TWI536889B - Method for manufacturing the plugging through hole in printed circuit board and printed circuit board - Google Patents

Description

Circuit board plug hole manufacturing method and circuit board

The invention relates to a method for manufacturing a printed circuit board plug hole and a circuit board.

The ink plug hole means that a part of the conductive through hole is filled with ink to form a columnar plug hole ink during the manufacturing process of the printed circuit board (PCB), which can prevent the short circuit of the solder during soldering and prevent the conductive pass. Oxidation of the pores causes electrical defects.

At present, the PCB surface treatment ink plug hole is formed by printing the surface ink on both sides of the circuit board while inserting the ink into the conductive through hole to form the plug hole ink, and the end of the plug hole ink is not exposed during the exposure, after development, the plug hole One end of the ink is washed away by the developer, and the other end is not washed away. After curing the ink, a plugged circuit board is obtained. However, this method is liable to cause the ink to be excessively washed by the developer, and cannot meet the requirement that at least 50% to 90% of the ink in the plug hole is filled with the ink, and even there is no ink defect in the partial hole. In addition, the cross-section of the plug ink obtained after curing by this method is formed into a concave shape, which easily causes oxidation of the pore angle and the wall of the bare pore.

The invention provides a method for manufacturing a circuit board plug hole with better plug hole fullness and a circuit board.

A method for manufacturing a circuit board plug hole, comprising the steps of: providing a circuit substrate, wherein the circuit substrate comprises a first conductive circuit layer and a second conductive circuit layer on opposite sides; forming a plurality of electrical connections on the circuit substrate a conductive via layer and a conductive via of the second conductive trace layer, and a first via ring is formed on a surface of the first conductive trace layer at the open end of the conductive via; on a surface of the first conductive trace layer Forming a first ink layer and forming a plug ink in the plurality of conductive vias; providing a first backsheet, the first backsheet having a plurality of annular light-shielding regions corresponding to the first aperture ring, surrounded by each of the annular light-shielding regions The area is a central area, the central area is a light transmissive area, and the surface of the plug ink corresponding to the central area is exposed by exposing the first ink layer to the first ink layer and the plug ink Forming a central protective layer; developing the first ink layer and the plug ink to cause the first ink layer corresponding to the first hole ring to be developed and removed, so that the central protective layer Side etching is removed, and the plugging ink is developed into a convex outer shape; baking and curing the first ink layer and the plugging ink, forming a circuit board.

A circuit board comprising: a base layer, a first conductive circuit layer and a second conductive circuit layer formed on both sides of the base layer, a first ink layer formed on the first conductive circuit layer, and a first conductive layer formed on the second conductive circuit layer Two ink layers. The circuit board is further formed with a conductive via that electrically connects the first conductive circuit layer and the second conductive circuit layer, and the circuit board further includes a plug ink located in the conductive via, the plug The hole ink is located at one end of the first conductive circuit layer to have a convex shape.

Compared with the prior art, the present invention provides an optimized patterned negative film having a plurality of annular light-shielding regions corresponding to the plug holes, the central region of the annular light-shielding region being a head spot, during the exposure process, the central region The light-transmitting point is polymerized such that the photosensitive ink corresponding to the central portion of the plug hole forms a protective layer for blocking the developing developer, and the ink is not displayed by the developer during the developing process, so that The ink fullness in the plug hole is more than 80%.

FIG. 1 is a schematic cross-sectional view of a circuit substrate provided by the embodiment.

2 is a schematic cross-sectional view showing the formation of conductive vias on the circuit substrate of FIG. 1.

3 is a schematic cross-sectional view showing the formation of first and second ink layers on the surface of the circuit substrate of FIG. 2 and filling of the conductive via holes to form plug holes.

4 is a schematic cross-sectional view showing the first and second negative films respectively coated on the first and second ink layers of the circuit substrate of FIG.

FIG. 5 is a schematic cross-sectional view showing the first and second protective layers formed by polymerization of the first and second ink layers after exposure of the circuit substrate of FIG. 4. FIG.

6 is a schematic cross-sectional view showing a circuit board formed after the circuit substrate of FIG. 5 is developed.

Embodiments of the present invention provide a method for manufacturing a circuit board plug hole, including the steps of:

In the first step, referring to FIG. 1, a circuit substrate 110 is provided. The circuit substrate 110 includes a base layer 113 and first conductive circuit layers 101 and second conductive circuit layers 102 formed on opposite sides of the base layer 113.

The base layer 113 has an inner layer line 114 therein. The circuit substrate 110 includes opposing component faces 111 and solder faces 112. The component surface 111 is located on the side of the first conductive circuit layer 101 for placing electronic components; the solder surface 112 is located on the side of the second conductive circuit layer 102 for pins of the electronic component Provide solder joints. In other embodiments, the base layer 113 may also be a pure resin layer without the inner layer line 114.

In the second step, referring to FIG. 2, a plurality of conductive vias 115 are formed on the circuit substrate 110.

The conductive vias 115 are electrically connected to the first conductive circuit layer 101 and the second conductive circuit layer 102, respectively forming a first end at the open end of the conductive via 115 at the position of the element surface 111 and the solder surface 112. Hole ring 1110 and second hole ring 1120.

In this embodiment, first, a through hole is formed by mechanical drilling or laser etching, and then a continuous conductive layer is formed on the inner wall of the through hole, the element surface 111 of the open end of the through hole, and the solder surface 112, thereby The conductive via 115 and the first via 1110 and the second via 1120 are formed.

It can be understood that the formation of the conductive layer may adopt a plating through hole (PTH) process, a black hole process or a black shadow process.

In the third step, referring to FIG. 3, a first ink layer 121 and a second ink layer 122 are respectively formed on the element surface 111 and the solder surface 112, and the ink is filled with a plurality of conductive vias 115 to form a plug hole. Ink 117.

When the ink layer is formed, specifically, the ink is printed on the element surface 111 and the solder surface 112 by screen printing, and the ink is filled in the conductive via 115 by means of a continuous printing tape plug, thereby A first ink layer 121 and a second ink layer 122 are formed on the element surface 111 and the solder surface 112, respectively, and a cylindrical plug ink 117 is formed in the conductive via 115. In this embodiment, the ink is a photosensitive ink.

In this embodiment, the element surface 111 and the solder surface 112 are pretreated before forming the ink layer. Preferably, the volcanic sand is used to polish the circuit substrate for cleaning and roughening so that the ink that can be soldered in the subsequent process can be The circuit substrate has a better bonding force to prevent the ink from falling. Of course, if the processing of the circuit substrate 110 before the solder resist has made the surface of the circuit substrate 110 sufficiently clean and the copper surface is sufficiently rough, the pre-processing step can be omitted.

In addition, since the ink after printing is in a liquid state, it is not convenient for subsequent operations. Therefore, after printing, the ink layer should be pre-cured to make the ink surface layer solid in order to facilitate subsequent operations.

It can be understood that in addition to the screen printing ink used in the present invention, the ink can be sprayed by electrostatic spraying.

In the fourth step, referring to FIGS. 4-5, the first ink layer 121 is covered with a first negative film 131, the second ink layer 122 is covered with a second negative film 132, and the ink is exposed.

The first backsheet 131 has a plurality of annular light-shielding regions 130 corresponding to the first aperture ring 1110, and the outer ring diameter of the annular light-shielding region 130 is not less than the outer ring diameter of the first aperture ring 1110. A region surrounded by each of the annular light-shielding regions 130 on the first film 131 is defined as a central region 1300, and the central region 1300 is a light-transmitting region, and the diameter of the central region 1300 is smaller than the diameter of the plug ink 117. And the central region 1300 is aligned with the plug ink 117.

Of course, although not mentioned in the embodiment, the first backsheet 131 and the second backsheet 132 further have other light-shielding regions and light-transmissive regions to form a solder resist opening in a subsequent step to expose a portion of the film. The element surface 111 and the soldered surface 112 are described to mount the components.

Referring to FIG. 5, the exposure is performed such that the surface layer of the first ink layer 121 is polymerized to form the first protective layer 141, the surface layer of the second ink layer 122 is polymerized to form the second protective layer 142, and the center is The surface layer of the plug ink 117 corresponding to the region 1300 is polymerized to form a central protective layer 1410.

In this embodiment, the ink on the first ink layer 121 corresponding to the light-transmitting region of the first film 131 is irradiated by the ultraviolet light irradiation, and the ink corresponding to the light-transmitting region of the film is irradiated, and the ink is irradiated. A polymerization reaction occurs, a first protective layer 141 is formed on the surface layer of the first ink layer 121, and an ink corresponding to the central region 1300 of the first negative film 131 is polymerized, and the plug corresponding to the central region 1300 The surface layer of the hole ink 117 forms a central protective layer 1410, and the ink on the second ink layer 122 corresponding to the light-transmitting region of the second negative film 132 is irradiated to cause a polymerization reaction to form a second protection on the surface layer of the second ink layer 122. Layer 142.

In the fifth step, referring to FIG. 5 to FIG. 6, the first ink layer 121, the second ink layer 122, and the plug ink 117 are subjected to development processing.

The first ink layer 121 and the second ink layer 122 that are not covered by the first protective layer 141 and the second protective layer 142 are developed and removed, and the plug ink 117 is developed to form a convex shaped plug ink. 117. The plug ink 117 under the central protective layer 1410 is set to be the ink of the A zone, and the ink of the B zone is formed on both sides of the A zone. The principle of forming the plug ink of the convex shape is to control the development condition during the development process to make the ink of the surface of the B zone. It is developed, and, since the development of the zone A, the ink of the zone A is not developed under the barrier of the center protective layer 1410, but when the ink of the zone B is developed to be flush with the bottom surface of the center protective layer 1410 of the zone A, A The ink under the central protective layer 1410 of the region begins to undergo side etching, and at this time, the development continues, the side etching is enlarged, and the surface layer of the ink of the entire A region is developed, and the ink developed from the edge to the center of the plug ink 117. It is thinner and thinner, and finally the plug ink 117 having an outward convex shape is left. At this time, the center protective layer 1410 is also removed by the side etching, and the development is finished. That is, under the protection of the central protective layer 1410, the developer can only erode the ink on both sides of the central protective layer 1410 until the side etching occurs, and after the central protective layer 1410 is removed, the plug ink 117 is completely exposed. The development process will end. Due to the blocking effect of the central protective layer, the plug ink 117 is more than 80% full.

In the sixth step, the cured ink is baked to form a circuit board 100.

The ink on the circuit board 100 is completely polymerized and the solvent in the ink is sufficiently volatilized to form a layer of a solder resist ink which is strong and has good chemical resistance.

Referring to FIG. 6 , an embodiment of the present invention provides a circuit board 100 including a base layer 113 , a first conductive circuit layer 101 and a second conductive circuit layer 102 formed on two sides of the base layer 113 , and formed on the first conductive line. The first ink layer 121 of the layer 101 and the second ink layer 122 formed on the second conductive wiring layer 102. The circuit board 100 is further formed with a conductive via 115 electrically connected to the first conductive circuit layer 101 and the second conductive circuit layer 102. The circuit board 100 further includes a plug in the conductive via 115. The hole ink 117 is located at one end of the first conductive wiring layer 101 in a convex shape.

In summary, the present invention provides a method for fabricating a plug hole and a circuit board. The film used has a plurality of annular light-shielding regions 130 corresponding to the plug ink 117, and the central region 1300 surrounded by the annular light-shielding region 130 is a light-transmitting region. During the exposure process, the light-transmitting region of the central region 1300 is polymerized, so that the photosensitive ink corresponding to the surface layer of the central region 1300 in the plug ink 117 forms a central protective layer 1410 for blocking the developer. The fullness of the plug ink 117 is made 80% or more.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. However, the above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be covered by the following claims.

100‧‧‧ boards

110‧‧‧ circuit board

101‧‧‧First conductive circuit layer

102‧‧‧Second conductive circuit layer

111‧‧‧Component surface

1110‧‧‧First hole ring

112‧‧‧ solder joints

1120‧‧‧ second hole ring

113‧‧‧ basal layer

114‧‧‧ Inner line

115‧‧‧ conductive vias

117‧‧‧ hole ink

121‧‧‧First ink layer

122‧‧‧Second ink layer

130‧‧‧Circular shade

1300‧‧‧Central area

131‧‧‧ first negative

132‧‧‧Second negative

141‧‧‧First protective layer

1410‧‧‧ central protective layer

142‧‧‧Second protective layer

no

100‧‧‧ boards

111‧‧‧Component surface

112‧‧‧ solder joints

113‧‧‧ basal layer

101‧‧‧First conductive circuit layer

102‧‧‧Second conductive circuit layer

114‧‧‧ Inner line

115‧‧‧ conductive vias

117‧‧‧ hole ink

121‧‧‧First ink layer

122‧‧‧Second ink layer

Claims (8)

A method for manufacturing a circuit board plug hole, comprising the steps of:
Providing a circuit substrate, the circuit substrate including a first conductive circuit layer and a second conductive circuit layer opposite to each other;
Forming a plurality of conductive vias electrically connecting the first conductive circuit layer and the second conductive circuit layer on the circuit substrate, and forming a first surface on the first conductive circuit layer surface at the open end of the conductive via Hole ring
Forming a first ink layer on the surface of the first conductive circuit layer and forming a plug ink in the plurality of conductive via holes;
Providing a first negative film, the first negative film has a plurality of annular light-shielding regions corresponding to the first hole ring, and a region surrounded by each of the annular light-shielding regions is a central region, and the central region is a light-transmitting region, and passes through the first The negative film exposes the first ink layer and the plug ink, and forms a central protective layer on the surface layer of the plug ink corresponding to the central region;
Developing and processing the first ink layer and the plug ink, so that the first ink layer corresponding to the first hole ring is developed and removed, so that the central protective layer is removed by side etching, and The plug ink is developed into a convex shape; and the first ink layer and the plug ink are baked and cured to form a circuit board. The method for manufacturing a circuit board plug according to claim 1, wherein the circuit substrate comprises an opposite component surface and a solder surface, and the component surface is located on the side of the first conductive circuit layer for placing an electronic component; The solder surface is located on the side of the second conductive circuit layer for providing a solder joint for the pins of the electronic component. The method of manufacturing a circuit board plug according to claim 1, wherein the circuit substrate further comprises a base layer, and the first conductive circuit layer and the second conductive circuit layer are located on opposite sides of the base layer. The substrate layer has an inner layer line therein. The method for manufacturing a circuit board plug according to claim 1, wherein a first ink layer is formed on the surface of the first conductive circuit layer and a plug ink is formed in the plurality of conductive via holes by means of a plugging method. . The method for manufacturing a circuit board plug according to claim 1, wherein a diameter of the outer ring of the annular shading area is not smaller than a diameter of the outer ring of the first hole ring. The method of fabricating a circuit board plug according to claim 1, wherein the diameter of the central region is smaller than the diameter of the plug ink. The method for manufacturing a circuit board plug according to claim 1, wherein the method for manufacturing the circuit board plug hole further comprises the step of forming a second ink layer on the surface of the second conductive circuit layer. A circuit board comprising: a base layer, a first conductive circuit layer and a second conductive circuit layer formed on both sides of the base layer, a first ink layer formed on the first conductive circuit layer, and a first conductive layer formed on the second conductive circuit layer a second ink layer, the circuit board is further formed with a conductive via hole electrically connecting the first conductive circuit layer and the second conductive circuit layer, the circuit board further comprising a plug hole ink located in the conductive via hole The plug hole ink is located at one end of the first conductive circuit layer and has a convex shape.