A processing structure of a resin-filled buried hole HDI circuit board

Abstract

The utility model is applicable to the technical field of printed circuit board production, and provides a processing structure of a resin-plugged buried hole HDI circuit board, including an HDI circuit board body, wherein the HDI circuit board body includes an outer layer, a sub-outer layer, an inner core board, a dielectric layer, buried holes, plugging hole resin, buried hole disks and non-functional buried hole disks, and the blanks of the inner core board lacking buried hole disks are filled with non-functional buried hole pads. The utility model changes the structure of the dielectric layer around the buried holes and reduces the volume of the dielectric layer around the buried holes by filling the blanks of the inner core board lacking buried hole disks with non-functional buried hole disks, and at the same time limits the thermal expansion of the dielectric layer around the buried holes with the non-functional buried hole disks of the inner layer of the buried holes, so that the thermal expansion size of the dielectric layer is as close as possible to the thermal expansion size of the plugging hole resin and copper, improves the stress at the hole mouth position, reduces the probability of micro-cracks and delamination between the plugging hole resin and the dielectric layer of the HDI circuit board buried hole mouth, improves the yield rate of PCB products, and reduces production costs.

Description

Technical Field

[0001] The utility model belongs to the technical field of printed circuit board manufacturing, in particular to a processing structure of a resin-plugged buried hole HDI circuit board. Background Art

[0002] HDI is the abbreviation of High Density Interconnector, which is a type of printed circuit board that uses micro-blind buried hole technology to produce a circuit board with a relatively high line distribution density. The HDI board is designed with buried holes in the second outer layer. Before lamination of the outer layer, the buried holes in the second outer layer need to be filled with resin plug holes and then laminated to complete the laminated board. Due to the large expansion coefficient of the dielectric layer and the small expansion coefficients of the plug hole resin and copper, the three expand inconsistently when the board is heated, resulting in stress concentration at the hole mouth. When the stress at the hole mouth reaches a certain level, it is easy to cause micro cracks and delamination at the hole mouth of the printed circuit board. For this reason, a processing structure of a resin plug buried hole HDI circuit board is proposed. Summary of the invention

[0003] The utility model aims to provide a processing structure of a resin-plugged buried hole HDI circuit board, aiming to solve the problems raised in the above-mentioned background technology.

[0004] The utility model is implemented in this way. A processing structure of a resin-plugged buried via HDI circuit board includes an HDI circuit board body, wherein the HDI circuit board body includes an outer layer, a sub-outer layer, an inner core board, a dielectric layer, buried vias, plugging resin, buried via pads and non-functional buried via pads, wherein the blank space of the inner core board lacking the buried via pads is filled with non-functional buried via pads, and the non-functional buried via pads are used to limit the dielectric layer around the buried vias.

[0005] Furthermore, the thickness of the non-functional buried via pad is the same as the thickness of the buried via pad and the copper foil in the layer where the non-functional buried via pad is located.

[0006] Furthermore, a gap is left between the non-functional buried via pad and the buried via pad of the layer where it is located, the copper sheet and the circuit.

[0007] Furthermore, the width of the gap is 0.4-1.2 mm.

[0008] Compared with the prior art, the beneficial effects of the utility model are:

[0009] The processing structure of the resin-plugged buried via HDI circuit board changes the structure of the dielectric layer around the buried via by filling the blank space where the inner core board lacks the buried via disc with a non-functional buried via disc, reduces the volume of the dielectric layer around the buried via, and limits the thermal expansion of the dielectric layer around the buried via by using the non-functional buried via disc in the inner layer of the buried via, so that the thermal expansion size of the dielectric layer is as close as possible to the thermal expansion size of the plugging via resin and copper, improves the stress at the hole mouth position, reduces the probability of micro cracks and delamination between the plugging via resin and the dielectric layer at the hole mouth of the HDI circuit board, improves the yield rate of PCB products, and reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the structure of the inner core plate in the prior art after the buried hole plate is pressed together;

[0011] Figure 2 It is a schematic diagram of the structure of the resin-filled buried hole HDI circuit board after the blank space of the inner core board lacking the buried hole pad is filled with non-functional buried hole pad after pressing;

[0012] In the figure: 1-buried via plate, 2-non-functional buried via plate, 3-dielectric layer, 4-hole plugging resin, 5-buried via. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0014] The specific implementation of the present utility model is described in detail below in conjunction with specific embodiments.

[0015] like Figure 2 As shown, a processing structure of a resin-plugged buried via HDI circuit board provided by an embodiment of the utility model includes an HDI circuit board body, wherein the HDI circuit board body includes an outer layer, a sub-outer layer, an inner core board, a dielectric layer 3, buried vias 5, plugging resin 4, a buried via plate 1 and a non-functional buried via plate 2, wherein the blank space of the inner core board lacking the buried via plate 1 is filled with a non-functional buried via pad 2, and the non-functional buried via plate 2 is used to limit the dielectric layer 3 around the buried via 5.

[0016] like Figure 2 As shown, as a preferred embodiment of the present invention, the thickness of the non-functional buried via plate 2 is the same as the thickness of the buried via plate 1 and the copper sheet in the layer where it is located.

[0017] like Figure 2 As shown, as a preferred embodiment of the utility model, a gap is left between the non-functional buried via pad 2 and the buried via pad 1 of the layer where it is located, the copper sheet and the circuit.

[0018] like Figure 2 As shown, as a preferred embodiment of the present invention, the width of the gap is 0.4-1.2 mm.

[0019] In the embodiment of the present utility model, it is preferably 0.8 mm.

[0020] An embodiment of the present invention provides a method for processing a resin-plugged buried via HDI circuit board, comprising the following steps:

[0021] S1, PCB design stage, fill the blank space where the buried via pad 1 is missing in each inner core board with a non-functional buried via pad 2, and fill the blank space where the buried via pad 1 is missing in the inner core board with a non-functional buried via pad 2, change the substrate structure around the buried via 5, reduce the volume of the dielectric layer 3 around the buried via 5, and use the non-functional buried via pad 2 in the inner layer of the buried via 5 to limit the expansion of the dielectric layer 3 around the buried via 5, so that its thermal expansion size is as close as possible to the thermal expansion size of the plugging resin 4 and copper, improve the expansion coefficient of the dielectric layer 3 around the buried via 5 of the HDI board to be larger than the plugging resin 4 and copper, and then cause micro cracks and delamination between the plugging resin 4 and the dielectric layer 3 after heating, thereby reducing the probability of micro cracks and delamination inside the circuit board;

[0022] S2. After the design is completed, the material is cut and the inner core board is cut according to the size of the panel. The graphics of each inner core board are made, and then the inner core boards and copper foils are pressed together to form a core board with an inner layer and a sub-outer layer. The structural diagram is shown in the figure. Figure 2 As shown;

[0023] S3, drill buried holes in the core board with inner layer and sub-outer layer, according to the thickness of the core board with inner layer and sub-outer layer, use the drilling data to drill buried holes in the sub-outer layer of the circuit board; deposit copper in the sub-outer layer, and electroplate the whole board to make the copper layer thickness in the hole and on the surface of the sub-outer layer 20~40μm; bury and plug the hole with resin 4, grind the plugging resin 4; make the sub-outer layer pattern, use the exposure machine to expose the sub-outer layer circuit, and develop it; acid etch the outer layer; then press it with the copper foil, the structural diagram after pressing is as shown Figure 2 As shown;

[0024] S4, outer layer drilling, according to the thickness of the circuit board, use the drilling data to drill the outer layer of the circuit board; the outer layer is copper-plated, and the whole board is electroplated to make the copper layer thickness inside the hole and on the surface of the PCB 20~40μm;

[0025] S5, outer layer pattern production, use 6-grid exposure ruler or 21-grid exposure ruler to complete outer layer circuit exposure, and develop; acid outer layer etching;

[0026] S6, screen printing solder mask, use 9~13 grid exposure ruler for exposure;

[0027] S7, nickel-gold immersion for the whole board, post-process.

[0028] The above are only preferred implementations of the utility model. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the utility model. These should also be regarded as the protection scope of the utility model. These will not affect the effect of the implementation of the utility model and the practicality of the patent.

Claims

1. A processing structure of a resin-filled buried hole HDI circuit board, comprising an HDI circuit board body, characterized in that: The HDI circuit board body includes an outer layer, a sub-outer layer, an inner core board, a dielectric layer, buried vias, plugging resin, buried via pads and non-functional buried via pads. The blank spaces of the inner core board lacking buried via pads are filled with non-functional buried via pads. The non-functional buried via pads are used to limit the dielectric layer around the buried vias.

2. The processing structure of the resin plug buried hole HDI circuit board according to claim 1 is characterized in that: The thickness of the non-functional buried via pad is the same as the thickness of the buried via pad and the copper sheet in the layer where the non-functional buried via pad is located.

3. The processing structure of the resin plug buried hole HDI circuit board according to claim 1 is characterized in that: A gap is left between the non-functional buried via pad and the buried via pads of the layer where it is located, the copper sheet and the circuit.

4. The processing structure of the resin plug buried hole HDI circuit board according to claim 3 is characterized in that: The width of the gap is 0.4-1.2 mm.

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