1. Field of the Invention
The present invention relates to a manufacturing method of a circuit board, and more particularly to a manufacturing method in which an electrode mold of a conductive circuit pattern is first made, then by electroplating, a conductive circuit metal layer is formed on the electrode mold, and then the conductive circuit metal layer is transferred to a dielectric layer.
2. Description of the Prior Art
The manufacturing techniques of circuit boards can be divided into additive and subtractive processes. The present developments of additive processes are mainly directed to approaches adopting printing electronic circuits directly on an insulating substrate with a functional ink. Unsolved issues of these approaches are being endeavored by many countries, but there is no known approach in production for the market. Subtractive processes, on the other hand, are currently the mainstream techniques that have matured from developments. One well known copper foil etching approach uses a board having a laminated copper foil as a substrate, forms anti-etching circuit patterns on the copper foil by means of screen printing or photo imaging, and removes the non-circuit portion by means of chemical etching to get the circuits. In order to obtain a basic circuit board, the process involves pre-processing the copper foil substrate, coating a light-sensitive material, exposing, developing, etching, and removing the coating, etc., and is therefore a complicated process undergoing high temperature, high humidity, strong acid and strong base treatments. The basic circuit board resulted from this method is shown in
A US patent application publication 20040168312 discloses a printed circuit board with inlaid outer layer circuit and the manufacturing method thereof. Primarily, it forms conductive circuits on a release mold board by means of metallization, light scribing or optical molding, and pattern electroplating, and transfers the circuit patterns to a dielectric layer by means of laminating. However, this manufacturing method requires for each circuit board repeating the foregoing metallization, light scribing or optical molding, and pattern electroplating processing steps to form a group of conductive circuits transferred to the dielectric layer, and is therefore complicated and costly.
A US patent application publication 20080098596 discloses a method for forming transcriptional circuits and a method for manufacturing a circuit board which involves forming an intaglio pattern corresponding to a circuit pattern on a mold board, filling the conductive pattern into the intaglio pattern, and by pressing a carrier onto the mold board transcribing the conductive material onto the mold board. However, during the step of pressing the carrier onto the mold board to transcribe the conductive material, the surface of the mold board is susceptible to be damaged from being in contact with the carrier, which may adversely impact the manufacture of the next conductive pattern. Therefore, the mold board reutilization for this manufacturing method is low.
In order to solve the foregoing problems, one objective of the present invention is to provide a manufacturing method of a circuit board which does not employ the traditional approaches performing image transferring, etching, laminating to the copper foil substrate; therefore, not only the product yield is raised, but also the cost is lowered, and the usage of water, electricity and various chemicals are reduced, thereby significantly reducing the harmful effects to the environment.
According to an embodiment, the manufacturing method of a circuit board includes the following steps. First, a first electrode mold is made, the upper surface thereof includes a first conductive circuit pattern and the first patterned groove, and the first patterned groove has a first dielectric layer disposed therein. Then the first electrode mold is electroplated so that a conductive circuit metal layer is formed on the first conductive circuit pattern. Thereafter, a dielectric layer is disposed on the first electrode mold, and the conductive circuit metal layer is transferred to at least a surface of the dielectric layer. Finally, the first electrode mold is separated from the dielectric layer, and the dielectric layer with the conductive circuit metal layer thereon constitutes a circuit board.
The objective, technologies, features and advantages of the present invention will become more apparent from the following description in conjunction with the accompanying drawings, wherein certain embodiments of the present invention are set forth by way of illustration and examples.
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a and
Next, a circuit pattern is transferred to the electrode mold material 20. By a black-line engraving method, the circuit pattern is engraved to the electrode mold material 20, as shown in
In a further step, a first insulating layer 26 is formed in the first patterned groove 22 to finish the process of making a first electrode mold 28. As illustrated in
Thereafter, the first electrode mold 28 is electroplated. The first conductive circuit pattern 24 would be attached with metal, thereby forming a conductive circuit metal layer 30. As shown in
Next, the first electrode mold 28 finished with electroplating for the conductive circuit metal layer 30 is taken out and a first dielectric layer 32 is disposed on the first electrode mold 28. As illustrated in
In a further step, the conductive circuit metal layer 30 of the first electrode mold 28 is embedded within the dielectric layer 32, as shown in
Finally, the first electrode mold 28 is separated from the dielectric layer 32, as shown in
Continuing the above description, since the electrode mold material 20 used has a lower bonding force with the electroplated metal, the conductive circuit metal layer 30 after electroplating can be easily and completely transferred to the dielectric layer 32. The number of metal layers electroplated, the kind, and the thickness can be decided in accordance with the subsequent need of the product. Also, to adapt to the usage environment of the product, the voltage and current for electroplating can be adjusted to control the grain and the surface roughness of the conductive circuit metal layer 30.
In another aspect, referring still to
In the manufacturing method of the circuit board of the present invention, there is no need to perform image transferring, etching and laminating, etc, on the copper foil substrate as in the traditional manufacturing process; instead, the circuit pattern is directly manufactured on the first electrode mold, through electroplating, the circuit pattern is metallized and a conductive circuit metal layer is formed, and through laminating, the conductive circuit metal layer is transferred and embedded into the dielectric layer. Compared to the traditional process, the present invention saves a lot of processing steps, significantly reducing the time required, enhancing the product yield, and conserving water, electricity and chemicals and is therefore of great help to cost reduction and environmental protection.
On the other hand, in the present invention, as shown in
Continuing the above description, when both sides of the circuit board have conductive circuit metal layers, conductive through holes are required for electrical connection.
In summary, the manufacturing method of the circuit board of the present invention has the following advantages:
1. the present invention provides a process free of many processing steps required in the traditional process, thereby enhancing product yield, lowering cost, decreasing the usage for water, electricity and chemicals, and significantly reducing the harmful impacts to the environment.
2. the conductive circuit metal layer is embedded into the dielectric layer: therefore, three of its surfaces are adhesively joined to the dielectric layer, effectively increasing the attaching strength.
3. stacking process is performed on the electrode mold: since the electrode mold is made of a material that is firm, less susceptible to deformation, and not easily expand or contract, misalignment issues during stacking for double layer or multi-layer circuit board are reduced.
4. overall thickness is more accurately controlled: since each layer is individually made from a conductive circuit metal layer and a dielectric layer, the overall thickness of the product can be definitely controlled.
5. the internal bubbles are reduced and the surface is flatter: because the conductive circuit metal layer is embedded in the dielectric layer, the height differences resulted from the topography of circuit distribution is reduced, which helps reducing the bubbles generated during the stacking at the inner layers, and ameliorating the printing quality of the solder-resistant green paint at the outer layer.
While the invention is susceptible to various modifications and alternative forms, a specific example thereof has been shown in the drawings and is herein described in detail. It should be understood, however, that the invention is not to be limited to the particular form disclosed, but to the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the appended claims.
Number | Date | Country | Kind |
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99133494 | Oct 2010 | TW | national |