TWI661751B - Printed circuit board and method for manufacturing the same - Google Patents

Abstract

The invention relates to a circuit board. The circuit board includes an insulating layer, a solder pad, and a nickel plating. Gold layer. The solder pad and the nickel-plated gold layer are both disposed on the insulating layer. The nickel-plated gold layer covers the solder pad. The solder pad includes a first conductive pad and a second conductive pad. The second conductive pad is disposed on the insulating layer. The first conductive pad is disposed on the second conductive pad. A thickness of the second conductive pad is smaller than a thickness of the first conductive pad. The second conductive pad has a protruding portion opposite to the first conductive pad. The protruding portion surrounds the first conductive pad. The invention also provides a method for manufacturing the circuit board.

Description

Circuit board and manufacturing method thereof

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

Printed circuit boards have been widely used for their advantages such as high assembly density. For the application of circuit boards, please refer to the literature Takahashi, A. Ooki, N. Nagai, A. Akahoshi, H. Mukoh, A. Wajima, M. Res. Lab, High density multilayer printed circuit board for HITAC M-880, IEEE Trans on Components, Packaging, and Manufacturing Technology, 1992, 15 (4): 1418-1425.

During the manufacturing process of the circuit board, the pads are usually surface-treated, and the surface of the pads is plated with a layer of nickel and a layer of gold. The solder pad, nickel plating layer, and gold plating layer are all disposed on the insulating layer, the nickel plating layer covers the solder pad, and the gold plating layer covers the nickel plating layer. In actual conditions, there are tiny voids at the junctions of the gold-plated layer, the nickel-plated layer, and the insulating layer. Humid air easily enters from the gap and metal corrosion occurs with the nickel plating layer. The nickel plating layer is corroded to a certain extent, and the gold plating layer will be peeled off from the circuit board.

In view of this, it is necessary to provide a circuit board and a manufacturing method thereof to solve the above technical problems.

A method for manufacturing a circuit board includes the steps of: providing a first copper foil layer and an insulating layer, the first copper foil layer being fixedly disposed on the insulating layer; and forming and forming a first copper foil layer surface A first conductive layer having a circuit pattern, the first conductive layer including a plurality of first conductive pads; etching the first copper foil layer to obtain a second conductive layer, and making the circuit pattern of the second conductive layer and the second conductive layer The circuit pattern of the first conductive layer corresponds directly. The second conductive layer includes a plurality of second conductive pads. The thickness of the second conductive pad is smaller than the thickness of the first conductive pad. The second conductive pads collectively constitute a soldering pad of the circuit board. Each first conductive pad is disposed on a corresponding second conductive pad, and the second conductive pad has a protruding portion relative to the first conductive pad. The protruding portion surrounds the first conductive pad; and a nickel-plated gold layer is plated on the upper surface and the side surface of the solder pad.

A circuit board includes an insulating layer, a solder pad, and a nickel-plated gold layer. The solder pad and the nickel-plated gold layer are both disposed on the insulating layer. The nickel-plated gold layer covers the solder pad. The solder pad includes a first conductive pad and a second conductive pad. The second conductive pad is disposed on the insulating layer. The first conductive pad is disposed on the second conductive pad. A thickness of the second conductive pad is smaller than a thickness of the first conductive pad. The second conductive pad has a protruding portion opposite to the first conductive pad. The protruding portion surrounds the first conductive pad.

Compared with the prior art, the circuit board and the manufacturing method thereof provided by the present invention include the solder pad, and the solder pad includes the second conductive pad and the first conductive pad. The second conductive pad is disposed on the insulating layer, the first conductive pad is disposed on the second conductive pad, and a thickness of the second conductive pad is smaller than a thickness of the first conductive pad. The two conductive pads have a protruding portion opposite to the first conductive pad, the protruding portion surrounds the first conductive pad, and the protruding portion is disposed close to the gold plating layer, replacing the nickel plating layer and the gold plating layer in preference. The air and moisture entering between the nickel-plated layer and the insulating layer react, delaying the reaction time of the nickel-plated layer and air and moisture, and to a certain extent, preventing the gold-plated layer from coming out of the circuit board Peel off.

100‧‧‧Circuit Board

10‧‧‧ Copper foil substrate

12‧‧‧ Insulation

14‧‧‧The first copper foil layer

20‧‧‧The first dry film

22‧‧‧The first dry film pattern

220‧‧‧ the first opening

30‧‧‧first conductive layer

32‧‧‧The first conductive pad

40‧‧‧Second dry film

42‧‧‧Second dry film pattern

420‧‧‧Second opening

50‧‧‧ second conductive layer

52‧‧‧Second conductive pad

54‧‧‧ prominence

60‧‧‧Line layer

70‧‧‧pad

80‧‧‧ nickel plating

90‧‧‧ gold plating

FIG. 1 is a schematic cross-sectional view of a copper foil substrate and a first dry film according to a preferred embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of the first dry film in FIG. 1 after being patterned.

FIG. 3 is a schematic cross-sectional view of the first dry film of FIG. 2 after development.

4 is a schematic cross-sectional view of the first dry film pattern after the first conductive layer is formed in FIG. 3.

5 is a schematic cross-sectional view of the copper foil substrate of FIG. 4 after the first dry film is removed.

6 is a schematic cross-sectional view of the first copper foil layer and the first conductive laminate of FIG. 5 after the second dry film is laminated.

FIG. 7 is a schematic cross-sectional view of the second dry film of FIG. 6 after exposure.

FIG. 8 is a schematic cross-sectional view of the second dry film of FIG. 7 after development.

FIG. 9 is a schematic cross-sectional view of the first copper foil layer in FIG. 8 after being patterned by etching.

FIG. 10 is a schematic cross-sectional view of the second dry film of FIG. 9 after being stripped from the first copper foil layer and the first conductive layer.

11 is a cross-sectional view of a nickel-plated layer and a gold-plated layer formed on the pad of FIG. 10.

In the following, a single-layer circuit board is taken as an example to describe a method for manufacturing the circuit board 100 provided in this technical solution. The method for manufacturing the circuit board 100 includes the following steps:

In the first step, referring to FIG. 1, a copper foil substrate 10 and a first dry film 20 are provided, and the first dry film 20 is adhered and fixed on the copper foil surface of the copper foil substrate 10.

The copper foil substrate 10 includes an insulating layer 12 and a first copper foil layer 14. The first copper foil layer 14 is covered on the insulating layer 12. The copper foil substrate 10 may be a flexible copper foil substrate or a rigid copper foil substrate. The first dry film 20 is coated on the first copper foil layer 14.

In the second step, referring to FIG. 2 and FIG. 3 together, the first dry film 20 is exposed and developed to form a first dry film pattern 22 on the first dry film 20.

Referring to FIG. 3, a plurality of first openings 220 are formed on the first dry film pattern 22. A portion of the first copper foil layer 14 is exposed from the plurality of first openings 220.

In the third step, referring to FIG. 4, the copper foil substrate 10 is electroplated to form the first conductive layer 30 on the first copper foil layer 14.

The first conductive layer 30 fills the first openings 220. In this embodiment, a thickness of the first conductive layer 30 is smaller than a thickness of the first dry film 20.

In other embodiments, the thickness of the first conductive layer 30 may be greater than or equal to the thickness of the first dry film 20.

In the fourth step, referring to FIG. 5, the first dry film 20 is removed from the first copper foil layer 14. The thickness of the first conductive layer 30 is greater than the thickness of the first copper foil layer 14. The first conductive layer 30 includes a plurality of first conductive pads 32.

Fifth step, referring to FIG. 6, a second dry film 40 is provided, and the second dry film 40 is laminated and laminated on the first copper foil layer 14 and the first conductive layer 30. The second dry film 40 is a photosensitive cover film.

In the sixth step, referring to FIG. 7 and FIG. 8 together, the second dry film 40 is exposed and developed to form a second dry film pattern 42.

In this step, the second dry film pattern 42 covers the first conductive layer 30 and covers a part of the first copper foil layer 14. The part of the first copper foil layer 14 surrounds the first conductive layer 30. The second dry film pattern 42 includes a plurality of second openings 420. The first copper foil layer 14 is exposed from the plurality of second openings 420.

Seventh step, referring to FIG. 9, the first copper foil layer 14 is etched, the first copper foil layer 14 is fabricated into a second conductive layer 50 having a circuit pattern, and a circuit layer is formed on the insulating layer 12 60.

The circuit pattern of the second conductive layer 50 corresponds to the circuit pattern of the first conductive layer 30.

Eighth step, referring to FIG. 10, peeling off the second dry film 40 on the second conductive layer 50 and the first conductive layer 30 to make the second conductive layer 50 and the first conductive layer 30 Exposed. The second conductive layer 50 includes a plurality of second conductive pads 52. The second conductive layer 50 and the first conductive layer 30 Together, the wiring layer 60 is formed. The circuit layer 60 includes the first conductive layer 30 and the second conductive layer 50 stacked on top of each other. The circuit layer 60 includes a plurality of bonding pads 70. The bonding pad 70 includes a first conductive pad 32 and a second conductive pad 52. The second conductive pad 52 is disposed on the insulating layer 12. The first conductive pad 32 is fixed on the second conductive pad 52. The thickness of the second conductive pad 52 is smaller than the thickness of the first conductive pad 32. The second conductive pad 52 has a protruding portion 54 opposite to the first conductive pad 32. The protruding portion 54 surrounds the first conductive pad 32.

Ninth step, referring to FIG. 11, a nickel plating layer 80 is plated on the surface of the pad 70, and a gold plating layer 90 is plated on the surface of the nickel plating layer 80 to complete the circuit board 100. Production.

The nickel plating layer 80 is disposed on the insulation layer 12 and covers the solder pad 70. The gold plating layer 90 is disposed on the insulating layer 12 and covers the nickel plating layer 80.

Referring to FIG. 11, the circuit board 100 includes the insulating layer 12, the bonding pad 70, the nickel plating layer 80, and the gold plating layer 90. The pads 70, the nickel plating layer 80, and the gold plating layer 90 are all disposed on the insulation layer 12. The nickel plating layer 80 covers the upper surface and the side surfaces of the bonding pad 70. The gold plating layer 90 covers the nickel plating layer 80. The bonding pad 70 includes the second conductive pad 52 and the first conductive pad 32. The second conductive pad 52 is disposed on the insulating layer 12. The first conductive pad 32 is disposed on the second conductive pad 52. The thickness of the second conductive pad 52 is smaller than the thickness of the first conductive pad 32. The second conductive pad 52 has a protruding portion 54 opposite to the first conductive pad 32. The protruding portion 54 surrounds the first conductive pad 32.

The top of the first conductive pad 32 extends in a direction close to the gold plating layer 90. A cross-sectional shape of the protruding portion 54 along a direction perpendicular to the insulating layer 12 is one of a triangle, a rectangle, and a trapezoid. The cross-sectional shape of the protruding portion 54 is not limited to this.

Wherein, the vertical height of the highest point of the protruding portion 54 from the upper surface of the insulating layer 12 is h; the total thickness of the second conductive pad 52 and the first conductive pad 32 is T; the nickel plating layer 80 The total thickness of the gold-plated layer 90 is H, where: h + H ≦ T.

The width of the protruding portion 54 protruding from the first conductive pad 32 is d, where: d ≦ T / 3.

The circuit board provided by the present invention and a manufacturing method thereof include the solder pad 70, and the solder pad 70 includes the second conductive pad 52 and the first conductive pad 32. The second conductive pad 52 is disposed on the insulating layer 12, the first conductive pad 32 is disposed on the second conductive pad 52, and the thickness of the second conductive pad 52 is smaller than that of the first conductive pad 32, the second conductive pad 52 has a protruding portion 54 opposite to the first conductive pad 32, the protruding portion 54 surrounds the first conductive pad 32, and the protruding portion 54 extends near the gold plating layer 90 It is provided to replace the nickel-plated layer 80 to preferentially react with the air and moisture entering between the gold-plated layer 90, the nickel-plated layer 80 and the insulating layer 12, and delay the reaction between the nickel-plated layer 80 and the air and moisture. The reaction time prevents the gold plating layer 90 from peeling off the circuit board 100 to a certain extent.

Understandably, for those having ordinary knowledge in the art, various other corresponding changes and deformations can be made according to the technical concept of the present invention, and all these changes and deformations should belong to the protection scope of the present invention.

Claims (8)

A method for manufacturing a circuit board includes the steps of: providing a first copper foil layer and an insulating layer, the first copper foil layer being fixedly disposed on the insulating layer; and forming and forming a first copper foil layer surface A first conductive layer having a circuit pattern, the first conductive layer including a plurality of first conductive pads; etching the first copper foil layer to obtain a second conductive layer, and making the circuit pattern of the second conductive layer and the second conductive layer The circuit pattern of the first conductive layer corresponds directly. The second conductive layer includes a plurality of second conductive pads. The thickness of the second conductive pad is smaller than the thickness of the first conductive pad. The second conductive pads collectively constitute a soldering pad of the circuit board. Each first conductive pad is disposed on a corresponding second conductive pad, and the second conductive pad has a protruding portion relative to the first conductive pad. The protruding portion surrounds the first conductive pad; and a nickel-plated gold layer is plated on the upper surface and the side surface of the solder pad. The method for manufacturing a circuit board according to claim 1, wherein a cross-sectional shape of the protruding portion in a direction perpendicular to the insulating layer is one of a triangle, a rectangle, and a trapezoid. The method for manufacturing a circuit board according to claim 1, wherein after the step of forming the first conductive layer having a pattern, etching the first copper foil layer to obtain a second conductive layer further includes the following steps, providing: A second dry film, the second dry film is pasted on the first copper foil layer and the first conductive layer, and the second dry film forms a second dry film pattern through exposure and development, so The second dry film pattern covers the first conductive layer, and covers the first copper foil layer that partially surrounds the first conductive layer, and the first dry film pattern is not covered by the second dry film pattern. The copper foil layer was removed by etching. The method for manufacturing a circuit board according to claim 1, wherein the step of forming a patterned first conductive layer on the surface of the first copper foil layer includes: providing a first dry film; A dry film is pasted on the first copper foil layer, and the first dry film is exposed, developed, copper-plated, and peeled to obtain the first conductive layer. A circuit board includes an insulating layer, a solder pad, and a nickel-plated gold layer. The solder pad and the nickel-plated gold layer are both disposed on the insulating layer, and the nickel-plated gold layer covers the The solder pad includes a first conductive pad and a second conductive pad, the second conductive pad is disposed on the insulating layer, the first conductive pad is disposed on the second conductive pad, and the first The thickness of the two conductive pads is smaller than the thickness of the first conductive pad, and the second conductive pad has a protruding portion opposite to the first conductive pad, and the protruding portion surrounds the first conductive pad; the nickel-plated gold layer Refers to nickel plating and gold plating. The circuit board according to claim 5, wherein an end portion of the second conductive pad is one of a triangle, a rectangle, and a trapezoid in a cross-sectional shape in a direction perpendicular to the insulating layer. The circuit board according to claim 5, wherein the vertical height of the highest point of the second conductive pad from the upper surface of the insulating layer is h; the total thickness of the second conductive pad and the first conductive pad is T; the total thickness of the nickel-plated gold layer is H; wherein: h + H ≦ T. The circuit board according to claim 7, wherein the width of the end of the second conductive pad protruding from the first conductive pad is d, where: d ≦ T / 3.