TWI780783B - Method for manufacturing printed circuit board and printed circuit board with protective layer - Google Patents

Abstract

The present invention provides a method for manufacturing a printed circuit board including the following steps: providing a first circuit board comprising a first dielectric layer and a metal wiring structure, wherein the metal wiring structure is formed on the first dielectric and comprises a first part and a second part; covering a protective layer on the first part; pressing a second dielectric layer on the second part; forming a covering layer on the surface of the first dielectric layer; forming an opening in the covering layer to expose the protective layer; removing the protective layer with an alkaline solution. The manufacturing cost of the printed circuit board can be reduced by the manufacturing method of the present invention.

Description

Manufacturing method of printed circuit board and printed circuit board with protective layer

The present invention relates to a method for manufacturing a printed circuit board, in particular to a method for manufacturing a printed circuit board in which a high temperature resistant protective layer is used to protect the metal circuit layer during the layering process of the printed circuit board.

With the miniaturization of electronic equipment and supplies, the design of electronic components and printed circuit boards has become more and more complicated. During the process of building up layers of printed circuit boards, many metal circuits need temporary protection. In the existing manufacturing method of protective metal circuit layer, the commonly used method is to use a temporary protective cover to cover the area to be protected, and then use mechanical or laser cutting to remove the outer frame after the subsequent lamination process is completed. ; Or use a photocurable protective adhesive for protection, and then remove it by physical stripping after the subsequent lamination process is completed. These methods all have the problems of production efficiency and manpower consumption, resulting in high processing costs.

In view of the above technical problems, the object of the present invention is to provide a method for manufacturing printed circuit boards with simple manufacturing process, convenient operation and cost saving.

To achieve the above object, the present invention provides a method of manufacturing a printed circuit board, which includes the following steps: providing a first circuit board, which includes: a first dielectric layer and a metal circuit structure, wherein the metal circuit structure is formed On one surface of the first dielectric layer, and the metal wiring structure includes a first part and a second part; covering a protective layer on the first part; laminating a second dielectric layer on the second part so that the second dielectric layer covers the second part; a covering layer is formed on the surface of the first dielectric layer to cover the surface of the protective layer and the surface of the second dielectric layer; on the covering layer An opening is formed in the middle to expose the protective layer; the protective layer is removed with an alkaline solution, wherein the protective layer is formed by a resin composition, and the resin composition includes: an alkali-soluble filler; an alkali-soluble solvents; solvents; and photoinitiators.

Preferably, the alkali-soluble filler includes zinc oxide, aluminum hydroxide, titanium dioxide, antimony trioxide or beryllium hydroxide.

Preferably, the particle size of the alkali-soluble filler is 0.1 micron to 10 micron.

Preferably, the alkali-soluble filler accounts for 50-90% by weight of the total weight of the resin composition.

Preferably, the alkali-soluble resin comprises polyimide, polyamic acid or phenolic resin.

Preferably, the first dielectric layer includes uncured or semi-cured thermosetting resin material.

Preferably, the second dielectric layer includes uncured or semi-cured curable resin material.

Preferably, after the second dielectric layer covers the second portion, a resin diffusion layer is formed on the side of the second dielectric layer.

Preferably, the covering layer includes a circuit board.

Preferably, the alkaline solution is a 3-5% aqueous alkali metal hydroxide solution.

The present invention also provides a printed circuit board with a protective layer, which includes: a first circuit board, which includes: a first dielectric layer and a metal wiring structure, wherein the metal wiring structure is formed on one of the first dielectric layers on the surface, and the metal wiring structure includes a first part and a second part; a protective layer covering the first part; a second dielectric layer covering the second part; wherein the protective layer is The alkali-soluble one is formed by a resin composition, and the resin composition system includes: an alkali-soluble filler; an alkali-soluble resin; a solvent; and a photoinitiator.

Preferably, the printed circuit board with protective layer further includes a covering layer, which is formed on the second dielectric layer in contact with it. More preferably, both the cover layer and the second dielectric layer surround the protection layer.

Preferably, the printed circuit board with protective layer further includes a resin diffusion layer, and the resin diffusion layer is arranged on the side of the second dielectric layer.

The present invention uses an alkali-soluble resin composition as a protective layer in a printed circuit board, and correspondingly matches a specific manufacturing process, thereby providing a method for manufacturing a printed circuit board with simple manufacturing process, convenient operation and cost saving.

In the present invention, if the terms "first" and "second" are used to describe a component, the component is not limited by the term, which is mainly used to distinguish one component from another component.

The manufacturing method of the printed circuit board provided by the present invention includes the following steps: providing a first circuit board, which includes: a first dielectric layer and a metal circuit structure, wherein the metal circuit structure is formed on the first dielectric layer On one surface, and the metal circuit structure is composed of a first part and a second part; covering a protective layer on the first part; covering a protective layer on the first part; laminating a second dielectric layer on the On the second part, so that the second dielectric layer covers the second part; forming a covering layer on the surface of the first dielectric layer, so as to cover the surface of the protective layer and the surface of the second dielectric layer; An opening is formed in the cover layer to expose the protective layer; the protective layer is removed with an alkaline solution, wherein the protective layer is formed of a resin composition, and the resin composition system includes: an alkali-soluble filler agent; alkali-soluble resin; solvent; and photoinitiator.

In the present invention, the press bonding can be performed using heat press bonding. This thermocompression bonding can be performed at 180-250°C.

The manufacturing method of the printed circuit board of the present invention will be described in detail below, which is only for illustrative purposes and not intended to limit the scope of the present invention.

1A to 1F are schematic flow charts of a method for manufacturing a printed circuit board according to an embodiment of the present invention. In order to be more clear about the structure of the printed circuit board produced in this embodiment, please also refer to the second figure, which is a schematic top view of the printed circuit board produced in this embodiment. Please refer to FIG. 1A first, the manufacturing method of the printed circuit board 10 of this embodiment is to firstly provide the first circuit board 100 . The first circuit board 100 includes a first dielectric layer 110 and a metal circuit structure 120 . The first dielectric layer 110 has a first surface 110a and a second surface 110b opposite to the first surface. In this embodiment, the metal circuit structure 120 is formed on the first surface 110 a of the first dielectric layer 110 . The metal circuit structure 120 can be composed of a plurality of metal circuits separated from each other. In this embodiment, the metal circuit is made of copper. The area defined between the two dotted lines A in Figure 1A is the first part. The area defined by the two dotted lines B and the two dotted lines C is the second part, which is used as the bottom of the stacked second dielectric layer. As shown in Figure 1A, in this embodiment, the metal circuit structure 120 includes a first part and a second part, wherein the first part is the part of the metal circuit structure 120 that needs to be protected, and the second part is the metal circuit that does not need to be protected. part that surrounds the first part. In some embodiments, the shortest distance d between the first part and the second part of the metal circuit structure 120 is between 0-0.5 mm. In some implementations, the part of the metal circuit structure other than the first part is the second part, that is, the shortest distance between the first part and the second part is zero. In this embodiment, the shortest distance between the first part and the second part is greater than 0 mm and less than 0.5 mm. In the present invention, the first dielectric layer 110 may be an uncured or semi-cured curable resin material (such as a thermosetting resin material).

After the first circuit board 100 is provided, as shown in FIG. 1B , a protective layer 111 is covered on the first part. In the present invention, screen printing, spray printing or photolithography can be used for patterning, the protective layer 111 is covered on the position of the metal circuit to be protected on the first circuit board 100, and the surface is dried at 90°C for 5 minutes , to form a protective layer 111 with high temperature resistance. The protective layer can withstand a high temperature of at least 160°C (such as: 160-300°C), and the thickness change rate of the protective layer before and after hot pressing can be less than 5%. In this embodiment, the protective layer 111 is formed by a resin composition, and the resin composition includes: an alkali-soluble filler; an alkali-soluble resin; a solvent; and a photoinitiator. In the present invention, the resin composition may be a photosensitive resin composition.

In the present invention, examples of the alkali-soluble filler include, but are not limited to: zinc oxide (ZnO), aluminum hydroxide (Al(OH) ₃ ), titanium dioxide (TiO ₂ ), antimony trioxide (Sb ₂ O ₃ ), beryllium hydroxide (Be(OH) ₂ ). These alkali-soluble fillers can be used individually or in combination of 2 or more types (for example, 3 types, 4 types). In a preferred embodiment, the particle size of the alkali-soluble filler is 0.1 micron to 10 micron, such as: 1 micron to 9 micron, 3 micron to 7 micron. In a preferred embodiment, the alkali-soluble filler accounts for 50-90% by weight of the total weight of the resin composition.

In the present invention, one of the functions of the alkali-soluble resin is as a wetting agent. The alkali-soluble resin may be a resin that is easily soluble in alkaline solution. Considering the solubility of the alkali-soluble resin to the alkaline solution, the alkali-soluble resin has alkali-soluble functional groups (such as carboxyl groups). The amount of carboxyl groups contained in the alkali-soluble resin may be 20-200 mgKOH/g in terms of acid value, preferably 45-120 mgKOH/g. In consideration of developability and peelability, the alkali-soluble resin must have a carboxyl group. Further considering the viewpoints of improving development resistance, resolution and adhesion, the acid value of the alkali-soluble resin having a carboxyl group is preferably at least 30 mgKOH/g, more preferably at least 50 mgKOH/g. On the other hand, the acid value of the alkali-soluble resin having a carboxyl group is preferably 200 mgKOH/g or less, more preferably 120 mgKOH/g or less, from the viewpoint of improving developability and peelability. Examples of alkali soluble resins include, but are not limited to: polyimides, polyamic acid, phenolic resins, combinations thereof. That is, these alkali-soluble resins can be used individually or in combination of 2 or more types. In consideration of improving resolution and developability, the weight average molecular weight of the alkali-soluble resin is preferably 5,000-300,000, more preferably 5,000-100,000, and most preferably 5,000-50,000 or less.

Examples of the solvent include, but are not limited to: N-methyl-2-pyrrolidone, N,N-dimethylacetamide, γ-butyrolactone, xylene, toluene, combinations thereof. That is, these solvents may be used alone or in combination of two or more (such as three or four).

In the present invention, the photoinitiator can be bis(2,4,6-trimethylbenzoyl)phenyl phosphorus oxide, 2,4,6-trimethylbenzoyl-diphenyl Phosphorus oxide or combinations thereof, but not limited thereto. These photoinitiators can be used alone or in combination of two or more (such as three or four). These photoinitiators can be used in combination with crosslinkers for photolithographic patterning.

After covering the protection layer 111 , as shown in FIG. 1C , a second dielectric layer 210 is pressed on the second portion so that the second dielectric layer 210 covers the second portion. In the present invention, the second dielectric layer 210 may be an uncured or semi-cured curable resin material (such as a thermosetting resin material). In this embodiment, the second dielectric layer 210 preformed with a first opening 210A is pressed on the second part of the first circuit board by thermocompression, and the first opening 210A can make the protection layer 111 The surface is completely exposed after the second dielectric layer 210 is pressed onto the second part. During the lamination process, part of the thermosetting resin material (that is, the second dielectric layer 210 ) will flow out to form a resin diffusion layer 211 on the side of the second dielectric layer 210 . After pressing, the diffusion layer is cured by heat. In the present invention, the inventors did not expect to find that using the above-mentioned resin composition, the width of the resin diffusion layer 211 formed by the composition can be suppressed within a certain range, and the following can be avoided: (1) resin diffusion The width of the layer is too large to cover the metal circuit, resulting in a poor process; and (2) the resin diffusion layer 211 is in contact with the protective layer 111, so that the protective layer 111 cannot be removed with an alkaline solution in the back-end process. Therefore, in the present invention, the distance between the resin diffusion layer 211 and the protection layer 111 on the first dielectric layer 110 is greater than 0 mm. Preferably, the distance is greater than 0mm and less than 0.5mm. In the present invention, the ratio of the height H ₁ of the protection layer to the height H ₂ of the second dielectric layer is preferably 1.0:1.0˜1.0:1.5. In this embodiment, the ratio of H ₁ :H ₂ is 1:1 as an example. In the present invention, the edge angle of the protection layer is preferably greater than 70 degrees. The so-called edge angle refers to the angle between the tangent line of the edge of the protective layer 111 and the horizontal line.

After laminating the second dielectric layer 210, as shown in FIG. 1D, a cover layer 310 is formed on the first surface 110a of the first dielectric layer to cover the surface of the protective layer 111 and the second dielectric layer. The surface of layer 210. In this embodiment, the covering layer 310 completely covers the second dielectric layer 210 and its opening (ie, the pre-formed first opening 210A mentioned above). In the present invention, the covering layer can be organic or inorganic. In a preferred embodiment, the cover layer 310 is a circuit board (second circuit board), so that a multilayer circuit board can be obtained.

After the covering layer 310 is formed, as shown in FIG. 1E , a second opening 310A is formed in the covering layer 310 to expose the protective layer 111 . In the present invention, the size of the second opening 310A and the size of the first opening may be the same or different. In a preferred embodiment, the size of the second opening is substantially the same as that of the first opening. In this embodiment, a portion of the covering layer is removed by laser cutting, and the portion of the covering layer is located above the protection layer 111 , so that after it is removed, the protection layer 111 can be partially or completely exposed. After the part of the covering layer is removed, a second opening 310A is formed, and in this embodiment, the size of the second opening is the same as that of the first opening.

As shown in FIG. 1F , after the protective layer 111 is completely exposed, the protective layer 111 is removed with an alkaline solution. In the present invention, the alkaline solution can be a 3-5% aqueous alkali metal hydroxide solution. The removal step is carried out at 35-60°C. The top view of the printed circuit board manufactured according to the above-mentioned manufacturing method is shown in FIG. 2 , where the dotted line area is used to represent the area covered by the protective layer 111 in FIG. 1E .

Based on the above manufacturing method, the present invention further provides a printed circuit board with a protective layer. As shown in Figure 1E, the printed circuit board 10 with a protective layer includes: a first circuit board 100, which includes: a first dielectric layer 110 and a metal wiring structure 120, wherein the metal wiring structure 120 is formed on On one surface of the first dielectric layer 110, and the metal circuit structure 120 comprises a first part and a second part; a protective layer 111 covers the first part; a second dielectric layer 210 covers the On the second part; wherein, the protective layer 111 is alkali-soluble and is formed of a resin composition, and the resin composition system includes: an alkali-soluble filler; an alkali-soluble resin; a solvent; and a photoinitiator agent.

In this embodiment, the printed circuit board with protective layer further includes a cover layer 310 , and the cover layer 310 is formed on the second dielectric layer 210 in contact with it. Please refer to the second figure, in this embodiment, the cover layer 310 and the second dielectric layer 210 both surround the protection layer 111 (not shown, only the position of the first part is shown by a dotted line).

It can be seen from the above that the protective layer of the present invention can be removed only by using an alkaline solution, without complicated laser cutting or physical stripping to remove the protective layer. Compared with the conventional technology, the manufacturing process can be greatly simplified, and the A method for manufacturing a printed circuit board with simple manufacturing process, convenient operation and cost saving is provided.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements can be made without departing from the technical principle of the present invention. and modifications, these improvements and modifications should also be considered as the protection scope of the present invention.

10: Printed circuit board 110 of the present invention: first dielectric layer 110a: first surface 110b: second surface 120: metal circuit structure d: shortest distance between the first part and the second part 111: protective layer H ₁ : protection Layer height 210: second dielectric layer 210A: first opening 211: resin diffusion layer H ₂ : height 310 of second dielectric layer: cover layer 310A: second opening

1A to 1F are schematic flow charts of a method for manufacturing a printed circuit board according to an embodiment of the present invention.

The second figure is a schematic top view of a printed circuit board manufactured by a manufacturing method according to an embodiment of the present invention.

none

120: Metal circuit structure

211: resin diffusion layer

310: Overlay

310A: second opening

Claims (14)

A method of manufacturing a printed circuit board, comprising the following steps: A first circuit board is provided, comprising: a first dielectric layer and a metal circuit structure, wherein the metal circuit structure is formed on one surface of the first dielectric layer, and the metal circuit structure comprises a first part and - the second part; covering a protective layer on the first part; pressing a second dielectric layer on the second part, so that the second dielectric layer covers the second part; forming a covering layer on the surface of the first dielectric layer to cover the surface of the protection layer and the surface of the second dielectric layer; forming an opening in the cover layer to expose the protection layer; This protective layer is removed with an alkaline solution, Wherein, the protective layer is formed by a resin composition, and the resin composition includes: an alkali-soluble filler; an alkali-soluble resin; a solvent; and a photoinitiator. The manufacturing method according to claim 1, wherein the alkali-soluble filler includes zinc oxide, aluminum hydroxide, titanium dioxide, antimony trioxide or beryllium hydroxide. The manufacturing method according to claim 1, wherein the particle size of the alkali-soluble filler is 0.1 micron to 10 micron. The manufacturing method according to claim 1, wherein the alkali-soluble filler accounts for 50-90% by weight of the total weight of the resin composition. The manufacturing method according to claim 1, wherein the alkali-soluble resin comprises polyimide, polyamic acid or phenolic resin. The manufacturing method according to claim 1, wherein the first dielectric layer comprises an uncured or semi-cured thermosetting resin material. The manufacturing method according to claim 1, wherein the second dielectric layer comprises uncured or semi-cured curable resin material. The manufacturing method according to claim 1, wherein after the second dielectric layer covers the second portion, a resin diffusion layer is formed on the side of the second dielectric layer. The manufacturing method according to claim 1, wherein the covering layer includes a circuit board. The manufacturing method as described in Claim 1, wherein the alkaline solution is a 3-5% aqueous alkali metal hydroxide solution. A printed circuit board with a protective layer, comprising: A first circuit board, which includes: a first dielectric layer and a metal wiring structure, wherein the metal wiring structure is formed on one surface of the first dielectric layer, and the metal wiring structure includes a first portion and a first wiring structure two parts; a protective layer covering the first part; a second dielectric layer covering the second portion; Wherein, the protective layer is alkali-soluble and formed by resin composition, and the resin composition system includes: alkali-soluble filler; alkali-soluble resin; solvent; and photoinitiator. The printed circuit board as claimed in claim 11, further comprising a cover layer, the cover layer is formed on the second dielectric layer in contact with it. The printed circuit board as claimed in claim 12, wherein both the covering layer and the second dielectric layer surround the protective layer. The printed circuit board according to claim 11, further comprising a resin diffusion layer disposed on the side of the second dielectric layer.

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