Small-spacing lamp bead circuit board
By using vacuum resin plugging and full-board electroplating processes to replace blind vias in small-pitch LED light boards, the problems of low alignment accuracy and filling efficiency of blind vias have been solved, enabling low-cost, high-yield manufacturing of multilayer circuit boards and improving conductivity alignment and surface flatness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANG XI XU SHENG DIAN ZI GU FEN YOU XIAN GONG SI
- Filing Date
- 2025-05-13
- Publication Date
- 2026-05-08
AI Technical Summary
The existing manufacturing process for small-pitch LED light boards suffers from problems such as high requirements for blind hole alignment accuracy, low hole filling efficiency, high equipment and chemical costs, and complex processes, resulting in low yield and high cost.
By using through holes instead of blind holes, and through vacuum resin plugging and full-board electroplating processes, combined with mechanical drilling, copper plating, ceramic grinding, and secondary electroplating, a multi-layer circuit board is formed, achieving connectivity of inner layer circuits and flatness of outer layer circuits, eliminating the need for laser drilling and reducing equipment and chemical costs.
It improves the alignment accuracy and surface flatness of PAD and hole, reduces the risk of poor soldering, increases yield, meets the conductivity alignment requirements, reduces equipment and chemical costs, and extends the lamp bead spacing to P1.0.
Smart Images
Figure CN224218574U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of circuit board technology, specifically to a small-pitch LED bead circuit board. Background Technology
[0002] Traditional manufacturing processes for small-pitch LED light boards employ the HDI (High-Intensity Distributed) process, which involves lamination → browning → laser blind via drilling → adhesive removal (or plasma) → copper plating → via filling → outer layer circuitry. Blind via alignment requires extremely high precision (a 1.25mm pitch requires a hole position error of <10µm), while laser drilling easily leads to poor via shape. Due to limitations in blind via plating control and parameters, controlling the via filling efficiency is difficult, and via filling plating is prone to voids and depressions (generally <5µm), causing quality issues such as broken copper at the blind via corners and poor soldering, affecting product yield. Furthermore, the HDI process suffers from drawbacks such as the high cost of dedicated blind via plating solutions and the complexity of the traditional process requiring multiple lamination and laser drilling processes (e.g., a 6-layer board requires 2 laminations and 3 laser drilling processes).
[0003] Therefore, the purpose of this utility model is to provide a low-cost, high-yield small-pitch LED bead circuit board. Utility Model Content
[0004] The purpose of this invention is to provide a small-pitch LED circuit board with advantages such as low manufacturing cost and high yield.
[0005] The technical solution of this utility model is as follows:
[0006] A small-pitch LED bead circuit board includes a multilayer circuit board formed by laminating one or more core boards with completed inner layer circuitry, through-holes penetrating the multilayer circuit board, a first copper plating layer deposited on the wall of the through-holes, a via-filling resin filling the through-holes, a copper plating layer deposited on the surface of the via-filling resin, and a second copper plating layer deposited on the surface of the outer copper foil of the multilayer circuit board through a full-board electroplating process. The via-filling resin is flush with the surface of the outer copper foil of the multilayer circuit board. The outer copper foil of the multilayer circuit board and the second copper plating layer are combined to form the surface copper layer of the circuit board, and the surface copper layer is designed with outer layer circuitry.
[0007] Furthermore, the diameter of the through hole is 0.2-0.3 mm.
[0008] Furthermore, the thickness of the first copper plating layer on the wall of the through hole is ≥18µm.
[0009] Furthermore, the thickness of the copper plating layer is 0.3-0.5 μm.
[0010] Furthermore, the copper thickness on the pore-sealing resin is ≥12µm.
[0011] Furthermore, the spacing between the LED chips and PADs on the circuit board is P1.0 or P1.25.
[0012] Compared with the prior art, the small-pitch LED circuit board provided by this utility model has the following advantages:
[0013] I. The small-pitch LED bead circuit board provided by this utility model uses through holes to connect the inner circuit boards, which can improve the alignment accuracy between the PAD and the hole to within 20um. Because vacuum resin plugging is used, the void rate of the resin plugging hole is <0.1%, while the traditional blind hole filling process generally has a void rate of more than 0.5% and has depressions due to the electroplating filling solution and parameter control. After vacuum resin plugging of the through holes, the plugging resin is flush with the copper surface of the multilayer circuit board after lamination by a ceramic grinding plate, and the plugging efficiency can reach more than 98%. After baking, the depression is generally <2um, which can reduce the risk of cold solder joints when soldering components. Therefore, the small-pitch LED bead circuit board provided by this utility model can significantly improve the alignment accuracy between the PAD and the hole and the flatness of the PAD surface, and reduce downstream soldering defects and other quality problems.
[0014] II. The small-pitch LED circuit board provided by this utility model uses through holes to connect the inner circuit boards. Compared with the prior art, it eliminates the need for laser drilling of blind holes and reduces equipment costs. At the same time, through-hole electroplating can save chemical costs compared with blind hole electroplating in the prior art.
[0015] III. The small-pitch LED circuit board provided by this utility model, after testing, shows that the offset between the LED PAD and the hole position is <5µm, which meets the conductivity alignment requirements. The adhesion of the copper layer on the surface of the resin-filled hole area is ≥1.2N / mm, which meets industry requirements (ASTM D3359 standard). The small-pitch LED circuit board of this utility model can extend the LED pitch to P1.0. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a schematic diagram of one embodiment of the small-pitch LED circuit board of this utility model. Detailed Implementation
[0018] To enable those skilled in the art to better understand the technical solutions in the embodiments of this utility model, and to make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be further described below.
[0019] It should be noted that the descriptions of these embodiments are for the purpose of aiding understanding of the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0020] A method for manufacturing a small-pitch light panel includes the following steps:
[0021] Lamination: Laminating one or more core boards with completed inner layer circuitry together to obtain a multilayer circuit board;
[0022] Drilling: Mechanically drill through holes with a diameter of 0.2-0.3 mm;
[0023] Plating copper: The thickness of the copper plating layer on the hole wall is 0.3-0.5um;
[0024] Through-hole electroplating: Electroplating is performed on the surface of the copper-plated hole to form a first copper plating layer on the hole wall, the thickness of the first copper plating layer being ≥18um;
[0025] Vacuum resin plugging: Epoxy resin with a shrinkage rate of <0.5% is used to fill the through-holes and then cured; the resin material used includes the following components by weight percentage:
[0026] Epoxy resin 65-75%, silica powder 25-35%;
[0027] The particle size of the silica powder is 1-3 μm;
[0028] In the vacuum resin plugging process, the vacuum degree is -0.08 MPa, and the curing conditions are 140-160℃ for 55-65 minutes.
[0029] Ceramic grinding plate: An alumina ceramic grinding wheel is used to grind the plate, making the resin surface inside the holes flush with the outer copper foil surface of the multilayer circuit board, with a surface roughness Ra < 0.1 μm. Grinding process parameters include: pressure 5–8 N / cm. 2 Rotation speed 200-300 rpm, linear speed 1-2 m / min;
[0030] Secondary copper plating: Copper plating is performed on the surface of the via-filling resin to form a copper plating layer, which covers the resin material after vacuum resin via filling and ceramic grinding. The thickness of the copper plating layer is 0.3-0.5um.
[0031] Secondary electroplating: Full board electroplating, depositing a second copper plating layer on the outer copper foil surface of the multilayer circuit board, and meeting the requirement that the copper thickness on the resin is ≥12um;
[0032] Outer layer circuit fabrication: The outer copper foil of the multilayer circuit board is combined with the second copper plating layer to form the surface copper layer of the circuit board. The outer layer circuit is fabricated on the surface copper layer and exposed by LDI (alignment accuracy controlled at ±5um). After etching, the line width / line spacing is 50um / 50um (tolerance controlled at ±10%).
[0033] Taking a four-layer LED light board with a P1.25 aperture as an example, the small-pitch LED circuit board produced through the above process has the following structure: Figure 1 As shown. The small-pitch LED circuit board of this embodiment includes a multilayer circuit board 1 formed by lamination, a through hole 2 penetrating the multilayer circuit board 1, a first copper plating layer 3 deposited on the wall of the through hole, a via-filling resin 4 filling the through hole, a copper plating layer 5 deposited on the surface of the via-filling resin, and a second copper plating layer 6 deposited on the surface of the outer copper foil of the multilayer circuit board by a full-board electroplating process. The outer copper foil of the multilayer circuit board and the second copper plating layer are combined to form a surface copper layer 7, on which outer circuitry is designed.
[0034] In this embodiment, the multilayer circuit board 1 includes a core board 11, a first PP layer 12 and a second PP layer 13 stacked on both sides of the core board 11, a first copper foil 14 stacked on the surface of the first PP layer 12, and a second copper foil 15 stacked on the surface of the second PP layer 13. The inner core board circuitry of the multilayer circuit board 1 is completed before lamination. The core board 11 includes an epoxy resin material layer 111 filled inside, a first core board copper foil 112 and a second core board copper foil 113 stacked on both sides of the epoxy resin material layer 111, and circuit layers are designed on the first core board copper foil 112 and the second core board copper foil 113 respectively; the first copper foil 14 and the second copper foil 15 are the outer copper foils of the multilayer circuit board.
[0035] Correspondingly, the diameter of the through-hole 2 is 0.2-0.3 mm, and the thickness of the first copper plating layer 3 on the through-hole wall is ≥18 μm; the through-hole plugging resin has a smooth surface after passing through the ceramic grinding plate, and the through-hole plugging resin after grinding is flush with the surface of the outer copper foil of the multilayer circuit board (i.e., flush with the surfaces of the first copper foil 14 and the second copper foil 15 respectively); the thickness of the copper plating layer 5 is 0.3-0.5 μm, and the copper thickness on the through-hole plugging resin is ≥12 μm (the copper thickness on the through-hole plugging resin is the sum of the thickness of the copper plating layer and the thickness of the second copper plating layer at the corresponding position). In this embodiment, the copper thickness on the through-hole plugging resin is 20 μm.
[0036] Tests have shown that the small-pitch LED circuit board of this invention has an offset of less than 5µm between the LED PAD and the hole position, which meets the conductivity alignment requirements. The adhesion of the copper layer on the surface of the resin-filled hole area is ≥1.2N / mm, which meets the industry requirements (ASTM D3359 standard).
[0037] In addition to the embodiments described above, multilayer circuit boards can be formed by laminating multiple core boards as needed. Furthermore, the small-pitch LED chip circuit board of this invention allows the LED chip PAD spacing to be extended to P1.0.
[0038] The embodiments of this utility model have been described in detail above, but this utility model is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and spirit of this utility model still fall within the protection scope of this utility model.
Claims
1. A small-pitch LED bead circuit board, characterized in that, The circuit board includes a multilayer circuit board formed by laminating one or more core boards with completed inner layer circuitry, through-holes penetrating the multilayer circuit board, a first copper plating layer deposited on the wall of the through-holes, a via-filling resin filling the through-holes, a copper plating layer deposited on the surface of the via-filling resin, and a second copper plating layer deposited on the surface of the outer copper foil of the multilayer circuit board through a full-board electroplating process. The via-filling resin is flush with the surface of the outer copper foil of the multilayer circuit board. The outer copper foil of the multilayer circuit board and the second copper plating layer are combined to form the surface copper layer of the circuit board, and the surface copper layer is designed with outer layer circuitry.
2. The small-pitch LED circuit board according to claim 1, characterized in that, The diameter of the through hole is 0.2-0.3 mm.
3. The small-pitch LED circuit board according to claim 2, characterized in that, The thickness of the first copper plating layer on the wall of the through hole is ≥18um.
4. The small-pitch LED circuit board according to claim 1, characterized in that, The thickness of the copper plating layer is 0.3-0.5 μm.
5. The small-pitch LED circuit board according to claim 1 or 4, characterized in that, The copper thickness on the pore-sealing resin is ≥12µm.
6. The small-pitch LED circuit board according to claim 1, characterized in that, The spacing between the LED chips and PADs on the circuit board is P1.0 or P1.25.