TWM496319U - Printed circuit board - Google Patents

Abstract

The present disclosure provides a printed circuit board and an apparatus for fabricating printed circuit board. The printed circuit board includes a substrate having a upper surface; a first trench in the upper surface of the substrate; a first via formed in the first trench and penetrating through the substrate; and a first conductive layer disposed in the first trench and the first via, the first trench is electrically connect with the first via. An apparatus for fabricating the printed circuit board is also provided.

Description

A printed circuit board

The present invention relates to a printed circuit board and a printed circuit board manufacturing apparatus, and more particularly to a printed circuit board and a printed circuit board manufacturing apparatus which are manufactured by an ink jet method.

Printed circuit boards are an indispensable component of electronic products that connect electronic components together via circuits on a printed circuit board and perform their overall function. A conventional method of manufacturing a printed circuit board includes forming an insulating layer on a printed plating board substrate; forming a metal layer on the insulating layer, such as a copper foil or an aluminum foil; and partially shielding and unshielding according to the circuit design. Corroded to form a wire; if the printed circuit board is a multi-layer circuit board, then the layering is started; after the layering is completed, the multi-layer circuit board is holed and plated so that the different layers can conduct electricity to each other.

With the miniaturization of the control system, the amount of current required on the printed circuit board is also reduced. Today's printed circuit board applications are also turning to low-voltage and low-current applications, and the circuit on the board needs to be reformed. The thickness and width of the line must be reduced in response to this trend. The traditional screen printing and lithography are also unable to meet the precision problems. The subsequent printing and lithography cannot meet the development and application requirements of the next printed circuit board due to the precision problem. And the traditional method of manufacturing printed circuit boards also has serious pollution problems, and waste solution processing also costs.

Therefore, the present invention utilizes inkjet printing technology to perform a printed circuit board manufacturing method, which can greatly simplify the manufacturing process of the printed circuit board, can save many complicated processes, improve the process and cost efficiency, and reduce the manufacturing process. pollution problem. For example, in this process, the copper plating of the conventional process and the etching of the copper foil into the circuit are not required, and the pollution caused by the etching process is reduced. The formed printed circuit board also has fine line distribution and high precision. In the method, the energy beam is also used for groove etching and perforation, so that the circuit can be formed in the groove, and the printed circuit board manufactured by the method provided by the novel has a flat surface, which can reduce the printed circuit board. Thickness, this flat surface structure can facilitate the lamination of multilayer printed circuit boards and facilitate processing applications in a variety of electronics industries.

One aspect of the present invention is a printed circuit board, a substrate having an upper surface, a first recess recessed in the upper surface of the substrate, and a first through hole in the first recess, and a first conductive layer is disposed in the first recess and in the first through hole, and the first through hole is electrically connected to the first recess.

According to some embodiments of the present invention, the printed circuit board further includes a first insulating layer covering the first conductive layer in the first recess, and the first insulating layer does not cover the first through hole.

According to some embodiments of the present invention, the height of the first insulating layer is horizontal to the upper surface of the substrate. New type

According to some embodiments of the present invention, the printed circuit board further includes a second insulating layer covering the upper surface of the substrate and the first insulating layer; and a second recess formed in the second insulating layer An upper surface; a second via hole in the second recess and extending through the second insulating layer; a second conductive layer formed in the second recess and the second via; and a third insulating layer Covering the second conductive layer and filling the second recess, and the third insulating layer does not cover the second through hole.

According to some embodiments of the present invention, the material of the conductive layer is a conductive paste or a conductive powder.

According to some embodiments of the present invention, the materials of the first insulating layer, the second insulating layer and the third insulating layer are all resins.

Another aspect of the present invention is a printed circuit board manufacturing apparatus comprising a printed circuit board carrier; a printed circuit board drilling head disposed on the printed circuit board stage; and a conductive material nozzle disposed on the printing a circuit board stage; an insulating material nozzle disposed on the printed circuit board stage; a three-dimensional moving device coupled to the printed circuit board carrier; and an operating system associated with the nozzles The transmitting head and the three-dimensional mobile device are coupled.

According to some embodiments of the present invention, the three-dimensional moving device is used to move a printed circuit board carrier or a mobile printed circuit board drilling head, a conductive material nozzle, and an insulating material nozzle.

According to some embodiments of the present invention, wherein the conductive material nozzle The conductive material used is a conductive paste or a conductive powder.

According to some embodiments of the present invention, the conductive material used in the conductive material nozzle is selected from the group consisting of gold, aluminum, copper, indium, bismuth, magnesium, chromium, tin, nickel, silver, iron, titanium, alloys thereof, compounds thereof or Its combination.

According to some embodiments of the present invention, the insulating material used for the insulating material nozzle is a resin or a dielectric material.

According to some embodiments of the present invention, the printed circuit board drilling head is an energy beam emitting source.

100, 101‧‧‧ substrate

102, 103‧‧‧ upper surface

104, 105‧‧‧ lower surface

106, 107, 108‧‧‧ first groove

112, 113‧‧‧ first through hole

120, 121, 122‧‧‧ first conductive layer

130, 131, 132‧‧‧ first insulation

140, 150, 160‧‧‧second insulation

142, 152, 162‧‧‧ second groove

144, 154, 164‧‧‧ second conductive layer

146, 156, 166‧‧‧ third insulation layer

143, 153, 168‧‧‧ second through hole

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood. 2A to 2F are a top view and a cross-sectional view showing a manufacturing method of a printed circuit board according to an embodiment of the present invention; a new type and a third drawing show printing according to an embodiment of the present invention; Schematic diagram of the circuit board manufacturing device.

The spirit and scope of the present invention will be apparent from the following description of the preferred embodiments of the invention. It does not depart from the spirit and scope of the present invention. And for clear instructions See, many of the practical details will be explained in the following description. However, it should be understood by those skilled in the art that these practical details are not necessary in some embodiments of the present invention and therefore are not intended to limit the present invention. In addition, some of the conventional structures and elements are shown in the drawings in a simplified schematic manner in order to simplify the drawings.

Please refer to FIGS. 1A to 1F . FIGS. 1A to 1F are a top and cross-sectional views showing a method of manufacturing a printed circuit board according to an embodiment of the present invention. Referring to FIG. 1, FIG. 1 is a top view of a substrate 100 of a printed circuit board, and a cross-sectional view taken along line AA' in the upper view. The embodiments of the present invention will be more clearly understood from the comparison of the top view and the cross-section. The substrate 100 has an upper surface 102 and a lower surface 104. The substrate 100 can be a soft substrate or a hard substrate. The material of the substrate 100 includes cotton paper, phenolic cotton paper, epoxy resin, glass cloth, matte glass, polyester film, polyimide film, tantalum carbide, aluminum nitride. And other materials commonly used in printed circuit boards or combinations thereof.

Please refer to FIG. 1B . FIG. 1B is a top view and a cross-sectional view showing a method of manufacturing a printed circuit board according to an embodiment of the present invention. A first recess 106 is formed on the upper surface 102 of the substrate 100. The first recess 106 is formed by etching the upper surface 102 of the substrate 100 with an energy beam. In some embodiments, the energy beam is a laser. The portion of the substrate 100 that is etched by the energy beam is vaporized at a high temperature without waste generation and does not cause contamination in the process. The energy beam also has the advantage of being precisely controllable to form a first groove 106 of a particular width and thickness. The first recess 106 is a position set by the circuit in the printed circuit board and can be changed in shape according to the circuit design. There is a first groove 106 a first through hole 112. The first through hole 112 may be formed by reinforcing the energy beam energy in the first groove 106 through the substrate 100. The first through hole 112 may be located at an end of the first groove 106 or a suitable circuit design and penetrate the upper surface 102 and the lower surface 104 of the substrate 100. A circular groove may also be etched around the first through hole 112 to facilitate subsequent program operations.

Referring to FIG. 1C, FIG. 1C is a top view and a cross-sectional view showing a method of manufacturing a printed circuit board according to an embodiment of the present invention. As shown in the figure, a first conductive layer 120 is formed in the first recess 106 and the first through hole 112. The first conductive layer 120 is a circuit of a printed circuit board. The first conductive layer 120 is formed in the first recess 106 and the first through hole 112 by inkjet printing a conductive agent. The first conductive layer 120 can electrically connect the first recess 106 and the first through hole 112. The conductive agent and the material of the first conductive layer 120 may be a conductive paste or a conductive powder. The conductive material in the conductive paste or the conductive powder is not limited as long as it has conductivity. The material is a metal or a non-metal and its oxides, carbides, borides, nitrides or carbonitrides. Metal conductive particles are, for example, gold, aluminum, copper, indium, bismuth, magnesium, chromium, tin, nickel, silver, iron, titanium, and alloys thereof, and oxides, carbides, borides, nitrides, and carbonitrides thereof. Particles. Non-metals such as carbonaceous particles include natural graphite flakes, expanded graphite, graphene, carbon black, nanocarbon, and carbon nanotubes. In some embodiments, the first conductive layer 120 is lower than the upper surface 102 of the substrate 100. In some embodiments, the first conductive layer 120 does not fill the first via 112. The first conductive layer 120 located in the first through hole 112 can ensure that the electronic component can be electrically connected when inserted into the first through hole 112 of the printed circuit board. If the hole size is not uniform, the step of reinforcing the electric connection such as electroplating may be performed again.

Please refer to FIG. 1D. FIG. 1D is a top view and a cross-sectional view showing a method of manufacturing a printed circuit board according to an embodiment of the present invention. As shown in the figure, a first insulating layer 130 is formed on the first conductive layer 120 in the first recess 106 and fills the first recess 106. The height of the first insulating layer 130 is horizontal to the upper surface 102 of the substrate to form a smooth printed circuit board surface. This design prevents the circuit and the insulating layer from protruding above the surface of the printed circuit board, and thus reduces the thickness of the printed circuit board. The printed circuit board of this horizontal surface is easy to stack to form a multilayer printed circuit board and facilitate subsequent electronic zeros. Component packaging. The first insulating layer 130 is used to protect the first conductive layer 120 so that the circuit of the printed circuit board is not in contact with the outside to avoid a short circuit. The first insulating layer 130 is formed in the first recess 106 by inkjet printing by spraying an insulating agent and overlying the first conductive layer 120. The material of the insulating agent includes an insulating material commonly used for printed circuit boards such as a resin or a dielectric material. The first insulating layer 130 is not formed on the first conductive layer 120 in the first via hole 112 to avoid hindering the electrical connection effect of the subsequent electronic components. In some embodiments, the surrounding grooves of the first through holes 112 are not sprayed with an insulating agent, which facilitates subsequent processing of solder, solder paste or electronic component assembly, and reduces the risk of the insulating agent falling into the through holes. . The printed circuit board manufacturing method uses energy beam etching and inkjet printing to manufacture a printed circuit board, which has good controllability and process convenience, eliminates complicated photoresist etching process, and greatly reduces process cost and pollution. And can carry out higher precision circuit design. The printed circuit board itself has the characteristics that the circuit is buried in the substrate. The first conductive layer 120 is formed in the first recess 106 and covered with the first insulating layer 130 by etching the first recess 106 in the substrate 100, so that the printed circuit board has a smooth surface, which can be applied to each Subsequent processing and processing, such as the touch screen of a tablet or a mobile phone, can also reduce the display area occupied by the screen frame to cover the wire. The first via hole 112 also has a first conductive layer 120, which can enhance the effect of the electrical connection without further steps to strengthen the conductive.

Please refer to FIG. 1E. FIG. 1E is a schematic cross-sectional view showing a method of manufacturing a printed circuit board according to an embodiment of the present invention. As shown in the figure, the printed circuit board in FIG. 1D can be flipped again to perform the steps of FIGS. 1B to 1D, including energy beam etching, conductive layer printing, and insulating layer printing to form a double-sided printed circuit. board. The printed circuit board shown in Fig. 1E is a double-sided printed circuit board, and the upper surface 102 and the lower surface 104 of the substrate 100 are formed with printed circuits. And the circuit is composed of the first conductive layer 120 and is covered by the first insulating layer 130 in the first groove 106. The first through hole 112 is electrically connected to the first conductive layer of the upper surface 102 and the lower surface 104. The two-sided circuit of the printed circuit board can be designed according to requirements.

Please refer to FIG. 1F. FIG. 1F is a schematic cross-sectional view showing a method of manufacturing a printed circuit board according to an embodiment of the present invention. The structure of the multilayer printed circuit board is illustrated in this figure. The multilayer printed circuit board may be formed by laminating a single-sided single-layer printed circuit board as in the embodiment of Fig. 1D or a double-sided single-layer printed circuit board as in the embodiment of Fig. 1F. The circuit of the printed circuit board can be designed according to the requirements, but the circuit is still buried in the printed circuit board, the surface of the printed circuit board is a flat surface, and there is no surface wire interference, which is favorable for forming a multi-layer printing Brush the board. In the embodiment of the figures, the two single-layer double-sided printed circuit boards are pressed together to form a two-layer printed circuit board. A printed circuit board is stacked on the printed circuit board in the embodiment of Figure 1E. The lower surface 105 of the substrate 101 is in contact with the upper surface 102 of the substrate 100. The upper surface 103 and the lower surface 105 of the substrate 101 have different circuit distributions. A first recess 107 is etched from the upper surface 103 of the substrate 101 by an energy beam, and the first conductive layer 121 is formed in the first recess 107 and covered by the first insulating layer 131. The lower surface 105 of the substrate 101 is etched out of the first recess 108 by an energy beam, and the first conductive layer 122 is formed in the first recess 108 and covered by the first insulating layer 132. And the upper surfaces 103, 105 above the printed circuit board are flat surfaces. The first through hole 113 penetrates the substrate 101 and is covered with the first conductive layer 121 to be electrically connected to the electronic component that is subsequently formed. In some embodiments, the laminated multilayer printed circuit board may be subjected to energy beam etching to form a through hole through the multilayer printed circuit board; or through the through holes 112, 113 in each layer of the printed circuit board may be connected as a through hole. In some embodiments, there is an adhesive layer between the two printed circuit boards.

Referring to FIGS. 2A to 2F, FIGS. 2A to 2F are a top view and a cross-sectional view showing a method of manufacturing a printed circuit board according to an embodiment of the present invention. 2A to 2E continue the steps of FIG. 1D to form a printed circuit board structure on a single-layer printed circuit board structure, and a flat printed circuit board can also be formed. The 2F plan is another embodiment of the same embodiment. Referring to FIG. 2A, a second insulating layer 140 is formed on the upper surface 102 of the substrate 100 and the first insulating layer 130 to cover the entire substrate 100. The second insulating layer 140 is formed by spraying an insulating agent on the upper surface 102 of the substrate 100 by inkjet printing. In some embodiments, the material of the insulating agent The material is a resin. The second insulating layer 140 is used as another substrate to form another layer of circuitry in the second insulating layer 140, and the circuit in the second insulating layer 140 does not cause the substrate 100 by the barrier of the second insulating layer 140. The first conductive layer 120 is short-circuited.

Referring to FIG. 2B, a second recess 142 is formed in the second insulating layer 140. The second recess 142 is formed by energy beam etching so that a circuit can be formed in the second recess 142. In some embodiments, a second via hole 143 may also be formed in the second recess 142. The second via hole 143 is also formed by energy beam etching. In some embodiments, The two through holes 143 can be opposite to and electrically connected to the first through holes 112. The distribution of the second grooves 142 and the second through holes 143 can be designed according to circuit requirements.

Referring to FIG. 2C, a second conductive layer 144 is formed in the second recess 142. The second conductive layer 144 is formed in the second recess 142 by inkjet printing a conductive agent. In some embodiments, the second via 143 of the second recess 142 also has a second conductive layer 144 that can be electrically connected to a portion of the first conductive layer 120 of the substrate 100. And the surface of the second conductive layer 144 does not protrude beyond the second groove 142.

Referring to FIG. 2D, a third insulating layer 146 is formed over the second conductive layer 144 and fills the second recess 142. The third insulating layer 146 serves to protect the second conductive layer 144 and restore the surface of the second insulating layer 140 to a flat surface. The third insulating layer 146 is formed by spraying an insulating agent into the second recess 142 by inkjet printing. And forming a printed circuit board with a double layer circuit. In some embodiments, the third insulating layer 146 is not formed on the second conductive layer 144 around the second via hole 143 to avoid causing the conductivity of the second via hole. good.

Please refer to FIG. 2E. FIG. 2E is a schematic diagram of a printed circuit board having a three-layer circuit. Repeating the steps in Figures 2A through 2D can form another layer of circuitry on the original printed circuit board. As shown in the figure, another second insulating layer 150 is formed on the second insulating layer 140; another second recess 152 is formed in the second insulating layer 150, and another second via 153 is formed. In the second recess 152; another second conductive layer 154 is formed in the second recess 152; and another third insulating layer 156 covers a portion of the second conductive layer 152. The second insulating layer 150, the second conductive layer 154 and the third insulating layer 156 are all formed by inkjet printing, and the second recess 152 and the second through hole 153 are formed by energy beam etching. The materials of the conductive layer and the insulating layer are the same as those of the above embodiment.

Please refer to FIG. 2F. FIG. 2F is a diagram showing a double-sided multilayer circuit board formed by reversing the structure of the printed circuit board shown in FIG. 2D and performing the steps of FIGS. 2A to 2D. A printed circuit is formed on both the upper surface and the lower surface of the substrate 100. And the circuit is composed of the first conductive layer 120 and is covered by the first insulating layer 130 in the first recess. The second insulating layer 140 covers the lower surface of the substrate 100. The second insulating layer 140 has a second recess 142 and a second through hole 143 therein. The second conductive layer 144 and the third insulating layer 146 are formed in the second recess 142 and are not protruded from the surface of the second insulating layer 140. In still another embodiment, the third insulating layer 146 does not cover the second conductive layer 144 surrounding the second via 143. A second insulating layer 160 covers the upper surface of the substrate 100. The second recess 162 and the second via 168 therein are also formed by energy beam etching. The second conductive layer 164 is sprayed on the second recess 162 and The second via hole 168 is electrically connected to the first conductive layer 120. A third insulating layer 166 is sprayed into the second recess 162, but is not sprayed on the second through hole 168 and its surroundings. This structure can form a multilayer circuit on a two-layer circuit board and still have a smooth surface. Moreover, since the thickness of the second insulating layer is thinner than the substrate, a thin printed circuit board having a multilayer wiring can also be formed. The position and number of the second through holes 168 may vary depending on the circuit design, or may be located in the middle of the second recess 162 or not aligned with the first through holes 112. The printed circuit board structures can also be stacked and pressed to form more layers of printed circuit boards.

According to the method for preparing a printed circuit board by energy beam etching and ink jet printing, a printed circuit board having a multilayer circuit can be formed by the steps in FIGS. 2A to 2F. Moreover, the printed circuit boards of the embodiments in the 2D to 2F drawings can be stacked on each other to form a multilayer printed circuit board. Moreover, the printed circuit boards of the present embodiment all have a flat surface, which facilitates subsequent processing or fabrication of a multilayer printed circuit board. Moreover, the manufacture of printed circuit boards does not require the use of conventional photoresist and chemical etching processes, which greatly reduces the pollution generated during the manufacturing process, for example, avoids the contamination of the copper foil and the etching solution when the circuit is conventionally formed, and compared with the conventional process, It can greatly simplify the process of printed circuit boards, eliminating many complicated processes, improving process and cost-effectiveness. The precision of the prepared printed circuit board can be improved. Moreover, the printed circuit board of the printed circuit board is buried in the groove, and the groove is electrically connected to the through hole. The way of completing the circuit by inkjet printing ensures the stability of the circuit connection and is more suitable for assembling the electronic component. Electrical connection requirements on the board.

Please refer to FIG. 3 , which is a schematic diagram of a manufacturing apparatus for a printed circuit board according to an embodiment of the present invention. Printed circuit board manufacturing device package A printed circuit board stage 400, a three-dimensional moving device 410, a printed circuit board drilling head 420, a conductive material nozzle 430, an insulating material nozzle 440, and an operating system 450 are included. The printed circuit board stage 400 is used to carry the substrate of the printed circuit board, and the printed circuit board can be fabricated and processed on the printed circuit board stage 400. The printed circuit board stage 400 may be provided with a printed circuit board fixing and positioning device for fixing the substrate of the printed circuit board. In some embodiments, the stage 400 has an air extraction device that draws a vacuum between the substrate of the printed circuit board and the printed circuit board stage 400 to secure the printed circuit board. A printed circuit board drilling head 420, a conductive material showerhead 430, and an insulating material showerhead 440. It is disposed on the printed circuit board stage 400 for making a printed circuit board.

The printed circuit board drilling head 420 can be an energy beam emitting head for etching grooves and through holes on the printed circuit substrate to allow the circuit to be formed in the recess. In some embodiments, the energy beam emitting head is a laser emitting head. A conductive material showerhead 430 is used to inkjet print a conductive agent in or on the surface of the substrate to form an electrical circuit. The conductive agent includes a conductive paste and a conductive powder, and the conductive paste and the conductive powder contain a conductive material such as a metal or a non-metal and an oxide, a carbide, a boride, a nitride or a carbonitride or a combination thereof. Metal conductive materials are, for example, gold, aluminum, copper, indium, bismuth, magnesium, chromium, tin, nickel, silver, iron, titanium and alloys thereof, and oxides, carbides, borides, nitrides and carbonitrides thereof. Particles. Non-metals such as carbonaceous particles include natural graphite flakes, expanded graphite, graphene, carbon black, nanocarbon, and carbon nanotubes. Insulating material showerhead 440 is used to inkjet printing an insulating agent to form an insulating layer on the circuit to protect the circuit. The insulating material contained in the insulating agent is resin or Dielectric material. It is also possible to add conductive material nozzles or insulating material nozzles using different materials according to the operation requirements, so as to realize the application of automated operation for manufacturing printed circuit boards. The nozzles and the drill heads can be disposed on the printed circuit board above the stage by means of a robot arm or a three-dimensional moving device, etc., to facilitate the manufacture of the printed circuit board.

The three-dimensional moving device 410 is coupled to the printed circuit board stage 400, and is movable up and down (A direction), left and right (B direction), and front and rear (C direction). The combination of the three-dimensional mobile device may include directly bonding with the printed circuit board carrier, transporting the substrate of the printed circuit board, and moving the printed circuit board carrier and the substrate with the nozzles 430, 440 and the drill head 450 fixed. Performing a manufacturing step; or combining the nozzles 430, 440 and the drilling head 450, and disposing the nozzles 430, 440 and the drilling head 450 on the three-dimensional moving device, and when the printed circuit board is manufactured, the substrate of the printed circuit board is not moved. The three-dimensional mobile device moves the showerheads 430, 440 and the drill head 450 for the steps of manufacturing a printed circuit board. The three-dimensional mobile device may include a sliding table, a stepping motor, a timing pulley and the like for three-dimensional movement and is not limited to the mobile device and the moving manner as illustrated in the drawing, as long as three-dimensional operation can be performed to control the printing position. In the device. The operating system 450 is coupled to the three-dimensional mobile device 410 and the printed circuit board drill head 420, the conductive material showerhead 430, and the insulating material showerhead 440 to control such devices. In some embodiments, the operating system 450 includes a computer that can manipulate the three-dimensional mobile device 410 to a specific location via a computer to operate the printed circuit board drill head 420, the conductive material showerhead 430, or the insulating material showerhead 440, including the control drill, as desired. The depth of the hole, the amount of the conductive agent of the shower head, and the amount of ink discharged from the insulating agent, etc., to form the above embodiment Printed circuit board. The printed circuit board manufacturing apparatus incorporates etching and ink jet technology on the same printed circuit board manufacturing apparatus, so that the manufacturing method of the printed circuit board of the above embodiment can be carried out using a single apparatus. Provide a more convenient and fast process, and mass production of this printed circuit board. Compared with the traditional process, the device and the manufacturing method can greatly simplify the process of the printed circuit board, eliminating many complicated processes, improving the process and cost-effectiveness.

Although the present invention has been described above in terms of a preferred embodiment, it is not intended to limit the present invention, and it is to be understood that those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. The scope of the new protection is subject to the definition of the scope of the patent application.

100‧‧‧Substrate

102‧‧‧ upper surface

104‧‧‧lower surface

106‧‧‧First groove

112‧‧‧First through hole

120‧‧‧First conductive layer

130‧‧‧First insulation

Claims (6)

A printed circuit board comprising: a substrate having an upper surface; a first recess recessed in an upper surface of the substrate; a first through hole located in the first recess and extending through the substrate And a first conductive layer located in the first recess and in the first through hole, and the first through hole is electrically connected to the first recess. The printed circuit board of claim 1 further comprising a first insulating layer overlying the first conductive layer in the first recess, and the first insulating layer does not cover the first via. The printed circuit board of claim 2, wherein the first insulating layer has a height horizontal to an upper surface of the substrate. The printed circuit board of claim 2, further comprising: a second insulating layer covering the upper surface of the substrate and the first insulating layer; a second recess formed in the second insulating layer An upper surface of the layer; a second through hole in the second recess and extending through the second insulating layer; a second conductive layer formed in the second recess and in the second through hole; as well as a third insulating layer covers the second conductive layer and fills the second recess, and the third insulating layer does not cover the second through hole. The printed circuit board of claim 1, wherein the conductive layer is made of a conductive paste or a conductive powder. The printed circuit board of claim 4, wherein the materials of the first insulating layer, the second insulating layer and the third insulating layer are all resins.