A multilayer plate hole chain structure for HCT testing
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-28
- Publication Date
- 2026-08-11
AI Technical Summary
[0004]本实用新型的目的在于提供一种可提高FPC多层板HCT测试准确性和稳定性的多层板孔链结构，以解决现有孔链设计中热量聚集、产品形变、测试不准确等问题
[0014]采用上述结构后，本实用新型用于HCT测试的多层板孔链结构中，多组孔链单元均匀分布在多层板的四周及中部，形成非直线回路设计，有效地分散了测试过程中的热量，避免了基材的碳化，从而提升了测试的稳定性。多组孔链单元分布在多层板的四角及中部可以全面反映多层板在不同区域的层间连接性能，每一组孔链单元的外边缘与多层板的边缘间距≥9mm，可避免边缘效应影响测试结果。多层板顶层与底层的盲孔对称分布，减少了单面受热引发的产品形变，保证了测试结果的可靠性。此外，根据不同多层板类型的孔链单元参数（如通孔直径和盲孔规格）可以进行调整，使其适用于三层至六层等多种多层板，提高了兼容性。合理设计的CVL开窗及辅材避让，保证了测试点可以直接接触，避免了外部因素的干扰。这些设计共同工作，确保了HCT测试结果的准确性和测试过程的稳定性。针对镀铜后要做切片观察产品的镀铜效果时，有专门的孔链可以更好的测试产品，而且不用切板子上的产品，避免产品的浪费。
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Figure CN224618680U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of flexible circuit boards, and in particular to a multilayer board hole chain structure for high-temperature continuity testing (HCT, HotCopperTest), which is suitable for verifying the reliability, thermal stability and process compatibility of interlayer connections in multilayer FPC boards. Background Technology
[0002] In the manufacturing of multilayer flexible circuit boards, ensuring the reliability of interlayer connections is a key factor determining product quality. Existing HCT (Hole Thermal Cycling) testing technologies suffer from several design flaws in the via chain structure, limiting the accuracy and reliability of the tests. First, traditional via chains often employ a single linear loop design, leading to heat accumulation during testing and causing substrate carbonization, thus affecting the accuracy of the test results. Second, asymmetrical placement of blind or through vias on the top and bottom layers results in uneven heating on one side, potentially causing product deformation and further reducing test reliability. Furthermore, unreasonable via chain unit layouts, with some test structures too close to the board edge or covered by various auxiliary materials, fail to accurately reflect the actual performance of the product. These defects make existing via chain structures insufficient to meet the testing requirements of multilayer boards with different numbers of layers. Therefore, developing an optimized HCT via chain structure is crucial to address these technical problems.
[0003] In view of this, this utility model addresses the numerous shortcomings and inconveniences caused by the imperfect design of the hole chain structure of existing multilayer flexible circuit boards used for HCT testing. Through in-depth design and active research and development, this utility model was developed. Utility Model Content
[0004] The purpose of this invention is to provide a multilayer board hole chain structure that can improve the accuracy and stability of HCT testing of FPC multilayer boards, so as to solve the problems of heat accumulation, product deformation and inaccurate testing in existing hole chain designs.
[0005] To achieve the above objectives, the solution of this utility model is: A multilayer plate hole chain structure for HCT testing includes a multilayer plate with multiple sets of hole chain units evenly distributed around the perimeter and center of the multilayer plate. The distance between the outer edge of each hole chain unit and the edge of the multilayer plate is ≥9mm. Each hole chain unit has at least multiple through holes and multiple hole rings. The hole rings are located outside the through holes. The distance between adjacent through holes is equal in the X-axis and Y-axis directions. Each hole chain unit forms a non-linear loop.
[0006] Furthermore, the hole chain unit also includes blind holes, with blind holes symmetrically arranged on the top and bottom layers of the multilayer board, and through holes forming non-linear loops with each other or with blind holes.
[0007] Furthermore, the hole chain unit also includes a CVL window, which is located on the top layer of the multilayer board, and the size of the CVL window is larger than the size of the through hole.
[0008] Furthermore, the blind vias on the top and bottom layers of the multilayer board are not copper-plated, while the blind vias on the inner layers are covered with a continuous copper layer.
[0009] Furthermore, the through hole and the blind hole are connected to form a non-linear loop with a broken line angle of 90°-135°.
[0010] Furthermore, the diameter of the through hole is 0.9-2.0 mm, the minimum width of the hole ring is 0.1 mm, and the hole spacing between the through hole and the blind hole in the X-axis and Y-axis directions is 1.0 mm.
[0011] Furthermore, the perforated chain units are preferentially distributed in the upper and lower regions of the multilayer board. When the space in the upper and lower regions is insufficient, the perforated chain units are set inside the multilayer board, and the perforated chain units set inside the multilayer board are not covered by auxiliary materials.
[0012] Furthermore, the multilayer board is any one of three-layer double-sided blind hole board, four-layer double-sided blind hole board, five-layer double-sided board, or six-layer double-sided board.
[0013] Furthermore, the multilayer board is a six-layer board, which has outer blind holes arranged from the outside to the inside and inner blind holes arranged within the six-layer board.
[0014] With the above structure, the multilayer board hole chain structure for HCT testing in this invention features multiple sets of hole chain units evenly distributed around the perimeter and center of the multilayer board, forming a non-linear loop design. This effectively disperses heat during the testing process, avoids carbonization of the substrate, and thus improves test stability. The distribution of multiple sets of hole chain units at the four corners and center of the multilayer board comprehensively reflects the interlayer connectivity performance in different areas. The distance between the outer edge of each set of hole chain units and the edge of the multilayer board is ≥9mm, preventing edge effects from affecting test results. The symmetrical distribution of blind holes on the top and bottom layers of the multilayer board reduces product deformation caused by unilateral heating, ensuring the reliability of test results. Furthermore, the hole chain unit parameters (such as through-hole diameter and blind hole specifications) can be adjusted according to different multilayer board types, making it applicable to various multilayer boards from three to six layers, improving compatibility. The rationally designed CVL openings and auxiliary material avoidance ensure direct contact of test points, avoiding interference from external factors. These designs work together to ensure the accuracy of HCT test results and the stability of the testing process. When it's necessary to cross-section the product after copper plating to observe the plating effect, there are specialized hole chains that can better test the product without cutting the product on the board, thus avoiding product waste. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of a preferred embodiment of the present invention.
[0016] Figure 2 This is a schematic diagram of an embodiment of the hole chain unit of this utility model without blind holes.
[0017] Figure 3 This is a schematic diagram of an embodiment of the hole chain unit of this utility model that includes blind holes.
[0018] Figure 4 This is a schematic diagram of an embodiment of the three-layer double-sided blind hole plate of this utility model.
[0019] Figure 5 This is a schematic diagram of an embodiment of the four-layer double-sided blind hole plate of this utility model.
[0020] Figure 6 This is a schematic diagram of an embodiment of the five-layer double-sided blind hole plate of this utility model.
[0021] Figure 7 This is a schematic diagram of an embodiment of the present invention, which features a six-layer double-sided blind hole plus an inner blind hole. Detailed Implementation
[0022] To further explain the technical solution of this utility model, the following detailed description is provided through specific embodiments.
[0023] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.
[0024] like Figure 1 As shown, this utility model discloses a multilayer board via chain structure for HCT testing, including a multilayer board 1 with multiple circuit layers 11, wherein the multilayer board 1 is provided with multiple sets of via chain units 2, which are evenly distributed around the perimeter and center of the multilayer board 1, as shown. Figure 1In the illustrated embodiment, the perforated chain unit 2 comprises five groups, correspondingly distributed at the four corners and center of the multilayer board 1. This design comprehensively reflects the interlayer connection performance of the multilayer board 1 in different regions. The outer edge of each group of perforated chain units 2 is ≥9mm from the edge of the multilayer board 1, ensuring sufficient distance between the perforated chain unit 2 (test strip) and the clamping area. This prevents the clamping pressure from being directly transmitted to the test lines of the perforated chain unit 2, reducing the risk of mechanical damage and avoiding the influence of edge effects on the test results. The multiple groups of perforated chain units 2 are preferentially distributed in the upper and lower regions of the multilayer board 1. When the space in the upper and lower regions is insufficient, they can be set inside the multilayer board 1, but it must be ensured that they are not covered by auxiliary materials.
[0025] like Figures 2 to 7 As shown, each hole chain unit 2 has at least a plurality of through holes 21 and a plurality of hole rings 22. The hole rings 22 are disposed outside the through holes 21. The distance between adjacent through holes 21 in the X-axis and Y-axis directions is equal and is 1.0 mm. The through holes 21 of each hole chain unit 2 form a non-linear loop.
[0026] Figure 2 In the illustrated embodiment, the via chain unit 2 includes a through hole 21 and a via ring 22. The through hole 21 includes a basic through hole 211 and an interlayer through hole 212. The diameter of the basic through hole 211 is fixed at 0.9 mm and is used for basic continuity testing. The diameter of the interlayer through hole 212 is adjusted according to the thickness of the substrate stack to adapt to the interlayer continuity requirements of different layers. The minimum width of the via ring 22 is 0.1 mm, which is the distance between the hole wall and the outer copper ring to ensure the reliability of the connection between the hole copper and the outer copper foil.
[0027] like Figure 3 In the embodiment shown, the hole chain unit 2 includes a CVL window 23 and a blind hole 24 in addition to the through hole 21 and the hole ring 22. The CVL window 23 is located on the top layer of the multilayer board 1, and the size of the CVL window 23 is larger than the size of the through hole 21. The CVL window 23 is used to expose the test point and avoid the cover film from blocking the probe contact.
[0028] like Figures 3 to 7 In the illustrated embodiment, the blind vias 24 on the top and bottom layers of the multilayer board 1 are outer layer blind vias 241, and the blind vias disposed within the multilayer board 1 are inner layer blind vias 242. The outer layer blind vias 244 on the top and bottom layers are symmetrically arranged. The outer layer blind vias 241 have no copper plating, while the inner layer blind vias have a continuous copper layer. Figure 4 As shown, the multilayer board 1 is a three-layer double-sided blind hole board; as Figure 5 As shown, the multilayer board 1 is a four-layer double-sided blind hole board; as Figure 6 As shown, the multilayer board 1 is a five-layer double-sided blind hole board; as Figure 7 As shown, the multilayer board 1 is a six-layer double-sided board with an outer blind hole 241 and an inner blind hole 242.
[0029] like Figures 3 to 7 In the embodiment shown, the through hole 21 and the blind hole 24 are connected to form a non-linear loop with a zigzag angle of 90°-135°, which further disperses heat and prevents the substrate from carbonizing.
[0030] like Figure 3 As shown, the diameter of the through hole 21 of the hole chain unit 2 is 0.9-2.0mm, the minimum width of the hole ring 22 is 0.1mm, and the hole spacing D1 and D2 between the through hole 21 and the blind hole 24 in the X-axis and Y-axis directions are both 1.0mm, forming a non-linear loop, thereby controlling the hole density and avoiding heat accumulation.
[0031] The above embodiments and figures are not intended to limit the product form and style of this utility model. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of this utility model.
Claims
1. A multilayer plate hole chain structure for HCT testing, characterized in that: The system includes a multilayer board with multiple sets of hole chain units evenly distributed around the perimeter and center of the multilayer board. The distance between the outer edge of each hole chain unit and the edge of the multilayer board is ≥9mm. Each hole chain unit has at least multiple through holes and multiple hole rings. The hole rings are located outside the through holes. The distance between adjacent through holes is equal in the X-axis and Y-axis directions. Each hole chain unit forms a non-linear loop.
2. The multilayer plate hole chain structure for HCT testing as described in claim 1, characterized in that: The hole chain unit also includes blind holes. Blind holes are symmetrically arranged on the top and bottom layers of the multilayer board, and through holes form non-linear loops with each other or with blind holes.
3. The multilayer plate hole chain structure for HCT testing as described in claim 2, characterized in that: The hole chain unit also includes a CVL window, which is located on the top layer of the multilayer board and has a larger size than the through hole.
4. The multilayer plate hole chain structure for HCT testing as described in claim 2, characterized in that: The blind vias on the top and bottom layers of the multilayer board have no copper plating, while the blind vias on the inner layers have a continuous copper plating.
5. A multilayer plate hole chain structure for HCT testing as described in claim 1, characterized in that: The through holes and blind holes are connected to form a non-linear loop with a broken line angle of 90° - 135°.
6. The multilayer plate hole chain structure for HCT testing as described in claim 2, characterized in that: The diameter of the through hole is 0.9-2.0 mm, the minimum width of the hole ring is 0.1 mm, and the hole spacing between the through hole and the blind hole in the X-axis and Y-axis directions is 1.0 mm.
7. The multilayer plate hole chain structure for HCT testing as described in claim 1, characterized in that: The perforated chain units are preferentially distributed in the upper and lower regions of the multilayer board. When the space in the upper and lower regions is insufficient, the perforated chain units are set inside the multilayer board, and the perforated chain units set inside the multilayer board are not covered by auxiliary materials.
8. A multilayer plate hole chain structure for HCT testing as described in claim 2, characterized in that: The multilayer board is any one of three-layer double-sided blind hole board, four-layer double-sided blind hole board, five-layer double-sided board, or six-layer double-sided board.
9. A multilayer plate hole chain structure for HCT testing as described in claim 2, characterized in that: The multilayer board is a six-layer board, which has outer blind holes arranged from the outside to the inside and inner blind holes arranged within the six-layer board.