A metal-based FR4 hybrid pressing substrate and its production method

Abstract

The present invention discloses a metal-based FR4 hybrid pressing substrate and a production method thereof. The metal-based FR4 hybrid pressing substrate includes a metal base layer, an adhesive layer, an FR4 base material layer, and a circuit layer that are sequentially stacked from bottom to top. One end of the metal base layer extends outwards beyond the FR4 base material layer, and one end of the FR4 base material layer and the circuit layer extends outwards beyond the adhesive layer, so that the overlapping area between the upper and lower parts of the FR4 base material layer and the metal base layer is bonded together through the adhesive layer. In the present invention, through the structure where only the overlapping part of the metal base and the FR4 substrate is provided, a stepped metal substrate with a staggered arrangement is formed between the two. Its structure is special and suitable for the position space specially designed for special equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of printed circuit board manufacturing, and particularly relates to a metal-based FR4 hybrid substrate and a production method thereof. Background Art

[0002] At present, with the development of the electronics industry, high-power and high-current electronic products are increasingly widely used, and the requirements for circuit boards as carriers of electronic components are also getting higher and higher.

[0003] In the current industry, metal substrates are generally formed by pressing FR4 and metal substrates with equal areas, and the entire substrate is of uniform thickness. For some specially designed devices, the positions and spaces for placing the PCB substrates are relatively special, and ordinary substrates with uniform thickness cannot be placed. Summary of the Invention

[0004] In view of the above-mentioned existing technical defects, the present invention provides a metal-based FR4 hybrid substrate. Through the structure of only the overlapping part regions of the metal base and the FR4 substrate, a stepped metal substrate with a staggered arrangement is formed between the two. Its structure is special and suitable for the position spaces with special designs of special devices.

[0005] To solve the above technical problems, the present invention provides a metal-based FR4 hybrid substrate, which includes a metal base layer, an adhesive layer, an FR4 base material layer, and a circuit layer that are sequentially stacked from bottom to top. One end of the metal base layer extends out of the FR4 base material layer, and one end of the FR4 base material layer and the circuit layer extends out of the adhesive layer, so that the upper and lower overlapping regions of the FR4 base material layer and the metal base layer are bonded together through the adhesive layer.

[0006] Further, a groove is provided at the position of the metal base layer corresponding to the adhesive layer.

[0007] Further, the depth of the groove is 15 - 25 μm.

[0008] Further, the metal-based FR4 hybrid substrate further includes a through hole that sequentially penetrates the circuit layer, the FR4 base material layer, the adhesive layer, and the metal base layer from top to bottom.

[0009] Further, the metal-based FR4 hybrid substrate further includes a solder mask layer provided on the circuit layer.

[0010] Further, the metal base is a copper base or an aluminum base.

[0011] Further, the adhesive sheet is a non-flowing glue PP sheet.

[0012] The present invention also provides a production method of a metal-based FR4 hybrid substrate, which includes the following steps:

[0013] S1. Cut out metal substrates, non-flowing glue PP sheets, and FR4 substrates with the same length and width specifications through blanking.

[0014] S2. Control the depth of the router to cut out a groove in the area of the metal substrate that overlaps with the FR4 substrate later, and then cut out a slot on the metal substrate on one side of the groove. One side edge of the slot coincides with one side edge of the groove.

[0015] S3. Use the negative film process to make circuits on one surface of the FR4 substrate, and etch off all the copper layers on the other surface. Then, successively perform solder mask layer production and surface treatment on the FR4 substrate.

[0016] S4. Perform window openings at corresponding positions on the FR4 substrate and the non-flowing glue PP sheet respectively.

[0017] S5. Press the metal substrate and the FR4 substrate together through the non-flowing glue PP sheet to form a production board. Among them, the window openings on the FR4 substrate and the non-flowing glue PP sheet correspond up and down.

[0018] S6. Then drill through holes on the production board.

[0019] S7. Cut the inner non-flowing glue PP sheet at the edge of the groove through the slot on the metal substrate to expose the inner FR4 substrate layer.

[0020] S8. Remove the parts on the production board other than the window openings and the slots through shaping.

[0021] S9. Finally, remove the remaining non-flowing glue PP sheet at the position of the slot on the production board to obtain a metal-based FR4 co-pressed substrate.

[0022] Further, the following steps are also included between steps S1 and S2:

[0023] S11. First, drill first riveting holes at corresponding positions on the edges of the FR4 substrate, the metal substrate, and the non-flowing glue PP sheet respectively, and drill second riveting holes with diameters smaller than the through hole diameter at the corresponding positions of the later drilled through holes in the three.

[0024] Further, in step S5, before pressing, first rivet and fix the metal substrate, the non-flowing glue PP sheet, and the FR4 substrate together through rivets passing through the riveting holes. Among them, metal rivets are used for riveting in the first riveting holes, and bamboo / wood dowels are used for riveting in the second riveting holes.

[0025] Further, in step S2, control the depth of the router to cut out a groove with a depth of 15 - 25 μm.

[0026] Further, in step S4, the window opening on the non-flowing glue PP sheet is 0.1 mm larger than the window opening on the FR4 substrate on one side.

[0027] Further, in step S7, the non-flowing glue PP sheet of the inner layer is cut by laser or blade.

[0028] Further, in step S9, the remaining non-flowing glue PP sheet is removed by direct stripping and blade cutting.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] Through the structure in which only the overlapping part regions of the metal base and the FR4 substrate are arranged, a stepped metal substrate with misalignment setting and uneven equal thickness is formed between the two. Its structure is special and suitable for the position space of special design of special equipment. In addition, the grooves provided on the metal base layer can roughen the groove regions, improving the bonding force between the metal base layer and the bonding layer.

[0031] A specific production method is also provided. The structure of the metal base FR4 co-pressing substrate in the above is special and difficult to manufacture. The method of the present invention gives the entire manufacturing process, and can effectively and efficiently manufacture a qualified metal base FR4 co-pressing substrate. In this method, the surface of the metal base base is roughened by milling grooves. Compared with the prior art methods of local chemical roughening (which needs to go through film pasting, micro-etching, and film stripping in sequence) or local physical roughening (roughening by grinding the board), the method of milling grooves can, first, reduce the processes of chemical roughening to improve production efficiency, and second, avoid the quality problem of the metal base being bent during the local physical roughening process, improving the production quality. In addition, non-flowing glue PP sheets are used for lamination, reducing the flowing glue for window opening and slotting, and facilitating the later removal of the non-flowing glue PP sheets at the metal base platform and the FR4 platform. Also, the window openings on the non-flowing glue PP sheets are made larger than those on the FR4 substrate, preventing the flowing glue on the non-flowing glue PP sheets from overflowing to the outer surface of the FR4 substrate during lamination, and ensuring that the circuit layer on the FR4 substrate is not contaminated by the flowing glue. Second riveting holes with diameters smaller than the through-hole diameters are drilled at the corresponding positions of the later drilled through-holes among the FR4 substrate, the metal base, and the non-flowing glue PP sheets, and bamboo / wood dowels are used for riveting at these riveting holes during later riveting. In this way, the bamboo / wood dowels can be removed simultaneously during the later drilling of the through-holes, avoiding the need to remove metal dowels first before drilling when using metal dowels, and also avoiding the problem that the quality of the board is easily affected during the removal of the metal dowels, such as the circuit on the board surface being scratched. Thus, the method of the present invention effectively improves the production efficiency and production quality.

[0032] Additional aspects and advantages of the present invention will be given in part in the following description, which will become apparent from the following description, or can be understood through the practice of the present invention. Description of the Drawings

[0033] Figure 1 It is a schematic diagram of the metal base FR4 co-pressing substrate in Embodiment 1;

[0034] Figure 2 It is a schematic diagram of the manufacturing process of the metal-based FR4 hybrid substrate in Example 2. Detailed implementation manners

[0035] In order to more fully understand the technical content of the present invention, the present invention will be further introduced and described below in conjunction with the drawings and specific embodiments; it should be noted that in the text, if there are descriptions such as "first", "second", etc., they are used to distinguish different components, etc., and do not represent the sequence, nor do they limit that "first" and "second" are different types.

[0036] Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all embodiments; based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present invention.

[0037] Example 1

[0038] As Figure 1 shown, a metal-based FR4 hybrid substrate shown in this embodiment includes a metal base layer 1, an adhesive layer 2, an FR4 base material layer 3, and a circuit layer 4 that are stacked in sequence from bottom to top. One end of the metal base layer 1 extends outwards beyond the FR4 base material layer 3 to form a metal base platform 10. One end of the FR4 base material layer 3 and the circuit layer 4 extends outwards beyond the adhesive layer 2 and the metal base layer 1 to form an FR4 platform 31. Moreover, the extending directions of the metal base layer and the FR4 base material layer are different, so that only a partial area of the FR4 base material layer 3 and the metal base layer 1 overlap, and the overlapping area between the two is bonded together through the adhesive layer 2; in the above, through the structure of only overlapping partial areas of the metal base and the FR4 substrate, a stepped metal substrate with a staggered arrangement and uneven thickness is formed between the two. Its structure is special and suitable for the position space of special designs of special equipment.

[0039] Specifically, a groove 11 is provided at the position of the metal base layer 1 corresponding to the adhesive layer 2. By providing the groove on the metal base layer, the groove area can be roughened, improving the bonding force between the metal base layer and the adhesive layer.

[0040] Specifically, the depth of the groove 11 is 15-25 μm, which can roughen the bonding area while avoiding the groove being too deep and affecting the later glue filling quality.

[0041] In this embodiment, the metal-based FR4 hybrid substrate further includes a through hole 6 that penetrates the circuit layer 4, the FR4 base material layer 3, the adhesive layer 2, and the metal base layer 1 in sequence from top to bottom. The through hole is a mounting hole or a fixing hole for fixing the metal-based FR4 hybrid substrate on the corresponding machine equipment.

[0042] Specifically, the metal-based FR4 hybrid substrate further includes a solder mask layer 5 provided on the circuit layer 4 for protecting the circuit layer.

[0043] In other embodiments, the metal base is a copper base or an aluminum base.

[0044] In other embodiments, the adhesive sheet is a non-flowing glue PP sheet.

[0045] In other embodiments, the solder mask layer only covers part of the circuit layer, and a nickel-gold layer is plated on the other uncovered circuit layers to prevent the circuit layer from being oxidized.

[0046] Embodiment 2

[0047] As Figure 2 shown, a production method of a metal-based FR4 hybrid substrate shown in this embodiment is used to manufacture the metal-based FR4 hybrid substrate described in Embodiment 1, and successively includes the following processing steps:

[0048] (1) Blanking: Cut out the metal base, FR4 substrate, and PP sheet according to the panel size of 520 mm × 620 mm. The thickness of the FR4 substrate is 0.5 mm (excluding the thickness of the outer copper layer), and the thickness of the copper layers on both sides of the FR4 substrate is 0.5 oz or 1 oz.

[0049] (2) Drilling: First, drill the first riveting holes at the corresponding positions on the edges of the FR4 substrate, metal base, and non-flowing glue PP sheet respectively, and drill the second riveting holes with a diameter smaller than the through-hole diameter at the corresponding positions of the later through-holes in the three.

[0050] (3) Metal base grooving and slotting: Use a milling machine to control the depth and mill a groove with a depth of 15 - 25 μm in the area of the metal base that will overlap with the FR4 substrate later. Then, open a slot hole on the metal base on one side of the groove. The position of the slot hole corresponds to the FR4 platform formed by the later outward extension and exposure of the FR4 substrate. One side edge of the slot hole coincides with one side edge of the groove, that is, the slot hole and the groove are adjacent to each other.

[0051] (4) Circuit manufacturing (negative film process): Coat a photosensitive film on the FR4 substrate with a vertical coater, control the film thickness of the photosensitive film to 8 μm, use a full-automatic exposure machine, and complete circuit exposure on one surface of the FR4 substrate with 5 - 6 exposure scales (21 exposure scales). The other surface of the FR4 substrate is not exposed. After development, a circuit pattern is formed; inner layer etching: Etch out the circuit on one surface of the FR4 substrate after exposure and development, and the same side of the other surface is completely etched away to expose the FR4 substrate layer, and then the film is removed.

[0052] (5) Make solder mask and silk screen characters: After spraying solder mask ink on the surface of the circuit layer of the FR4 substrate except at the solder mask opening positions, and successively undergoing pre-curing, exposure, development, and thermal curing treatments, the solder mask ink is cured into a solder mask layer. And spray-print the solder mask ink on the TOP surface, and add the "UL mark" to the TOP surface characters, so as to coat a protective layer on the circuits and substrates that do not need to be soldered to prevent bridging between circuits during soldering, provide a permanent electrical environment, and resist chemical corrosion, and at the same time play a role in beautifying the appearance.

[0053] (6) Surface treatment (immersion nickel and gold): The copper surface of the pads at the solder mask openings is uniformly deposited with a nickel layer and a gold layer of a certain required thickness through chemical principles. The thickness of the nickel layer is: 3 - 5 μm; the thickness of the gold layer is: 0.05 - 0.1 μm.

[0054] (7) Window opening: Window openings are respectively made at the corresponding positions of the FR4 substrate and the non-flowing glue PP sheet. The window opening positions correspond to the metal base platforms formed by the outward extension and exposure of the later metal base. Among them, the unilateral size of the window opening on the non-flowing glue PP sheet is 0.1 mm larger than that on the FR4 substrate, to prevent the flowing glue on the non-flowing glue PP sheet from overflowing to the outer surface of the FR4 substrate during the lamination process, and ensure that the circuit layer on the FR4 substrate is not contaminated by the flowing glue.

[0055] (8) Lamination: The metal base and the FR4 substrate are first subjected to blackening or browning treatment. The browning speed is based on the thickness of the bottom copper. After sequentially laminating the FR4 substrate and the metal base through the non-flowing glue PP sheet as required (the specific lamination order is: FR4 substrate, non-flowing glue PP sheet, metal base), a production board is formed. Among them, the window openings on the FR4 substrate and the non-flowing glue PP sheet correspond up and down; and before lamination, the three are riveted and fixed together by using rivets to pass through the riveting holes to avoid the problem of misalignment. Among them, metal rivets are used for riveting in the first riveting hole, and bamboo / wood dowels are used for riveting in the second riveting hole. In this way, the bamboo / wood dowels can be removed simultaneously during the later process of drilling through holes, avoiding the need to remove metal dowels first when using metal dowels, and it is also easy to affect the quality of the board during the process of removing metal dowels, such as scratching the circuit on the board surface. Thus, the method of the present invention effectively improves the production efficiency and product quality.

[0056] (9) Drilling: The production board is first subjected to de-blackening or de-browning treatment to remove the browning layer or blackening layer on the production board, and then drilling processing is carried out using drilling data, so as to coaxially drill through holes at the second riveting hole on the production board, and remove the bamboo / wood dowels in the second riveting hole while drilling through holes.

[0057] (10) Cutting: Cut the inner non-flowing glue PP sheet at the edge of the groove through the slot holes on the metal base, so that the non-flowing glue PP sheet is disconnected and the inner FR4 substrate layer is exposed. Laser or blade cutting is used during cutting.

[0058] (11) Electrical testing: Test the electrical conductivity of the finished board. The testing method used for this board is: flying probe testing.

[0059] (12) Shaping: According to the existing technology and design requirements, mill the outer shape. The outer shape tolerance is + / -0.05 mm. Remove the parts on the production board other than the openings and slots through shaping to expose the metal base platform at the openings.

[0060] (13) Glue removal: Finally, remove the residual non-flowing glue PP sheets at the slot positions on the production board by direct stripping and blade cutting to expose the FR4 platform, and obtain a metal-based FR4 co-pressed substrate with uneven thickness.

[0061] (14) FQC: According to the customer acceptance standard and our company's inspection standard, inspect the appearance of the finished board. Repair any defects in a timely manner to ensure excellent quality control for the customer.

[0062] (15) FQA: Re-inspect whether the appearance, hole copper thickness, dielectric layer thickness, solder mask thickness, inner layer copper thickness, etc. of the finished board meet the customer's requirements.

[0063] (16) Packaging: Package the finished board in a sealed manner according to the packaging method and quantity required by the customer, and place desiccants and humidity cards, then ship the product.

[0064] In other embodiments, the metal base is a copper base or an aluminum base.

[0065] The technical solutions provided by the embodiments of the present invention have been introduced in detail above. Specific examples are used in this article to elaborate on the principles and implementation manners of the embodiments of the present invention. The descriptions of the above embodiments are only applicable to help understand the principles of the embodiments of the present invention; at the same time, for those of ordinary skill in the art, based on the embodiments of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A production method of a metal-based FR4 hybrid laminate substrate, characterized in that, It includes the following steps: S1. Cut out metal substrates, non-flowing glue PP sheets, and FR4 substrates with the same length and width specifications; S2. At the area on the metal substrate that will overlap with the FR4 substrate later, control the depth of the milling to cut out a groove, and then cut out a slot on the metal substrate on one side of the groove. The position of the slot corresponds to the FR4 platform formed by the outward extension and exposure of the later FR4 substrate. One side edge of the slot coincides with one side edge of the groove; S3. Use the negative film process to make circuits on one surface of the FR4 substrate, and etch off all the copper layers on the other surface. Then, sequentially perform solder mask layer production and surface treatment on the FR4 substrate; S4. Open windows at corresponding positions on the FR4 substrate and the non-flowing glue PP sheet. The window positions correspond to the metal substrate platforms formed by the outward extension and exposure of the later metal substrate; S5. Press the metal substrate and the FR4 substrate together through the non-flowing glue PP sheet to form a production board. Among them, the windows on the FR4 substrate and the non-flowing glue PP sheet correspond up and down; S6. Then drill through holes on the production board; S7. Cut the inner non-flowing glue PP sheet at the edge of the groove through the slot on the metal substrate to expose the inner FR4 substrate layer; S8. Remove the parts other than the windows and slots on the production board through shaping; S9. Finally, remove the remaining non-flowing glue PP sheet at the slot position on the production board to obtain a metal substrate FR4 co-pressed substrate.

2. The production method of the metal-based FR4 hybrid laminate substrate according to claim 1, wherein Between step S1 and step S2, the following steps are also included: S11. First, drill first riveting holes at corresponding positions on the edges of the FR4 substrate, the metal substrate, and the non-flowing glue PP sheet, and drill second riveting holes with diameters smaller than the through hole diameters at the positions corresponding to the later through holes in the three; 3. The production method of the metal-based FR4 hybrid laminate substrate according to claim 2, wherein, In step S5, before pressing, first rivet and fix the metal substrate, the non-flowing glue PP sheet, and the FR4 substrate together through the riveting holes. Among them, metal rivets are used for riveting in the first riveting holes, and bamboo / wood dowels are used for riveting in the second riveting holes; 4. The production method of the metal-based FR4 hybrid laminate substrate according to claim 1, characterized in that In step S2, use a milling machine to control the depth of the milling to cut out a groove with a depth of 15 - 25 μm; 5. The production method of the metal-based FR4 hybrid laminate substrate according to claim 1, characterized in that, In step S4, the unilateral size of the window on the non-flowing glue PP sheet is 0.1 mm larger than the window on the FR4 substrate.

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