Structure for solving hot zone cracks of PCB (Printed Circuit Board)
By adopting a mixed stacked structure of high-thermal semi-cured sheet and ordinary FR4 material on the PCB board, combined with copper layer and hole design, the problem of hot zone cracks during welding is solved, the reliability of the circuit board is improved and the cost is reduced. The economic benefits have been improved.
Patent Information
- Application Number
- CN202420491899.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-14
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2034-03-14
AI Technical Summary
Existing PCB boards are prone to hot zone cracks during welding, resulting in reduced circuit board performance and reliability, and there is no effective solution in the industry, resulting in increased manufacturing costs.
A special stacked structure consisting of several insulating dielectric layers and highly thermally conductive semi-cured layers is adopted. By using a highly thermally conductive semi-cured sheet in a key area, the thermal stress tolerance is enhanced by combining the copper layer and the hole structure.
It effectively solves the problem of hot zone cracks, reduces manufacturing costs, improves the reliability of circuit boards, and has a lower cost than fully used high-thermal conductive materials, which has a competitive advantage.
Smart Images
Figure CN222147885U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the relevant technical field of PCB boards, and particularly relates to a structure for solving cracks in a hot zone of a PCB. Background Art
[0002] PCB circuit board is one of the important components of the electronics industry. Almost every electronic device, from electronic watches and calculators to computers, communication electronic equipment, and military weapon systems, as long as there are electronic components such as integrated circuits, must use printed circuit boards to make electrical interconnections between the various components. The printed circuit board consists of an insulating base plate, connecting wires, and pads for assembling and welding electronic components. It has the dual functions of a conductive circuit and an insulating base plate.
[0003] Therefore, printed circuit boards are widely used. Since printed circuit boards need to be welded during processing, thermal cracks will occur. Thermal cracks are cracks generated during high temperature and molten pool solidification. They are the most common type of cracks in the welding process. From low carbon steel, low alloy high strength steel, to austenitic stainless steel, aluminum alloy and nickel-based alloy, there is the possibility of welding thermal cracks. Thermal cracks are most common in the center of the weld and are crystallization cracks. Their formation process is mainly related to low melting point eutectic and tensile stress. This type of crack can be observed under a microscope and has the characteristics of intergranular destruction. Most of the cracks have an oxidized color on the cross section. Thermal cracks mainly appear in welds containing more impurities (especially carbon steel welds containing more sulfur, phosphorus and carbon) and single-phase austenite or some aluminum alloy welds, and sometimes also in the heat affected zone. There are longitudinal and transverse ones, and the generation of thermal cracks will lead to a decrease in the electrical performance of the circuit board and a decrease in reliability.
[0004] At present, the industry has not completely and effectively solved the problem of hot zone cracks, so the industry standard has relaxed the acceptance criteria, allowing a certain degree of cracks in this area. At the same time, in order to reduce cracks, high-performance materials are generally used. However, if special high-performance materials are used throughout the circuit board structure, the manufacturing cost will increase significantly. Therefore, the current PCB board cannot solve the problem of hot zone cracks. Utility Model Content
[0005] The utility model aims to provide a structure for solving the cracks in the hot zone of PCB, which solves the problem that the hot zone cracks exist in the existing circuit board, which easily reduces the reliability of the circuit board and has high overall cost.
[0006] In order to solve the above technical problems, the utility model is realized by the following technical solutions:
[0007] The utility model discloses a structure for solving cracks in a hot zone of a PCB, comprising a PCB board body, wherein the PCB board body comprises a plurality of insulating dielectric layers, wherein the plurality of insulating dielectric layers are pressed together in sequence, wherein a layer plate assembly is arranged above the uppermost insulating dielectric layer, wherein the layer plate assembly comprises a first layer plate, a second layer plate, a high thermal conductivity semi-cured layer and a first FR4 semi-cured layer, wherein the high thermal conductivity semi-cured layer is arranged between the first layer plate and the second layer plate, wherein the first FR4 semi-cured layer is arranged between the second layer plate and the uppermost insulating dielectric layer, and wherein a layer plate assembly arranged in a mirror image is arranged below the lowermost insulating dielectric layer.
[0008] Preferably, the number of the first layer of laminates is greater than 1, and the high thermal conductivity semi-cured layer is arranged between two adjacent first layer laminates, and each high thermal conductivity semi-cured layer is composed of two high thermal conductivity semi-cured sheets pressed together.
[0009] Preferably, each FR4 prepreg layer is formed by laminating two FR4 prepreg sheets together.
[0010] Preferably, a copper layer is laminated on the upper and lower surfaces of each insulating dielectric layer, and the insulating dielectric layer and the upper and lower copper layers constitute a copper-clad laminate.
[0011] Preferably, the PCB board body is provided with laser blind holes, mechanical buried holes and mechanical through holes.
[0012] Preferably, a third FR4 semi-cured layer is laminated between two adjacent insulating dielectric layers.
[0013] Preferably, the FR4 prepreg layer three is formed by pressing two FR4 prepreg sheets together.
[0014] Preferably, the high thermal conductivity prepreg is a prepreg with a thermal conductivity greater than 1w / mk.
[0015] Preferably, the upper layer board assembly is formed by pressing the first layer board and the second layer board in sequence from top to bottom and pressing them on the top of the top insulating dielectric layer, and the lower layer board assembly is formed by pressing the first layer board and the second layer board in sequence from bottom to top and pressing them on the bottom of the bottom insulating dielectric layer.
[0016] Preferably, 1 / 3 to 3 ounces of copper foil is used on the PCB board body.
[0017] The utility model has the following beneficial effects:
[0018] 1. A special mixed-pressure laminate structure is adopted, which uses common FR4 semi-solid material and high thermal conductivity semi-solid layer 4. The main part uses conventional FR4 material, and only uses high thermal conductivity semi-solid sheet in key places where hot zone cracks are prone to occur. This not only solves the problem of hot zone cracks in circuit boards after being subjected to thermal stress, but also controls the manufacturing cost well; this structure has very good economic benefits;
[0019] 2. It can effectively solve the hot zone crack problem in conventional circuit boards and enhance the reliability of circuit boards.
[0020] 3. Moreover, the overall cost of the stacked structure of this structure is lower than the cost of using all high thermal conductivity materials, so it has more competitive advantages. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 This is a schematic diagram of the overall structure of a structure for solving cracks in a hot zone of a PCB in Example 1;
[0022] Figure 2 This is a schematic diagram of the decomposed structure of each layer of a structure for solving PCB hot zone cracks in Example 1;
[0023] Figure 3 This is a schematic diagram of the pressing structure of a structure for solving cracks in a hot zone of a PCB in Example 2 when no laser blind vias, mechanical buried vias, or mechanical through holes are provided.
[0024] Reference numerals:
[0025] Insulating dielectric layer 1, first layer board 2, second layer board 3, high thermal conductivity semi-cured layer 4, FR4 semi-cured layer one 5, layer board assembly 6, high thermal conductivity semi-cured sheet 401, FR4 semi-cured sheet 501, copper layer 8, laser blind hole 9, mechanical buried hole 10, mechanical through hole 11, FR4 semi-cured layer three 12. DETAILED DESCRIPTION
[0026] In order to make the purpose, technical solution and advantages of the embodiments of the utility model clearer, the technical solution in the embodiments of the utility model will be clearly and completely described below in combination with the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0027] Example 1
[0028] See also Figure 1-Figure 2As shown, the present embodiment discloses a structure for solving the cracks in the hot zone of PCB, comprising a PCB body, the PCB body comprising a plurality of insulating dielectric layers 1, the plurality of insulating dielectric layers 1 being pressed together in sequence, a layer board assembly 6 being arranged above the top insulating dielectric layer 1, the layer board assembly 6 comprising a first layer board 2, a second layer board 3, a highly thermally conductive semi-cured layer 4 and a FR4 semi-cured layer 5, a highly thermally conductive semi-cured layer 4 being arranged between the first layer board 2 and the second layer board 3, a highly thermally conductive semi-cured layer 4 being arranged between the second layer board 3 and the top An FR4 semi-cured layer 5 is arranged between the upper insulating dielectric layers 1, and a mirror-image layer assembly 6 is arranged below the lowermost insulating dielectric layer 1. The upper layer assembly 6 is formed by pressing the first layer 2 and the second layer 3 from top to bottom in sequence and pressing them on the upper part of the uppermost insulating dielectric layer 1, and the lower layer assembly 6 is formed by pressing the first layer 2 and the second layer 3 from bottom to top in sequence and pressing them on the lower part of the lowermost insulating dielectric layer 1; 1 / 3 to 3 ounces of copper foil is used on the PCB board body.
[0029] Preferably, the number of the first layer of laminates 2 is greater than 1, and the high thermal conductivity semi-cured layer 4 is arranged between two adjacent first layer laminates 2, and each high thermal conductivity semi-cured layer 4 is composed of two high thermal conductivity semi-cured sheets 401 pressed together; each FR4 semi-cured layer 5 is composed of two FR4 semi-cured sheets 501 pressed together.
[0030] Preferably, a copper layer 8 is laminated on the upper and lower surfaces of each insulating dielectric layer 1, the insulating dielectric layer 1 and the upper and lower copper layers 8 constitute a copper clad board, the PCB board body is provided with laser blind holes 9, mechanical buried holes 10, and mechanical through holes 11, and a FR4 semi-cured layer three 12 is laminated between two adjacent insulating dielectric layers 1, the FR4 semi-cured layer three 12 is composed of two FR4 semi-cured sheets 501 laminated together, and the high thermal conductivity semi-cured sheet 401 adopts a semi-cured sheet with a thermal conductivity greater than 1w / mk.
[0031] In the present embodiment, the insulating dielectric layer 1 has 3 layers, the number of the first layer boards 2 is 2, and the number of the third layer boards 6 is 3. During processing, the core layer structure is pressed together for the first time, and the three insulating dielectric layers 1 are pressed together in sequence. During the pressing process, the FR4 semi-cured layer 3 12 is pressed between adjacent insulating dielectric layers 1. During the second pressing, the upper first layer board 2 and the second layer board 3 are pressed in sequence, and the high thermal conductivity semi-cured layer 4 is passed between the two adjacent first layer boards 2, and between the bottom first layer board 2 and the second layer board 3, and the second layer board 3 and the top insulating layer are connected. A FR4 semi-cured layer 5 is pressed between the dielectric layers 1. During the third pressing, since the lower layer board component 6 is mirror-set to the upper layer board component 6, the first layer board 2 and the second layer board 3 are pressed in sequence from bottom to top, and a high thermal conductivity semi-cured layer 4 is passed between two adjacent first layer boards 2, and between the top first layer board 2 and the second layer board 3, and a FR4 semi-cured layer 5 is pressed between the second layer board 3 and the bottom insulating dielectric layer 1; finally, a completed PCB board body is formed, and then laser blind holes 9, mechanical buried holes 10, and mechanical through holes 11 can be made on the PCB board body.
[0032] The overall processing process of this structure is consistent with that of conventional PCBs. During processing, the inner insulating dielectric layer 1 is completed first; then a semi-cured sheet with a thermal conductivity greater than 1w / mk is applied for pressing. In the later stage, all pressings with mechanical buried holes in the sub-board must be equipped with this high thermal conductivity semi-cured layer 4, and the others are all made of ordinary FR4 semi-solid materials. Compared with conventional circuit boards, which are generally single-material stacked structures, such as high-Tg FR4 materials, in application scenarios that require rapid heat dissipation, all thermal conductive materials are generally used in this conventional way. This structure has the following technical effects:
[0033] 1. A special mixed-pressure laminate structure is adopted, which uses common FR4 semi-solid material and high thermal conductivity semi-solid layer 4. The main part uses conventional FR4 material, and only uses high thermal conductivity semi-solid sheet in key places where hot zone cracks are prone to occur. This not only solves the problem of hot zone cracks in circuit boards after being subjected to thermal stress, but also controls the manufacturing cost well; this structure has very good economic benefits;
[0034] 2. It can effectively solve the hot zone crack problem in conventional circuit boards and enhance the reliability of circuit boards.
[0035] 3. Moreover, the overall cost of the stacked structure of this structure is lower than the cost of using all high thermal conductivity materials, so it has more competitive advantages.
[0036] Example 2
[0037] See also Figure 3As shown, the present embodiment discloses a structure for solving cracks in hot zones of PCBs. The insulating dielectric layer 1 described in the present embodiment has a total of 3 layers, and the number of the first layer boards 2 is 3. During processing, the core layer structure is pressed together for the first time, and the three insulating dielectric layers 1 are pressed together in sequence. During the pressing process, the FR4 semi-cured layer 3 12 is pressed between adjacent insulating dielectric layers 1. During the second pressing, the upper first layer board 2 and the second layer board 3 are pressed in sequence, and the high thermal conductivity semi-cured layer 4 is passed between the two adjacent first layer boards 2, and between the bottom first layer board 2 and the second layer board 3, and the FR4 semi-cured layer 1 5 is pressed between the second layer board 3 and the top insulating dielectric layer 1. Then, the lower layer board assembly 6 is pressed in a mirror image manner of the above method to finally form a completed PCB board body, and then laser blind holes 9, mechanical buried holes 10, and mechanical through holes 11 are made on the PCB board body. Therefore, in the specific implementation, the number of the insulating dielectric layers 1, the number of the second layer boards 3, and the number of the first layer boards 2 can be determined according to specific requirements.
[0038] The above are only preferred embodiments of the present invention and do not limit the present invention. Any modification to the technical solutions recorded in the aforementioned embodiments and any equivalent replacement of some of the technical features therein, any modification, equivalent replacement, and improvement made are all within the protection scope of the present invention.
Claims
1. A structure for solving cracks in hot zone of PCB, characterized by: The PCB body comprises a plurality of insulating dielectric layers (1), wherein the plurality of insulating dielectric layers (1) are pressed together in sequence, a layer board assembly (6) is arranged above the uppermost insulating dielectric layer (1), the layer board assembly (6) comprises a first layer board (2), a second layer board (3), a high thermal conductivity semi-cured layer (4) and a FR4 semi-cured layer (5), a high thermal conductivity semi-cured layer (4) is arranged between the first layer board (2) and the second layer board (3), a FR4 semi-cured layer (5) is arranged between the second layer board (3) and the uppermost insulating dielectric layer (1), and a layer board assembly (6) arranged in a mirror image is arranged below the lowermost insulating dielectric layer (1).
2. A structure for solving cracks in hot zone of PCB according to claim 1, characterized in that: The number of layers of the first layer of layers (2) is greater than 1, and the high thermal conductivity semi-cured layer (4) is provided between two adjacent first layer of layers (2), and each high thermal conductivity semi-cured layer (4) is formed by two high thermal conductivity semi-cured sheets (401) pressed together.
3. The structure for solving the cracks in the hot zone of PCB according to claim 2 is characterized in that: Each FR4 prepreg layer (5) is formed by pressing two FR4 prepreg sheets (501) together.
4. The structure for solving the cracks in the hot zone of PCB according to claim 3 is characterized in that: A copper layer (8) is laminated on the upper and lower surfaces of each insulating medium layer (1), and the insulating medium layer (1) and the upper and lower copper layers (8) form a copper-clad board.
5. The structure for solving the cracks in the hot zone of PCB according to claim 4 is characterized in that: The PCB board body is provided with laser blind holes (9), mechanical buried holes (10), and mechanical through holes (11).
6. The structure for solving the cracks in the hot zone of PCB according to claim 5, characterized in that: A FR4 semi-cured layer three (12) is laminated between two adjacent insulating dielectric layers (1).
7. The structure for solving the cracks in the hot zone of PCB according to claim 6, characterized in that: The FR4 semi-cured layer three (12) is formed by pressing two FR4 semi-cured sheets (501) together.
8. The structure for solving the cracks in the hot zone of PCB according to claim 2 is characterized in that: The high thermal conductivity prepreg (401) is a prepreg with a thermal conductivity greater than 1w / mk.
9. A structure for solving PCB hot zone cracks according to claim 1 or 2, characterized in that: The upper layer board assembly (6) is formed by pressing the first layer board (2) and the second layer board (3) in sequence from top to bottom and pressing them above the uppermost insulating medium layer (1), and the lower layer board assembly (6) is formed by pressing the first layer board (2) and the second layer board (3) in sequence from bottom to top and pressing them below the lowermost insulating medium layer (1).
10. The structure for solving the cracks in the hot zone of PCB according to claim 2, characterized in that: The PCB board body uses 1 / 3 to 3 ounces of copper foil.