following description, many specific details are set forth in connection with specific embodiments in order to provide a thorough understanding of the present application. However, persons skilled in the art will understand that these embodiments and the following detailed description are merely exemplary and instructive and are not restrictive of the present application.

[0023] The HDI circuit board of the present application comprises a copper-clad core board and a plurality of laminated copper foils connected to at least one surface side of the copper-clad core board in sequence through adhesive sheets. Figure 1 and 2 As shown in Figs. 1 and 2, the HDI circuit board 100 described as an embodiment is a six-layer HDI circuit board, which comprises a copper-clad core board C having L3 and L4 copper foils / conductive circuits itself, one surface side of the copper-clad core board C is connected in sequence with L2 and L1 laminated copper foils, and the opposite surface side is connected in sequence with L5 and L6 laminated copper foils. Specifically, the L2 laminated copper foil is hot-pressed on the L3 laminated copper foil through an adhesive sheet P21, and the L1 laminated copper foil is hot-pressed on the L2 laminated copper foil through an adhesive sheet P22; the L5 laminated copper foil is hot-pressed on the L4 laminated copper foil through an adhesive sheet P11, and the L6 laminated copper foil is hot-pressed on the L5 laminated copper foil through an adhesive sheet P12. In the present application, the adhesive sheet can be a semi-cured sheet.

[0024] The interlayer alignment structure 110 is provided between the copper-clad core board C and the L2 and L1 laminated copper foils, and between the copper-clad core board C and the L5 and L6 laminated copper foils. In the embodiment, as shown in Fig. 1, the interlayer alignment structure 110 can be arranged at the four corners of the HDI circuit board 100. Figure 1 As a variation of the embodiment, the interlayer alignment structure 110 can be arranged at the non-corner positions of at least two opposite sides of the HDI circuit board 100. Optionally, the interlayer alignment structure 110 is also arranged at the middle part of the HDI circuit board 100 to further improve the interlayer alignment accuracy.

[0025] The interlayer alignment structure 110 between the copper-clad core board C and the L2 and L1 laminated copper foils and between the copper-clad core board C and the L5 and L6 laminated copper foils has the same structure, and here the interlayer alignment structure 110 between the copper-clad core board C and the L5 and L6 laminated copper foils is taken as an example for description.

[0026] In combination with Figure 2 and Figure 3As shown, the interlayer alignment structure 110 includes a reference copper disc 111 arranged in the L4 copper foil, a first alignment copper ring 112 arranged in the L5 laminated copper foil, and a second alignment copper ring 113 arranged in the L6 laminated copper foil; preferably, the reference copper disc 111 is a solid circular structure, and the diameter thereof can be 1mm-3mm, for example, 2mm. The inner diameters of the first alignment copper ring 112 and the second alignment copper ring 113 are both greater than the diameter of the reference copper disc 111, and the size of the second alignment copper ring 113 is greater than that of the first alignment copper ring 112; that is, the size of the reference copper disc 111 and the alignment copper rings of the laminated copper foils from the inner to the outer is gradually increased.

[0027] Specifically, the radial width (i.e. the difference between the inner and outer diameters) of the first alignment copper ring 112 and the second alignment copper ring 113 can be 0.2mm-0.5mm, for example, 0.3mm. As shown in the figure, Figure 3 As shown, from the thickness direction of the HDI circuit board 100, the reference copper disc 111, the first alignment copper ring 112 and the second alignment copper ring 113 are sequentially and spacedly arranged; that is, the reference copper disc 111 and the alignment copper rings of the laminated copper foils from the inner to the outer are sequentially and spacedly arranged. Preferably, the reference copper disc 111, the first alignment copper ring 112 and the second alignment copper ring 113 sequentially have a set spacing of 0.3mm-0.8mm (for example, 0.6mm).

[0028] The HDI circuit board 100 is provided with an observation hole 120 for exposing the reference copper disc 111 and the alignment copper ring in the inner laminated copper foil, and the relative positions between the reference copper disc 111 and each alignment copper ring can be visually inspected from the observation hole 120, so as to determine whether the product is interlayerly deviated. In the embodiment, the L5 laminated copper foil is the inner laminated copper foil, the L6 laminated copper foil is the outer laminated copper foil, and the HDI circuit board 100 is provided with an observation hole 120 for exposing the reference copper disc 111 and the first alignment copper ring 112.

[0029] Further, one or more positioning targets (not shown in the figure) are respectively arranged in each laminated copper foil of the HDI circuit board 100, and the positioning targets are used as the position reference of the conductive circuit and the alignment copper ring in the laminated copper foil, and the positioning targets themselves take the reference copper disc 111 as the position reference. Specifically, after the L5 laminated copper foil is hot-pressed, the area corresponding to the reference copper disc 111 of the L5 laminated copper foil and the P11 adhesive sheet is first laser ablated to expose the reference copper disc 111, then the positioning target is processed in the L5 laminated copper foil with the reference copper disc 111 as the reference, and the interlayer interconnection hole of the L5 laminated copper foil and the L4 copper foil is made with the positioning target as the position reference, and the L5 laminated copper foil is etched with the positioning target as the position reference, so as to obtain the conductive circuit and the first alignment copper ring 112 of the L5 laminated copper foil.

[0030] After the L6 compression copper foil is compressed, the area of the L6 compression copper foil and the P12 adhesive sheet corresponding to the reference copper disc 111 is ablated by laser to expose the reference copper disc 111 and the first alignment copper ring 112, thereby obtaining the observation hole 120 of the embodiment. Then, the positioning target is processed in the L6 compression copper foil with the reference copper disc 111 as the reference, the interlayer interconnection hole of the L6 compression copper foil and the L5 compression copper foil is made with the positioning target as the position reference, and the L6 compression copper foil is etched with the positioning target as the position reference, thereby obtaining the conductive circuit of the L6 compression copper foil and the second alignment copper ring 113.

[0031] In the HDI circuit board 100 of the embodiment, the L4 copper foil of the copper-clad core plate C is provided with the reference copper disc 111, the positions corresponding to the reference copper disc 111 in the L5 and L6 compression copper foils are respectively provided with the first alignment copper ring 112 and the second alignment copper ring 113, and the reference copper disc 111 and the first alignment copper ring 112 are exposed from the observation hole 120, so that the relative positions between the reference copper disc 111 and each alignment copper ring can be visually observed from the observation hole 120, and whether the conductive circuit of each layer of the product is interlayerly deviated can be judged.

[0032] Although the utility model is disclosed as above with specific embodiments, these specific embodiments are not used to limit the implementation range of the utility model. Any person skilled in the art can make some changes / replacements without departing from the scope of the utility model, and any equivalent changes made according to the utility model should be covered by the protection range of the utility model.

Claims

1. An HDI circuit board comprising a copper-clad core board and a plurality of laminated copper foils connected in series to at least one surface side of the copper-clad core board through an adhesive sheet; characterized in that, The copper-clad core board is provided with an interlayer alignment structure between the copper-clad core board and the multilayered copper foil, and the interlayer alignment structure comprises: a reference copper disc provided in the copper foil of the copper-clad core board itself; an alignment copper ring provided in the corresponding position of the reference copper disc in each layer of the copper foil; wherein the inner diameter of the alignment copper ring in each layer of the copper foil is greater than the outer diameter of the reference copper disc, and the size of the alignment copper ring in each layer of the copper foil gradually increases from inside to outside; wherein the HDI circuit board is provided with an observation hole for exposing the reference copper disc and the alignment copper ring in the inner layer of the copper foil.

2. The HDI circuit board of claim 1, wherein: Each layer of the copper foil is provided with a positioning target point, which serves as a position reference for the conductive circuit and the alignment copper ring in each layer of the copper foil.

3. The HDI circuit board of claim 1, wherein: From the thickness direction of the HDI circuit board, the reference copper disc and the alignment copper rings are sequentially and separately arranged.

4. The HDI circuit board of claim 1, wherein: The reference copper disc has a solid circular structure.

5. The HDI circuit board of claim 4, wherein: The diameter of the reference copper disc is 1mm-3mm.

6. The HDI circuit board of claim 1, wherein: The radial width of the alignment copper ring is 0.2mm-0.5mm.

7. The HDI circuit board of claim 1, wherein: The interlayer alignment structure is arranged at the four corner portions of the HDI circuit board.

8. The HDI circuit board of claim 1, wherein: The interlayer alignment structure is arranged at at least two opposite sides of the HDI circuit board.

9. The HDI circuit board of claim 7 or 8, wherein: The interlayer alignment structure is also arranged at the middle portion of the HDI circuit board.

10. The HDI circuit board of claim 1, wherein: Both opposite surface sides of the copper-clad core board are provided with multilayered copper foils, and the interlayer alignment structure is arranged between the copper-clad core board and the multilayered copper foils on both opposite surface sides of the copper-clad core board.

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