TWI735019B - Circuit board and method for making the same - Google Patents

Abstract

A method for making a circuit board comprises: providing a copper foil and covering a dielectric layer on the copper foil, the copper foil having first patterned openings; electroplating copper in the first patterned openings to form a copper plating layer; etching a portion of the copper plating layer to form a first inner wiring layer, thereby obtaining a circuit substrate; successively forming an insulating layer and an outer wiring layer on at least one surface of the circuit substrate, thereby obtaining the circuit board. The present disclosure further provides a circuit board making by the above method.

Description

Circuit board and preparation method of circuit board

The invention relates to a circuit board and a preparation method of the circuit board.

As the functions of portable electronic devices such as mobile phones continue to increase, circuit boards are also developing in the direction of diversification and multiple categories. Although the light, thin, short, and small circuit boards are the future development trend, however, based on the requirements of carrying current, heat dissipation, impedance control, etc. (for example, the increase in power consumption of electronic equipment causes the power supply to not meet the endurance requirements of electronic equipment, due to the rapid The charging technology solves this problem to a certain extent, so the circuit board is required to meet the needs of high current charging), and the circuit board is required to have a larger copper thickness.

The quality of thick copper plates produced by traditional processes is difficult to meet the requirements, and there will be problems of side corrosion.

In view of this, the present invention provides a method that can be used to prepare a circuit board with a relatively large copper thickness, which can avoid side corrosion.

In addition, it is also necessary to provide a circuit board obtained by the above-mentioned manufacturing method.

The present invention provides a method for preparing a circuit board, which includes: providing a copper foil layer and covering a surface of the copper foil layer with a dielectric layer, the dielectric layer including a first pattern opening; Copper is electroplated to form a copper plating layer; at least part of the copper foil layer is etched to form a first inner conductive circuit, thereby obtaining a circuit substrate; and an insulating layer and an insulating layer are sequentially formed on at least one surface of the circuit substrate The outer conductive circuit, thereby obtaining the circuit board.

The present invention also provides a circuit board, including: a dielectric layer, the dielectric layer includes a pattern opening; a first inner conductive line, including a first conductor part and a second conductor part, the first conductor part is located at the In the pattern opening, the second conductor part is formed on the first conductor part, and the projections of the first conductor part and the second conductor part in the extension direction perpendicular to the circuit board coincide with each other; A second inner conductive circuit is formed on the dielectric layer, the circuit thickness of the first inner conductive circuit is greater than the circuit thickness of the second inner conductive circuit; at least one insulating layer covers the first inner Conductive circuit; and at least one outer conductive circuit, each of the outer conductive circuit is formed on one of the insulating layers.

Compared with the prior art, in the present invention, since the thickness of the copper plating layer can be adjusted by controlling the plating time, thick copper circuits can be obtained by setting the plating time; because only the copper foil layer is etched (not embedded in the The copper-plated layer of the dielectric layer is etched), therefore, it is beneficial to reduce the thickness of the copper to be etched and avoid side corrosion; moreover, because the copper-plated layer is directly formed in the pattern opening, and the The sidewalls of the pattern openings can be arranged perpendicular to the copper foil layer, so the sides of the copper plating layer are also arranged perpendicularly, so as to prevent side corrosion caused by etching of thick circuits and facilitate the preparation of conductive circuits with large thickness and small spacing.

10: Copper foil layer

11: Copper plating layer

12: Graphical dry film

20: Dielectric layer

21: The first graphic opening

30: The first protective layer

40: second protective layer

50: Insulation layer

60: The second copper foil layer

61: Outer conductive circuit

70: Solder mask

100: Circuit board

101: The first inner conductive line

102: second inner conductive circuit

120: second graphic opening

200a, 200b, 200c: circuit board

1011: The first conductor part

1012: second conductor part

Fig. 1 is a cross-sectional view of the first copper foil layer provided by the present invention.

2 is a cross-sectional view of the copper foil layer shown in FIG. 1 after being covered with a dielectric layer.

FIG. 3 is a cross-sectional view after opening a first pattern opening in the dielectric layer shown in FIG. 2.

4 is a cross-sectional view of the first copper foil layer shown in FIG. 3 after covering the first protective layer.

FIG. 5 is a cross-sectional view after a copper plating layer is formed in the first pattern opening shown in FIG. 4.

FIG. 6 is a cross-sectional view after the first protective layer shown in FIG. 5 is removed.

FIG. 7 is a cross-sectional view of the dielectric layer and the copper plating layer shown in FIG. 6 after being covered with a second protective layer.

FIG. 8 is a cross-sectional view after etching a part of the first copper foil layer shown in FIG. 7 in the first embodiment of the present invention.

FIG. 9 is a cross-sectional view of the circuit substrate obtained by removing the second protective layer shown in FIG. 8.

Fig. 10 is a cross-sectional view of the circuit substrate shown in Fig. 9 after an insulating layer and a second copper foil layer are formed.

11 is a cross-sectional view of the circuit board obtained by etching the second copper foil layer shown in FIG. 10 and covering the solder resist layer.

FIG. 12 is a cross-sectional view of the first copper foil layer shown in FIG. 7 after being covered with a patterned dry film in the second embodiment of the present invention.

FIG. 13 is a cross-sectional view of part of the first copper foil layer shown in FIG. 12 after etching.

14 is a cross-sectional view of the first copper foil layer shown in FIG. 7 after being covered with a patterned dry film in the third embodiment of the present invention.

FIG. 15 is a cross-sectional view of part of the first copper foil layer shown in FIG. 14 after etching.

Fig. 16 is a cross-sectional view of the circuit board formed after Fig. 13 is continued to be manufactured.

Fig. 17 is a cross-sectional view of the circuit board formed after Fig. 15 is continued to be manufactured.

The present invention will be further described below in conjunction with the drawings and embodiments.

The first embodiment

1 to 11, the first embodiment of the present invention provides a method for manufacturing a circuit board, including the following steps: Step S1, please refer to FIG. 1, providing a first copper foil layer 10.

Step S2, referring to FIG. 2, a dielectric layer 20 is covered on the surface of the first copper foil layer 10.

In this embodiment, the material of the dielectric layer 20 can be selected from epoxy resin, polypropylene (PP), BT resin, polyphenylene oxide (PPO), polypropylene (polypropylene), etc. , PP), polyimide (PI), polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) and other resins.

The dielectric layer 20 can be formed by coating.

Step S3, referring to FIG. 3, a first pattern opening 21 is opened in the dielectric layer 20.

In this embodiment, the first pattern opening 21 can be opened by a laser process.

Step S4, referring to FIG. 4, a first protective layer 30 is covered on the surface of the first copper foil layer 10 away from the dielectric layer 20.

Wherein, the first protective layer 30 may be a dry film.

Step S5, referring to FIG. 5, electroplating copper in the first pattern opening 21 to form a copper plating layer 11.

It can be understood that the copper plating layer 11 can be formed by one or at least two electroplating steps. The thickness of the copper plating layer 11 can be adjusted by controlling the plating time. The thickness of the copper-plated layer 11 may be approximately equal to the thickness of the dielectric layer 20, so the dielectric layer 20 may be coated according to the required thickness of the copper-plated layer 11. Furthermore, since the electroplating solution may have different concentrations at different depths, it can be During the plating process or between two plating steps, the orientation of the first copper foil layer 10 is changed (for example, upside down), so as to improve the uniformity of the thickness of the copper plating layer 11.

Step S6, referring to FIG. 6, remove the first protective layer 30.

Further, the surface of the dielectric layer 20 and/or the copper-plated layer 11 away from the first copper foil layer 10 can be ground, so that the surfaces of the dielectric layer 20 and the copper-plated layer 11 are flush. .

Step S7, referring to FIG. 7, a second protective layer 40 is covered on the dielectric layer 20 and the copper plating layer 11.

Wherein, the second protective layer 40 may be a dry film.

Step S8, referring to FIG. 8, at least part of the first copper foil layer 10 is etched to form a first inner conductive circuit 101.

In this embodiment, the first copper foil layer 10 is completely etched, and at this time, the first inner conductive circuit 101 only includes the copper plating layer 11.

Step S9, referring to FIG. 9, the second protective layer 40 is removed, and a circuit substrate 100 is obtained.

In step S10, referring to FIG. 10, an insulating layer 50 and a second copper foil layer 60 are successively formed on the two opposite surfaces of the circuit substrate 100.

In this embodiment, the material of the insulating layer 50 can be selected from epoxy resin, polypropylene (PP), BT resin, polyphenylene oxide (PPO), polypropylene (polypropylene, PP), polyimide (PI), polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) and other resins. Optionally, the material of the insulating layer 50 is polypropylene.

Step S11, referring to FIG. 11, each second copper foil layer 60 is etched to form an outer conductive circuit 61, and a solder mask 70 is covered on the outer conductive circuit 61, thereby obtaining the circuit board 200a.

In this embodiment, the material of the solder mask 70 is solder mask ink. The solder mask 70 can be used to expose a portion of the outer conductive circuit 61 to form a plurality of solder pads (not shown).

Second embodiment

The second embodiment of the present invention provides a method for manufacturing a circuit board, and the method in steps S1 to S7 is the same as that of the first embodiment, which will not be repeated here. The difference from the first embodiment is:

As shown in FIG. 12, in step S8, a patterned dry film 12 is first covered on the first copper foil layer 10. The patterned dry film 12 includes a second pattern opening 120, and the second pattern opening 120 is used to expose part of the dielectric layer 20. That is, the area of the patterned dry film 12 excluding the second pattern opening 120 corresponds to the copper plating layer 11 and another part of the dielectric layer 20.

Then, as shown in FIG. 13, the first copper foil layer 10 is etched using the patterned dry film 12 as a mask. At this time, the copper-plated layer 11 (hereinafter referred to as "the first conductor portion 1011") and the area of the first copper foil layer 10 corresponding to the copper-plated layer 11 (hereinafter referred to as: "the second conductor The portion 1012") collectively forms the first inner conductive circuit 101. After the first copper foil layer 10 is etched, a second inner conductive circuit 102 is formed, and the second inner conductive circuit 102 is formed on the dielectric layer 20. The circuit thickness of the first inner conductive circuit 101 is greater than the circuit thickness of the second inner conductive circuit 102.

The third embodiment

The second embodiment of the present invention provides a method for preparing a circuit board, and the method in steps S1 to S7 is the same as that of the second embodiment, which will not be repeated here. The difference from the second embodiment is:

As shown in FIG. 14, in step S8, the second pattern opening 120 of the patterned dry film 12 is used to expose all the copper plating layer 11. As shown in FIG. 15, after the first copper foil layer 10 is etched with the patterned dry film 12 as a photomask, only the first inner conductive circuit 101 is formed, and the first inner conductive circuit 101 includes the first copper foil layer. A conductor portion 1011 and the second conductor portion 1012.

In the above preparation method, the thickness of the copper-plated layer 11 can be adjusted by controlling the electroplating time, so a thick copper circuit can be obtained by setting the electroplating time. Since only the first copper foil layer 10 is etched (the copper plating layer 11 embedded in the dielectric layer 20 is not etched), it is beneficial to reduce the etched copper thickness and avoid side etching. . Moreover, since the copper-plated layer 11 is directly formed in the first pattern opening 21, and the sidewalls of the first pattern opening 21 can be arranged perpendicular to the first copper foil layer 10, the copper-plated layer 11 The side surface of the layer 11 is also arranged vertically to prevent side corrosion caused by the etching of thick lines, which is beneficial to the preparation of conductive lines with large thickness and small spacing (for example, the thickness is 2OZ and the time interval is up to 50-100 microns, and the thickness is 3OZ. The time interval is up to 75-175 microns).

Referring to FIG. 11, the present invention also provides a circuit board 200a manufactured by the manufacturing method of the above-mentioned first embodiment. The circuit board 200a includes a dielectric layer 20, a first inner conductive circuit 101, and at least one insulating layer 50. And at least one outer conductive circuit 61.

The dielectric layer 20 includes a first pattern opening 21. The first inner conductive line 101 includes a first conductor portion 1011. The first conductor portion 1011 is located in the first pattern opening 21.

The insulating layer 50 covers the first inner conductive circuit 101. Each of the outer conductive lines 61 is formed on one of the insulating layers 50.

In this embodiment, the circuit board 200 further includes at least one solder mask 70, and each of the solder mask 70 covers one of the outer conductive circuits 61.

Referring to FIG. 16, the present invention also provides a circuit board 200b manufactured by the manufacturing method of the second embodiment described above. The difference from the circuit board 200a is that the first inner conductive line 101 further includes a second conductor portion 1012, the second conductor portion 1012 is formed on the first conductor portion 1011, and the first conductor The projections of the portion 1011 and the second conductor portion 1012 along the extending direction perpendicular to the circuit board 200 overlap with each other. The circuit board 200b further includes a second inner conductive circuit 102, the second inner conductive circuit 102 is formed on the dielectric layer 20, and the circuit thickness of the first inner conductive circuit 101 is greater than that of the second inner conductive circuit. The line thickness of the line 102. The height of the second conductor portion 1012 is equal to the height of the second inner conductive line 102.

Referring to FIG. 17, the present invention also provides a circuit board 200c manufactured by the manufacturing method of the third embodiment described above. The difference from the circuit board 200b is that the second inner conductive circuit 102 can be omitted.

Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out. Modifications or equivalent replacements should not depart from the spirit and scope of the technical solutions of the present invention.

11: Copper plating layer

20: Dielectric layer

50: Insulation layer

61: Outer conductive circuit

70: Solder mask

101: The first inner conductive line

200a: circuit board

Claims (7)

A method for preparing a circuit board includes: providing a copper foil layer and covering a surface of the copper foil layer with a dielectric layer, the dielectric layer including a first pattern opening; and electroplating copper in the first pattern opening To form a copper-plated layer; cover the copper foil layer with a patterned dry film, the patterned dry film includes a second pattern opening, the second pattern opening corresponds to a part of the dielectric layer, the pattern The area of the dry film except for the second pattern opening corresponds to the copper plating layer and another part of the dielectric layer; the copper foil layer is etched using the patterned dry film as a mask to make the copper foil layer The area corresponding to the copper-plated layer and the copper-plated layer together form a first inner conductive circuit. After the copper foil layer is etched, a second inner conductive circuit is also formed. The second inner conductive circuit is formed on the On the dielectric layer, a circuit substrate is obtained; and an insulating layer and an outer conductive circuit are sequentially formed on at least one surface of the circuit substrate to obtain the circuit board. The method for manufacturing a circuit board according to claim 1, wherein the circuit thickness of the first inner conductive circuit is greater than the circuit thickness of the second inner conductive circuit. The method for manufacturing a circuit board according to claim 1, wherein the copper-plated layer is formed by at least two electroplating steps, and the orientation of the copper foil layer is changed between each two electroplating steps, so as to obtain the copper-plated layer Floor. The method for manufacturing a circuit board according to claim 1, wherein the first pattern opening is opened by a laser process. A circuit board includes: a dielectric layer, the dielectric layer includes a pattern opening; a first inner conductive line, including a first conductor portion and a second conductor portion, the first conductor portion is located in the pattern opening , The second conductor part is formed on the first conductor part, and the projections of the first conductor part and the second conductor part along the extension direction perpendicular to the circuit board overlap each other; a second inner side A conductive circuit formed on the dielectric layer, the circuit thickness of the first inner conductive circuit is greater than the circuit thickness of the second inner conductive circuit; at least one insulating layer covering the first inner conductive circuit; and At least one outer conductive circuit, and each outer conductive circuit is formed on one of the insulating layers. The circuit board according to claim 5, wherein the height of the second conductor portion is equal to the height of the second inner conductive line. The circuit board according to claim 5, further comprising at least one solder mask, and each solder mask covers one of the outer conductive lines.

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