With the vigorous development of today's electronics industry, the global PCB industry has been rapid development, China as a PCB production country, accounting for more than 40% of the world's output, but also has been rapid development. In particular, the emergence of High Density Interconnect Technology (HDI) has prompted all kinds of electronic devices to constantly innovate, especially the rapid upgrading of intelligent electronic devices in recent years. More and higher technical innovation requirements are put forward for printed circuit board products in terms of multi-function, high integration, thinner, lighter, smaller, etc., which promotes the development of circuit board products to the direction of thinner and thinner thickness, more and more layers, thinner and denser wiring, and can be interconnected at any layer. "Light, thin, short, small, high density, high difficulty" is the main development trend of PCB products.
In the manufacturing process of HDI circuit board, there are many defects and difficulties in the process, the most important of which is that the blind hole can not be traced, and the blind hole can not be transferred to form a line.
Aiming at the above problems, the invention provides a blind hole wiring method for HDI circuit board, which saves more than 20% of wiring space, improves wiring density, and realizes miniaturization and lightweight of electronic products. The technical scheme to achieve the above purpose is: a blind hole wiring method for HDI circuit board, including the following steps,
S01: Design circuit wiring diagram;
S02: a substrate for making HDI circuit board, which is provided with a plurality of blind holes;
S03: Fill the blind hole by electroplating;
S04: The circuit routing diagram is arranged on the substrate by using the line graphics and image transfer method;
S05: Etching a conductor line on the substrate according to the circuit routing diagram by using the etching method.
Further, the blind hole wiring method of the HDI circuit board also includes the following steps,
S06: pressing a multilayer substrate and adding an insulating dielectric layer between the substrate;
Wherein, the step S06 follows the step S05.
Further, the thickness and distribution of the insulating dielectric layer in the step S06 are uniform.
Further, the blind hole wiring method of the HDI circuit board also includes the following steps,
S07: Coating the outermost substrate with a conductor line insulation layer; Wherein, the step S07 follows the step S06.
Further, the thickness and distribution of the insulation layer in the step S07 is uniform.
Further, the blind hole wiring method of the HDI circuit board also includes the following steps,
S08: Test various performance of the conductor line, including line signal transmission stability, anti-noise ability; Wherein, the step S08 is completed in the last step.
Further, the thickness and distribution of the electroplating layer produced by electroplating method in the step S03 are uniform.
After adopting the invention, the wiring space can be saved by more than 20%, the wiring density can be increased, and the electronic products can be miniaturized and lightweight. The blind hole electroplating and filling are flat without dents, and the completed hyperfine conductor line is uniform without notch or bump, and the corresponding layer line is well connected, and the signal transmission is stable and the anti-noise performance is good.
The invention relates to a blind hole wiring method for an HDI circuit board. The HDI circuit board in the present embodiment is a single-layer board. The specific wiring method includes the following steps.
S01: Design circuit wiring diagram. In the specific implementation, first design the circuit wiring diagram through the blind hole, design the production plan according to the requirements of the layout circuit wiring diagram, and select and evaluate the materials used and pre-compensate the conductor thickness, width and insulation layer thickness during etching. Since the circuit routing diagram is set according to the needs of the product, there are no restrictions in this embodiment.
S02: substrate for making HDI circuit board, which is provided with a plurality of blind holes. When implemented, the location of the blind hole is set according to the requirements of the circuit. The design requirements of the blind hole meet the national standards, but also meet the design requirements. It includes the horizontal distance and longitudinal distance between the blind holes.
S03: Fill the blind hole by electroplating. In the specific implementation, the thickness and distribution of the electroplating layer formed by electroplating method in the step S03 are uniform, that is, the thickness and uniformity of the electroplating layer after the blind hole is filled should be maintained. Electroplating adopts independently reformed and upgraded VCP circuit production line with high depth capability. During electroplating, the electroplating solution exchange in the blind hole is faster, the copper ion concentration distribution in the electroplating solution is more uniform, and the electroplating efficiency is higher. At the same time, the special electroplating solution combined with the modified special electroplating production line can make the blind hole electroplating filling more flat. Among them, the mechanism of blind hole filling electroplating solution: the electroplating solution contains leveling agent, inhibitor and brightener, and the leveling agent controls the copper atom crystallization during electroplating, and does not disordered crystallization; Inhibitor: can greatly slow down the surface plating rate of the circuit board plating, and the hole plating rate is normal, so as to achieve the purpose of filling the hole.
S04: The circuit routing diagram is arranged on the substrate by using the line graphics image transfer method.
Specifically, the circuit routing diagram is transferred to the circuit board (substrate), two methods are provided in this embodiment, as follows.
1: a. The circuit board wiring diagram is transferred to the photographic plate through the light drawing machine. b. Press a photosensitive resin film on the circuit board (substrate). c. Fix the negative with the circuit wiring diagram to the substrate of the pressed sensitive film, and fix it through the preset fixation point. d. Put the substrate into the exposure concentration for ultraviolet exposure, the light-transmitting position of the photographic resin film is sensitized to curing, and the light-opaque position of the photographic film remains unchanged when the photographic film is not exposed. e. Remove the negative, put the substrate into the developer, and the unexposed part is developed away, exposing the copper layer under the sensitive film. The exposed resin film continues to adhere to the copper surface due to curing. f. Put the substrate into the etching solution, etch off the copper layer without resin film protection, and the part protected by resin film is retained to form the required line because it cannot contact the potion.
2: a. Press a layer of photosensitive resin film on the circuit board (substrate). b. Put the substrate into the LDI exposure concentration. The laser head in the exposure machine exposes the circuit wiring diagram on the sensitive film of the substrate like an inkjet printer, and the sensitive resin film at the exposure position is photosensitive and cured. c. Put the substrate into the developer, and the unexposed part is developed away, exposing the copper layer under the sensitive film. The exposed resin film continues to adhere to the copper surface due to curing. d. Put the substrate into the etching solution, etch off the copper layer without resin film protection, and the part protected by resin film is retained to form the required line because it cannot contact the potion.
S05: Etch a conductor line on the substrate according to the circuit wiring diagram by using the etching method, and coat the conductor line insulation layer on the substrate.
After all the steps are completed, the final inspection process needs to be carried out.
S08: Test various performance of the conductor line, including line signal transmission stability, anti-noise ability; Wherein, the step S08 is completed in the last step.
Embodiment 2, this embodiment differs from Embodiment 1 in that the HDI circuit board in this embodiment is a multilayer circuit board, therefore, the blind hole routing method of the HDI circuit board in this embodiment also includes the following steps.
The following steps are also included after step S05 of Embodiment 1.
S06: Press a multilayer substrate and add an insulating dielectric layer between the substrate. When implemented, the thickness and uniformity of the insulating medium layer are controlled, that is, the thickness and distribution of the insulating medium layer in the step S06 are uniform.
S07: Coat the outermost substrate with a conductor line insulation layer.
Wherein, the step S07 follows the step S06. The thickness and distribution of the insulation layer in the step S07 are uniform.
In the implementation of the above embodiments, the main investigation is whether the blind holes of each layer are filled with electroplating, the width and uniformity of the conductor line, and whether the blind holes are well connected to each layer, so as to comprehensively evaluate the feasibility and advantages of this process technology.
The above is only a better embodiment of the invention and is not intended to limit the invention, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the invention shall be included in the scope of protection of the invention.
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