CN103857197A - Circuit board and manufacturing method of circuit board - Google Patents

Abstract

A circuit board, which includes a base, a conductive pad, a dielectric layer and a conductive metal block, the conductive pad is formed on a surface of the base, the dielectric layer is pressed on the side of the base with the conductive pad, the dielectric The electrical layer has a first surface away from the substrate, and openings corresponding to the conductive pads are formed in the dielectric layer, the openings are stepped holes, and each opening includes a first hole segment and a second hole connected to each other Section, the first hole section is adjacent to the conductive pad, the second hole section is adjacent to the first surface, the aperture of the second hole section is larger than the aperture of the first hole section, and the conductive metal block is formed in the opening and completely fills the hole. Describe the opening. The invention also provides a manufacturing method of the circuit board.

Description

Circuit board and manufacturing method thereof

technical field

The invention relates to the technical field of circuit board production, in particular to a circuit board and a production method thereof.

Background technique

A circuit board that uses a flip-chip ball grid array (FCBGA) to package chips usually needs to make a plurality of conductive bump structures arranged in an array for carrying solder balls. The conductive bumps need to penetrate through the solder resist layer and be electrically connected to corresponding conductive lines. In the prior art, it is common to form corresponding openings in the solder resist layer on the conductive lines, then form an electroplating barrier layer on the solder resist layer, and form an electroplating barrier layer corresponding to the openings in the solder resist layer in the electroplating barrier layer. Since both the openings of the solder resist layer and the openings of the electroplating barrier layer need to be developed and communicated with each other, the corresponding openings of the electroplating barrier layer and the openings of the solder resist layer need to be aligned during the manufacturing process. Afterwards, conductive bumps are formed in the openings of the solder resist layer by means of electroless plating and then electroplating. Finally, the electroplating barrier layer is removed to obtain conductive bumps protruding from the solder resist layer. In the above manufacturing method, the opening of the solder resist layer needs to be made relatively large, so as to facilitate the alignment when developing and forming the opening of the electroplating barrier layer. Moreover, since the formed conductive bumps and the solder resist layer are in contact with each other, and the contact area is small, the conductive bumps and the solder resist layer are easily separated from each other, and the reliability of the obtained circuit board is poor. Moreover, such a manufacturing method determines that the distribution density of the manufactured conductive bump structures is relatively small, which is not conducive to the dense distribution of multiple conductive bump structures.

Contents of the invention

Therefore, it is necessary to provide a circuit board and a manufacturing method thereof, which can improve the reliability of the conductive metal block of the circuit board.

A method for manufacturing a circuit board, comprising the steps of: providing a circuit substrate, which includes a base and a conductive pad formed on one surface of the base; pressing a dielectric layer on the side of the circuit substrate with the conductive pad, the dielectric layer It has a first surface away from the base; a plurality of openings corresponding to the conductive pads are formed in the dielectric layer by using a laser, each of the openings is a stepped hole, and the openings include interconnected The first hole segment and the second hole segment, the first hole segment is adjacent to the conductive pad, the second hole segment is adjacent to the first surface, and the aperture of the second hole segment is larger than the aperture of the first hole segment; and in the opening Conductive metal blocks are formed in the holes, and each conductive metal block is electrically connected to a corresponding conductive pad.

A circuit board, which includes a base, a conductive pad, a dielectric layer and a conductive metal block, the conductive pad is formed on a surface of the base, the dielectric layer is pressed on the side of the base with the conductive pad, the dielectric The electrical layer has a first surface away from the substrate, and openings corresponding to the conductive pads are formed in the dielectric layer, the openings are stepped holes, and each opening includes a first hole segment and a second hole connected to each other segment, the first hole segment is adjacent to the conductive pad, the second hole segment is adjacent to the first surface, the aperture of the second hole segment is larger than the aperture of the first hole segment, and the conductive metal block is formed in the opening and completely fills the Describe the opening.

Compared with the prior art, in the circuit board and its manufacturing method provided by the technical solution, the conductive metal blocks are formed in the dielectric layer, and the openings in the dielectric layer for accommodating the conductive metal blocks are stepped holes. Compared with the prior art, forming an opening in the solder resist layer and then forming a metal bump protruding from the surface of the solder resist layer can increase the contact area between the conductive metal block and the dielectric layer. Compared with the solder mask layer, the bonding ability of the dielectric layer to the metal is better than that of the solder mask layer to the metal. Therefore, the reliability of the circuit board provided by the technical solution is better.

Description of drawings

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

FIG. 2 is a schematic cross-sectional view of one side of the circuit substrate in FIG. 1 after lamination of a dielectric layer.

FIG. 3 is a schematic cross-sectional view after openings are formed in the dielectric layer of FIG. 2 .

FIG. 4 is a schematic cross-sectional view of the surface of the dielectric layer and the inner wall of the opening in FIG. 3 after a metal seed layer is formed.

FIG. 5 is a schematic cross-sectional view after forming an electroplated metal material on the surface of the metal seed layer in FIG. 4 .

Fig. 6 is a schematic cross-sectional view of the circuit board provided by the technical solution.

FIG. 7 is a schematic cross-sectional view after forming a surface treatment layer on the surface of the conductive metal block of the circuit board in FIG. 6 .

Description of main component symbols

circuit board 110 base 111 conductive pad 112 Conductive circuit layer 113 Dielectric layer 120 opening 121 first hole section 1211 Second Hole Section 1212 connection surface 1213 first surface 122 metal seed layer 130 Electroplated metal material 140 conductive metal block 150 end face 151 Connection 152 Loading part 153 surface treatment layer 160

The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings.

Detailed ways

The circuit board manufacturing method provided by the technical solution includes the following steps:

The first step, please refer to FIG. 1 , is to provide a circuit substrate 110 .

The circuit substrate 110 includes a base 111 and a plurality of conductive pads 112 .

The circuit substrate 110 may be a single-layer circuit substrate or a multi-layer circuit substrate. When the circuit substrate 110 is a single-layer circuit substrate, the base 111 is a single-layer dielectric layer. When the circuit substrate 110 is a multilayer circuit substrate, the base 111 may be a structure in which multiple layers of conductive circuits and multiple layers of dielectric layers are alternately stacked. A plurality of conductive pads 112 are in contact with a dielectric layer of the substrate 111 . In this embodiment, a conductive circuit layer 113 is formed on a surface of the base 111 , and the conductive circuit layer 113 includes a plurality of conductive pads 112 and a plurality of conductive circuits (not shown).

The second step, please refer to FIG. 2 , is to form a dielectric layer 120 on the surface of the plurality of conductive pads 112 of the circuit substrate 110 and the surface of the substrate 111 exposed from the conductive circuit layer 113 .

In this step, the dielectric layer 120 is formed on the surfaces of the plurality of conductive pads 112 and the base 111 exposed from the conductive pads 112 by pressing, so that the dielectric layer 120 completely covers the conductive circuit layer 113 . The dielectric layer 120 has a first surface 122 away from the substrate 111 .

The third step, referring to FIG. 3 , is to use a laser to form a plurality of openings 121 in the dielectric layer 120, each opening 121 corresponds to a conductive pad 112, and each conductive pad 112 is exposed from the corresponding opening 121 .

In this step, an excimer laser is used to form the opening 121 . The opening 121 is stepped. The opening 121 includes a first hole segment 1211 and a second hole segment 1212 that communicate with each other. The first hole segment 1211 is adjacent to the conductive pad 112 , and the second hole segment 1212 is close to the first surface 122 . Wherein, the diameter of the first hole section 1211 is smaller than the diameter of the second hole section 1212 . Preferably, the first hole segment 1211 and the second hole segment 1212 are arranged coaxially. Since the opening 121 is formed by laser, the longitudinal sections of the first hole section 1211 and the second hole section 1212 are both inverted trapezoidal. A connection surface 1213 is formed at the junction of the first hole section 1211 and the second hole section 1212 , the connection surface 1213 is exposed from the side of the second hole section 1212 , and the connection surface 1213 is substantially parallel to the first surface 122 .

Since the opening 121 is formed by an excimer laser, when the excimer laser is formed, the energy of the laser at different positions can be controlled, that is, it is located in the central area of the opening 121, and a larger energy is used to completely penetrate the dielectric layer 120. The first hole segment 1211 and the second hole segment 1212 are formed simultaneously. In the peripheral area surrounding the central area, a smaller laser energy is used, so that only part of the dielectric layer 120 is ablated and removed, and only the second hole segment 1212 is formed, thereby obtaining the stepped opening 121 .

In the fourth step, referring to FIGS. 4 to 6 , a conductive metal block 150 is formed in each opening 121 to obtain a circuit board 100 .

This step is specifically:

First, the metal seed layer 130 is formed on the inner wall of the opening 121 and the first surface 122 of the dielectric layer 120 .

The metal seed layer 130 can be formed by electroless metal plating. For example, it is formed by electroless copper plating. Of course, the metal seed layer 130 can also be formed in a black shadow, etc., so that the inner wall of the opening 121 and the surface of the dielectric layer 120 form the metal seed layer 130 .

Then, an electroplating metal material 140 is formed on the surface of the metal seed layer 130 by means of electroplating, so that the openings 121 are completely filled.

In this step, the metal material for electroplating may be copper, silver or the like. In this embodiment, the electroplated metal material 140 completely fills the opening 121 and is formed on the surface of the metal seed layer 130 on the first surface 122 of the dielectric layer 120 .

Finally, the electroplated metal material 140 and the metal seed layer 130 on the first surface 122 of the dielectric layer 120 are removed, and the electroplated metal material 140 and the metal seed layer 130 in the opening 121 form a conductive metal block 150 , thereby obtaining the circuit board 100 .

In this step, the electroplated metal material 140 and the metal seed layer 130 on the first surface 122 of the dielectric layer 120 may be removed by chemical etching. By controlling the etching time, the electroplated metal material 140 and the metal seed layer 130 in the opening 121 remain in the opening 121 to form the conductive metal block 150 . The conductive metal block 150 has an end surface 151 away from the conductive pad 112 . The end surface 151 is flush with the first surface 122 .

The conductive metal block 150 includes a connection portion 152 and a bearing portion 153 connected to each other. The connecting portion 152 is located in the first hole section 1211 , and the carrying portion 153 is located in the second hole section 1212 . The shape of the connecting portion 152 corresponds to the shape of the first hole segment 1211 , and the shape of the bearing portion 153 corresponds to the shape of the second hole segment 1212 . The connection portion 152 is electrically connected to the conductive pad 112 and the carrying portion 153 , and the carrying portion 153 is used for soldering with other components. Both the connecting portion 152 and the carrying portion 153 are rounded truncated, and the cross-sectional area of the connecting portion 152 is smaller than that of the carrying portion 153 .

Please refer to FIG. 7 , the circuit board manufacturing method provided by this technical solution may further include a step of forming a surface treatment layer 160 on the end surface 151 . The surface treatment layer 160 can be an organic solder protection layer, or a nickel-gold plating layer to protect the conductive metal block 150 .

Please refer to FIG. 6 and FIG. 7 , the technical solution also provides a circuit board 100 manufactured by the above method, and the circuit board 100 includes a base 111 , a conductive pad 112 , a dielectric layer 120 and a conductive metal block 150 .

The conductive pad 112 is formed on a surface of the base 111 . The dielectric layer 120 is pressed against the side of the substrate 111 having the conductive pad 112 . An opening 121 is formed in the dielectric layer 120, and the opening 121 is a stepped hole. The dielectric layer 120 has a first surface 122 away from the substrate 111 . The conductive metal block 150 is formed in the opening 121 and is electrically connected to the corresponding conductive pad 112 . The conductive metal block 150 has an end surface 151 away from the corresponding conductive pad 112 , and the end surface 151 is flush with the first surface 122 of the dielectric layer 120 .

The conductive metal block 150 includes a connection portion 152 and a bearing portion 153 connected to each other. The connecting portion 152 is located in the first hole section 1211 , and the carrying portion 153 is located in the second hole section 1212 . The shape of the connecting portion 152 corresponds to the shape of the first hole segment 1211 , and the shape of the bearing portion 153 corresponds to the shape of the second hole segment 1212 . The connection portion 152 is electrically connected to the conductive pad 112 and the carrying portion 153 , and the carrying portion 153 is used for soldering with other components. Both the connecting portion 152 and the carrying portion 153 are rounded truncated, and the cross-sectional area of the connecting portion 152 is smaller than that of the carrying portion 153 .

The conductive metal block 150 is composed of the metal seed layer 130 contacting the inner wall of the opening 121 and the electroplated metal material 140 formed on the surface of the metal seed layer 130 .

Further, a surface treatment layer 160 is formed on the end face 151 of each conductive metal block 150 to protect the conductive metal block 150 .

In the circuit board and its manufacturing method provided by this technical solution, the conductive metal block 150 is formed in the dielectric layer 120, and the opening 121 in the dielectric layer 120 for accommodating the conductive metal block 150 is a stepped hole. Compared with the prior art, forming an opening in the solder resist layer and then forming a metal bump protruding from the surface of the solder resist layer can increase the contact area between the conductive metal block 150 and the dielectric layer 120 . Compared with the solder mask layer, the bonding ability of the dielectric layer to the metal is better than that of the solder mask layer to the metal. Therefore, the reliability of the circuit board provided by the technical solution is better.

In addition, the openings in the dielectric layer are formed by laser ablation once, so that densely distributed openings can be formed, and relatively densely distributed conductive metal blocks can be formed to increase the wiring density of the circuit board.

It can be understood that those skilled in the art can make various other corresponding changes and modifications according to the technical concept of the present invention, and all these changes and modifications should belong to the protection scope of the claims of the present invention.

Claims (11)

1. a manufacture method for circuit board, comprises step:

Circuit substrate is provided, and it comprises substrate and is formed at the conductive pad on substrate one surface;

Dielectric layer is closed in one side pressure at described circuit substrate with conductive pad, and described dielectric layer has the first surface away from described substrate;

Adopt laser in dielectric layer, to form multiple and conductive pad multiple perforates one to one, each described perforate is shoulder hole, described perforate comprises interconnective the first hole section and the second hole section, the first hole section is adjacent with conductive pad, the second hole section is adjacent with first surface, and the aperture of the second hole section is greater than the aperture of the first hole section; And

In described perforate, form conducting metal piece, each conducting metal piece is electrically connected mutually with corresponding conductive pad.

2. the manufacture method of circuit board as claimed in claim 1, is characterized in that, each conducting metal piece has the end face away from corresponding conductive pad, and described end face is concordant with first surface.

3. the manufacture method of circuit board as claimed in claim 1, is characterized in that, forms conducting metal piece and comprise step in described perforate:

Form metal seed layer at the inwall of perforate and the first surface of dielectric layer;

By the mode of electroplating, form electroplating metal material on metal seed layer surface, described perforate is completely filled; And

Remove electroplating metal material and the metal seed layer of the first surface of dielectric layer, the electroplating metal material and the metal seed layer that are positioned at perforate form conducting metal piece.

4. the manufacture method of circuit board as claimed in claim 1, is characterized in that, adopts excimer laser to form described perforate.

5. the manufacture method of circuit board as claimed in claim 1, is characterized in that, described the first hole section and the second section junction, hole are formed with joint face, and described joint face exposes from the second hole section one side, and described joint face is parallel to first surface.

6. the manufacture method of circuit board as claimed in claim 1, it is characterized in that, described conducting metal piece comprises interconnective connecting portion and supporting part, described connecting portion be positioned at described the first hole section, described supporting part is positioned at the second hole section, described connecting portion is connected between corresponding conductive pad and supporting part, and the cross-sectional area of described connecting portion is less than the cross-sectional area of supporting part.

7. the manufacture method of circuit board as claimed in claim 1, is characterized in that, is also included in described end face and forms surface-treated layer.

8. a circuit board, it comprises substrate, conductive pad, dielectric layer and conducting metal piece, described conductive pad is formed at a surface of substrate, described dielectric layer is pressed on substrate and has a side of conductive pad, described dielectric layer has the first surface away from substrate, in dielectric layer, be formed with perforate corresponding to conductive pad, described perforate is shoulder hole, each described perforate comprises interconnective the first hole section and the second hole section, the first hole section is adjacent with conductive pad, the second hole section is adjacent with first surface, the aperture of the second hole section is greater than the aperture of the first hole section, conducting metal piece is formed in perforate, and fill described perforate completely.

9. circuit board as claimed in claim 8, it is characterized in that, described conducting metal piece comprises interconnective connecting portion and supporting part, described connecting portion be positioned at described the first hole section, described supporting part is positioned at the second hole section, described connecting portion is connected between corresponding conductive pad and supporting part, and the cross-sectional area of described connecting portion is less than the cross-sectional area of supporting part.

10. circuit board as claimed in claim 8, is characterized in that, each conducting metal piece has the end face away from corresponding conductive pad, and described end face is concordant with first surface.

11. circuit boards as claimed in claim 10, is characterized in that, described end face is formed with surface-treated layer.

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