PCB drilling method and PCB

Abstract

The present application relates to the technical field of printed circuit boards, and provides a PCB drilling method and a PCB, the PCB drilling method comprising: providing a substrate, the substrate having a first surface and a second surface opposite to each other, a heat dissipation copper block embedded in the substrate; drilling a first hole on the substrate from the first surface, the axis of the first hole being perpendicular to the first surface, the first hole penetrating the first surface and not penetrating the second surface; drilling a second hole on the substrate from the second surface, the aperture of the second hole being greater than or equal to the aperture of the first hole, the second hole penetrating the first surface and the second surface at the same time. The PCB drilling method of the present application can reduce the occurrence of flash and hole wall separation at the hole mouth and hole wall of the via hole after drilling the via hole on the PCB embedded with the heat dissipation copper block, and the problem of board explosion and delamination after being heated through the finished product tin spraying process, reflow soldering process and wave soldering process.

Description

Technical Field

[0001] The present application relates to the technical field of printed circuit boards, and in particular to a PCB drilling method and a PCB. Background Art

[0002] In order to meet the needs of high heat dissipation, in the design of PCB products, embedded heat dissipation copper blocks will be used in the areas that need high heat dissipation within the PCB product unit to achieve the effect of local high heat dissipation. Some PCB products are also designed with conductive holes around the embedded heat dissipation copper blocks. These conductive holes mainly play the role of conduction between layers.

[0003] In the traditional processing technology, after drilling the via holes on the PCB embedded with the heat dissipation copper block, flash and hole wall separation will appear at the hole mouth and hole wall. Some PCBs may even explode and delaminate after being heated in the finished product tin spraying process, reflow soldering process and wave soldering process after drilling the via holes, resulting in poor PCB quality. Summary of the invention

[0004] The present application provides a PCB drilling method and a PCB, so as to reduce the flash and hole wall separation at the hole mouth and hole wall of the via hole after drilling the via hole on the PCB embedded with the heat dissipation copper block, and the problem of board explosion and delamination after being heated through the finished product tin spraying process, reflow soldering process and wave soldering process.

[0005] An embodiment of the first aspect of the present application provides a PCB drilling method, comprising:

[0006] Provide a substrate, the substrate having a first surface and a second surface opposite to each other, and a heat dissipation copper block embedded in the substrate;

[0007] Drilling a first hole on the substrate from the first surface, wherein the axis of the first hole is perpendicular to the first surface, and the first hole passes through the first surface but does not pass through the second surface;

[0008] A second hole is drilled on the substrate from the second surface, the second hole is coaxially arranged with the first hole, the aperture of the second hole is greater than or equal to the aperture of the first hole, and the second hole passes through the first surface and the second surface at the same time.

[0009] In some embodiments, after providing a substrate and before drilling a first hole on the substrate from the first surface, the PCB drilling method further includes: placing the substrate on a pad, the pad having a bearing surface, and the second surface of the substrate is located on the bearing surface.

[0010] In some embodiments, after drilling a first hole on the substrate from the first surface and before drilling a second hole on the substrate from the second surface, the PCB drilling method further includes: placing the substrate on a pad, the pad having a bearing surface, and the first surface of the substrate is located on the bearing surface.

[0011] In some embodiments, the diameter of the second hole is 0.05 mm to 0.20 mm larger than the diameter of the first hole.

[0012] In some embodiments, a depth of the first hole is 1 / 5-4 / 5 of the distance between the first surface and the second surface.

[0013] In some embodiments, a plurality of the heat dissipation copper blocks are disposed on the substrate, and the first hole is located between two adjacent heat dissipation copper blocks.

[0014] In some embodiments, after drilling a second hole on the substrate from the second surface, the PCB drilling method further includes:

[0015] Copper cladding: plating the hole opening and the hole wall of the second hole to form a PTH hole;

[0016] Pulse plating: thickens the plating layer.

[0017] In some of the embodiments, after the pulse plating, the substrate is back-drilled.

[0018] In some embodiments, after the substrate is back-drilled, the substrate is sprayed with tin.

[0019] An embodiment of the second aspect of the present application provides a PCB, which is processed by the PCB drilling method as described in the first aspect.

[0020] The PCB drilling method provided in the embodiment of the present application has the beneficial effect that: since the first hole is firstly drilled on the substrate from the first surface, the first hole passes through the first surface but not the second surface, and then the second hole is drilled on the substrate from the second surface, the second hole is coaxially arranged with the first hole, the aperture of the second hole is greater than or equal to the aperture of the first hole, and the second hole passes through the first surface and the second surface at the same time, the pressure and force area of ​​the second drill bit when drilling the second hole can be reduced, and the temperature of the second drill bit can be reduced, which effectively avoids the substrate being unable to be effectively supported during drilling due to the protrusion of the heat dissipation copper block from the first surface and the second surface, resulting in the substrate being suspended during drilling, causing the hole mouth and hole wall of the second hole to have flash, hole wall separation and hole wall cracks, etc., and avoids the problem of board explosion and delamination after the substrate is heated after subsequent finished product tin spraying process, reflow soldering process and wave soldering process.

[0021] The beneficial effects of the PCB provided in the present application compared with the prior art are the same as the beneficial effects of the PCB drilling method provided in the present application compared with the prior art, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 is a flow chart of a PCB drilling method in one of the embodiments of the present application;

[0024] Figure 2 (a) is a schematic diagram of the structure of a substrate and a first drill bit in one embodiment of the present application;

[0025] Figure 2 (b) in the Figure 2 A top view of the substrate and the first drill bit shown in (a);

[0026] Figure 3 (a) in Figure 2 Schematic diagram of drilling a first hole on a substrate shown in (a);

[0027] Figure 3 (b) in the Figure 3 A top view of the substrate and the first drill bit shown in (a);

[0028] Figure 4 (a) in the formula is Figure 3 Schematic diagram of the substrate after flipping and the second drill bit shown in (a);

[0029] Figure 4 (b) in the Figure 4 A top view of the substrate and the second drill bit shown in (a);

[0030] Figure 5 (a) in Figure 4 Schematic diagram of drilling a second hole on the substrate shown in (a);

[0031] Figure 5 (b) in the Figure 5 A top view of the substrate and the second drill bit shown in (a);

[0032] Figure 6 (a) in Figure 5 Schematic diagram of a substrate after drilling a second hole on the substrate shown in (a);

[0033] Figure 6 (b) in the Figure 6 (a) is a top view of the substrate shown in FIG.

[0034] The meanings of the marks in the figure are:

[0035] 10. Base plate; 11. First surface; 12. Second surface; 13. Heat dissipation copper block; 14. First hole; 15. Second hole; 20. First drill bit; 30. Second drill bit. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0037] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0039] References to "one embodiment", "some embodiments" or "an embodiment" described in the specification of this application mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some other embodiments", "in some other embodiments", etc., which appear at different places in this specification, do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. In addition, in one or more embodiments, particular features, structures or characteristics may be combined in any suitable manner.

[0040] In order to illustrate the technical solution of the present application, a description is given below in conjunction with specific drawings and embodiments.

[0041] Please refer to Figure 1 , Figure 2 (a) and Figure 2In (b), an embodiment of the first aspect of the present application provides a PCB drilling method, comprising:

[0042] S100 : providing a substrate 10 , wherein the substrate 10 has a first surface 11 and a second surface 12 opposite to each other, and a heat dissipation copper block 13 is embedded in the substrate 10 .

[0043] Specifically, the substrate 10 may have gone through processes such as cutting, inner layer circuitry, inner layer AOI and lamination.

[0044] Cutting refers to cutting out the required inner core board size according to the required pressed structure.

[0045] Inner layer circuits refer to the circuits of each layer of the inner core board that are designed and manufactured according to the inner layer routing design.

[0046] Inner layer AOI refers to the full inspection of each inner layer circuit to see if it meets the product design requirements.

[0047] Pressing means that mixed pressing is not allowed in the same pressing opening, expansion and contraction are controlled at ±3mil, back drilling layer thickness is controlled at ±10%, and board thickness is controlled at ±5%.

[0048] Among them, since the substrate 10 is embedded with a heat dissipation copper block 13, due to the certain difference in thickness between the heat dissipation copper block 13 and the substrate 10, protrusions (with steps) will occur on one side or both sides of the embedded heat dissipation copper block 13, that is, it cannot be determined whether the heat dissipation copper block 13 will protrude from the first surface 11 or the second surface 12 or both the first surface 11 and the second surface 12. This makes it possible for the protruding part of the heat dissipation copper block 13 on the bottom surface of the substrate 10 to be suspended when drilling holes around the heat dissipation copper block 13. When drilling holes using conventional methods, serious problems such as hole burr, hole wall separation and hole wall cracks will occur due to excessive force on the drill tip and high heat. After being heated in the subsequent finished product tin spraying process, reflow soldering process and wave soldering process, the problem of board explosion and delamination will further occur.

[0049] S200 : drilling a first hole 14 on the substrate 10 from the first surface 11 , wherein the axis of the first hole 14 is perpendicular to the first surface 11 , and the first hole 14 passes through the first surface 11 but does not pass through the second surface 12 .

[0050] For details, please refer to Figure 3 (a) Figure 3 (b) Figure 5 (a) Figure 5 (b) Figure 6 (a) Figure 6 In (b), the substrate 10 can be placed on a pad having a bearing surface, and the second surface 12 of the substrate 10 is located on the bearing surface. Then, a first drill bit 20 is used to drill a first hole 14 on the substrate 10, and the first drill bit 20 does not drill through the substrate 10.

[0051] It is understandable that, since it cannot be determined whether the heat dissipation copper block 13 will protrude from the first surface 11 or the second surface 12 or both, the second surface 12 may not be completely fitted with the bearing surface. However, since the first hole 14 passes through the first surface 11 but not the second surface 12, the first drill bit 20 has a smaller processing area, is subjected to less force, and generates less heat.

[0052] It can be understood that the first hole 14 is a pre-drilled hole. On the one hand, this pre-drilled hole can reduce the force on the second drill bit 30 when drilling the second hole 15 later. On the other hand, pre-drilling is performed first to create a space in the second hole 15. When the second drilling is completed, the force area of ​​the second drill bit 30 during drilling can be reduced, and the heat generated by the second drill bit 30 during the second drilling can be reduced, thereby solving the current one-time drilling problem that the pressure of the drill bit pressing down is too high and the heat is too high due to the bottom surface of the substrate 10 being suspended, resulting in hole mouth flashing, hole wall separation and delamination and explosion.

[0053] S300: drilling a second hole 15 on the substrate 10 from the second surface 12 , the second hole 15 being coaxially arranged with the first hole 14 , the aperture of the second hole 15 being greater than or equal to the aperture of the first hole 14 , and the second hole 15 simultaneously passing through the first surface 11 and the second surface 12 .

[0054] For details, please refer to Figure 4 (a) and Figure 4 (b) in the figure can be produced by a drilling rig with Cpk≥1.33. First, the substrate 10 is turned over and placed on a pad having a bearing surface. The first surface 11 of the substrate 10 is located on the bearing surface. Then, a second drill bit 30 is used to drill a second hole 15 on the substrate 10. The second hole 15 passes through the substrate 10. The second hole 15 can be used as a conductive hole of the substrate 10.

[0055] It can be understood that since it is uncertain whether the heat dissipation copper block 13 will protrude from the first surface 11 or the second surface 12 or both, the first surface 11 or the second surface 12 may not be completely fitted with the bearing surface. However, since the first hole 14 has been drilled as a pre-drilled hole, the force on the second drill bit 30 is reduced when drilling the second hole 15, and the force-bearing area is also reduced, which can reduce the temperature of the second drill bit 30, thereby solving the current one-time drilling problem of excessive drilling pressure and excessive heat caused by the second drill bit 30 pressing down due to the suspension of the bottom surface of the substrate 10, resulting in hole mouth flashing, hole wall separation, and delamination and explosion.

[0056] It can be understood that the shapes of the first hole 14 and the second hole 15 can both be circular or elliptical.

[0057] The PCB drilling method provided in the embodiment of the present application is as follows: a first hole 14 is firstly drilled on the substrate 10 from the first surface 11, the first hole 14 penetrates the first surface 11 and does not penetrate the second surface 12, and then a second hole 15 is drilled on the substrate 10 from the second surface 12, the second hole 15 is coaxially arranged with the first hole 14, the aperture of the second hole 15 is greater than or equal to the aperture of the first hole 14, and the second hole 15 penetrates the first surface 11 and the second surface 12 at the same time, so when drilling the second hole 15, the pressure and force area of ​​the second drill bit 30 can be reduced, and the temperature of the second drill bit 30 can be reduced, and the substrate 10 can be effectively prevented from being unable to be effectively supported during drilling due to the protrusion of the heat dissipation copper block 13 from the first surface 11 and the second surface 12, resulting in the substrate 10 being suspended during drilling, causing the hole mouth and hole wall of the second hole 15 to have flashing, hole wall separation and hole wall cracks, etc., and the problem of board explosion and delamination after the substrate 10 is heated after the subsequent finished product tin spraying process, reflow soldering process and wave soldering process is avoided.

[0058] Please refer to Figure 5 (a) and Figure 5 (b) in which, in some embodiments, the diameter of the second hole 15 is 0.05mm-0.20mm larger than the diameter of the first hole 14, that is, the diameter of the second drill bit 30 is 0.05mm-0.20mm larger than the diameter of the first drill bit 20, such as 0.05mm, 0.10mm, 0.15mm and 0.20mm.

[0059] By adopting the above scheme, the alignment error between the second hole 15 and the first hole 14 can be eliminated, that is, a single-side offset tolerance of 0.025mm-0.10mm can be allowed when drilling the second hole 15, which meets the alignment accuracy requirements of the first hole 14 and the second hole 15, and can also eliminate slight drilling defects of the first hole 14, such as burr, hole wall separation and cracks.

[0060] Please refer to Figure 3 (a) and Figure 3 (b), in some embodiments, the depth of the first hole 14 is 1 / 5-4 / 5 of the distance between the first surface 11 and the second surface 12, such as 1 / 5, 2 / 5, 3 / 5 and 4 / 5.

[0061] By adopting the above solution, when drilling the first hole 14 , it is not necessary to perform particularly high-precision depth control, and the drilling of the first hole 14 can be completed, thereby making the first hole 14 more convenient to process.

[0062] Please refer to Figure 2 (a) and Figure 2 In (b), in some embodiments, a plurality of heat dissipation copper blocks 13 are disposed on the substrate 10, and the first hole 14 is located between two adjacent heat dissipation copper blocks 13. In this way, the heat dissipation effect of the substrate 10 can be better.

[0063] It can be understood that the second hole 15 is also located between the two heat dissipation copper blocks 13 .

[0064] In some embodiments, after drilling the second hole 15 on the substrate 10 from the second surface 12, the PCB drilling method further includes:

[0065] First, the copper plate is electroplated: a coating is plated at the hole opening and the hole wall of the second hole 15 to form a PTH hole.

[0066] Secondly, pulse plating: thickening the coating.

[0067] By adopting the above solution, PTH holes can be made on the substrate 10 to connect the circuits of each layer.

[0068] Optionally, after pulse plating, the substrate 10 is back-drilled, that is, the plating at the hole mouth and hole wall of the second hole 15 that does not play any connection or transmission role is drilled off to avoid reflection, scattering, delay, etc. of signal transmission, which may cause "distortion" to the signal. Back drilling can be performed using a special back drilling drill bit, and the depth control accuracy of the back drilling machine is controlled by ±0.05mm, and the Cpk capability must meet ≥1.33. The back drilling alignment is <0.075mm.

[0069] Optionally, after the substrate 10 is back-drilled, the substrate 10 is further processed with resin plugging, copper plate processing, outer layer circuits, outer layer etching, outer layer AOI, solder mask and text processing.

[0070] During the resin plugging process, the resin plugging holes are made normally, and the resin grinding is 100% passed through the resin plugging hole AOI inspection to confirm whether there are problems such as poor plugging and back drilling leakage.

[0071] The copper plate electrical process is produced normally, and the outer layer circuit process is etched normally.

[0072] During the outer layer etching process, the normal etching is performed and the line width and line spacing need to be controlled according to the parameters.

[0073] In the outer layer AOI process, 100% inspection is performed to confirm whether the outer layer circuit meets the product design requirements.

[0074] In the solder mask process, the silk screen solder mask surface oil, exposure and development are normally produced.

[0075] In the text process, the silk screen text is produced normally and then post-cured.

[0076] Optionally, the substrate 10 is subjected to tin spraying after the text process, and is produced according to normal tin spraying parameters, and attention should be paid to scratches. There is no need to reduce the tin spraying temperature, and there is no need to perform a baking process before tin spraying. In this way, the roughness and poor flatness of the surface of the substrate 10 after tin spraying caused by reducing the tin spraying temperature can be avoided, resulting in poor appearance and other problems, and the baking cost can also be reduced.

[0077] Optionally, after the substrate 10 is subjected to the tin spraying treatment, the substrate 10 may be further subjected to the following treatments:

[0078] First, gong plate: use gong cutter to gong out the size required by the customer.

[0079] Secondly, testing: Normally, it is required to test the insulation and conductivity of the PCB board.

[0080] Next, FQC: inspect the board according to the regular FQC inspection requirements.

[0081] Then, FQA: Inspect the board according to the regular FQA inspection requirements.

[0082] Finally, packaging: products that pass the inspection are packaged and shipped.

[0083] Please refer to Figure 6 (a) and Figure 6 (b) in the embodiment of the second aspect of the present application provides a PCB, which is processed by the PCB drilling method of the first aspect.

[0084] The PCB provided in the embodiment of the present application has a first hole 14 drilled on the substrate 10 from the first surface 11 during drilling, the first hole 14 penetrates the first surface 11 and does not penetrate the second surface 12, and then a second hole 15 is drilled on the substrate 10 from the second surface 12, the second hole 15 is coaxially arranged with the first hole 14, the aperture of the second hole 15 is greater than or equal to the aperture of the first hole 14, and the second hole 15 penetrates the first surface 11 and the second surface 12 at the same time, so when drilling the second hole 15, the pressure and force area of ​​the second drill bit 30 can be reduced, and the temperature of the second drill bit 30 can be reduced, effectively avoiding the substrate 10 being unable to be effectively supported during drilling due to the protrusion of the heat dissipation copper block 13 from the first surface 11 and the second surface 12, resulting in the substrate 10 being suspended during drilling, causing the hole mouth and hole wall of the second hole 15 to have flashing, hole wall separation and hole wall cracks, etc., avoiding the problem of board explosion and delamination after the substrate 10 is heated after the subsequent finished product tin spraying process, reflow soldering process and wave soldering process, so that the quality of the PCB is better.

[0085] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A PCB drilling method, characterized in that: include: Provide a substrate, the substrate having a first surface and a second surface opposite to each other, a heat dissipation copper block embedded in the substrate, and the heat dissipation copper block protruding from the first surface and / or the second surface; Drilling a first hole on the substrate from the first surface, wherein the axis of the first hole is perpendicular to the first surface, and the first hole passes through the first surface but does not pass through the second surface; A second hole is drilled on the substrate from the second surface, the second hole is coaxially arranged with the first hole, the aperture of the second hole is greater than or equal to the aperture of the first hole, and the second hole passes through the first surface and the second surface at the same time.

2. The PCB drilling method according to claim 1, characterized in that: Before drilling a first hole on the substrate from the first surface, the PCB drilling method further includes: placing the substrate on a pad, the pad having a bearing surface, and the second surface of the substrate is located on the bearing surface.

3. The PCB drilling method according to claim 1, characterized in that: After drilling a first hole on the substrate from the first surface and before drilling a second hole on the substrate from the second surface, the PCB drilling method further includes: placing the substrate on a pad, the pad having a bearing surface, and the first surface of the substrate is located on the bearing surface.

4. The PCB drilling method according to claim 1, characterized in that: The diameter of the second hole is 0.05 mm to 0.20 mm larger than the diameter of the first hole.

5. The PCB drilling method according to claim 1, characterized in that: The depth of the first hole is 1 / 5-4 / 5 of the distance between the first surface and the second surface.

6. The PCB drilling method according to claim 1, characterized in that: A plurality of the heat dissipation copper blocks are arranged on the substrate, and the first hole is located between two adjacent heat dissipation copper blocks.

7. The PCB drilling method according to any one of claims 1 to 6, characterized in that: After drilling a second hole on the substrate from the second surface, the PCB drilling method further includes: Copper cladding: plating the hole opening and the hole wall of the second hole to form a PTH hole; Pulse plating: thickens the plating layer.

8. The PCB drilling method according to claim 7, characterized in that: After pulse plating, the substrate is back drilled.

9. The PCB drilling method according to claim 8, characterized in that: After the substrate is back-drilled, the substrate is sprayed with tin.

10. A PCB, characterized in that: The PCB is processed by the PCB drilling method according to any one of claims 1 to 9.

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