JP3861338B2 - Method for manufacturing printed wiring board - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a method for manufacturing a printed wiring board capable of forming an insulating layer having a flat surface.
[0002]
[Prior art]
Conventionally, as a printed wiring board, for example, as shown in FIG. 14, there is one in which a conductor circuit 92 is formed on the surface of a substrate 91 and these are covered with an insulating layer 93.
The insulating layer 93 is covered by a roll coater coating method. This is because the insulating resin is applied to the surface of the substrate 91 by applying an insulating resin to a pair of rolls and rolling them while applying a load while contacting the both sides of the substrate 91 on which the conductor circuit 92 is formed. It is a method of copying.
[0003]
After applying the insulating resin, the solvent in the insulating resin is volatilized and the insulating resin is dried. The degree of drying is such that the insulating resin does not adhere when the insulating resin coating surface is touched with a finger. As a result, an insulating layer 93 made of an insulating resin is formed on the surface of the substrate 91.
[0004]
[Problems to be solved]
However, in the conventional printed wiring board, the surface of the insulating layer 93 is uneven in proportion to the thickness of the conductor circuit 92 as shown in FIG. This unevenness causes a problem that when a conductor circuit is formed on the surface of the insulating layer 93, an exposure fogging occurs in the case of the semi-additive method, and a polishing residue after plating occurs in the case of the full additive method. Bring.
[0005]
In view of the conventional problems, the present invention is intended to provide a method for manufacturing a printed wiring board capable of forming an insulating layer having a flat surface.
[0006]
[Means for solving problems]
The invention of claim 1, a conductor circuit is formed on the surface of the substrate, then, a method for manufacturing a printed wiring board covering the insulating layer on the surface of the substrate including the conductor circuit,
After forming the blackening layer to the conductor circuit surface, the surface of the substrate, between adjacent said conductor circuit, a write-free process to fill the potting,
Applying a first insulating resin as a surface treatment material for protecting the blackening layer to the entire surface of the embedding resin and the conductor circuit to form a first insulating resin layer ;
Applying a second insulating resin obtained by adding a silica filler to the component of the first insulating resin to the surface of the first insulating resin layer to form a second insulating resin layer ;
Applying a third insulating resin obtained by adding an epoxy resin filler to the component of the first insulating resin to the surface of the second insulating resin layer to form a third insulating resin layer; ,
The printed wiring board manufacturing method characterized by including .
[0007]
The effect of this invention is demonstrated.
In the present invention, an embedding resin is provided between adjacent conductor circuits. Between adjacent conductor circuits is recessed lower than the surface of the conductor circuit. Therefore, by embedding the embedding resin between the concave conductor circuits, the surface of the embedding resin is close to the height of the surface of the conductor circuit, and the height between the two is approximated. Therefore, an insulating layer having a flat surface can be formed by applying an insulating resin to these surfaces.
[0008]
In the present invention, the surface of the insulating layer can be flattened even when the insulating resin is applied by the roll coater method.
The present invention can be applied to all methods for manufacturing a printed wiring board having a conductor circuit, including a semi-additive method and a full additive method.
[0009]
Next, the embedding resin is preferably embedded by screen printing. Thereby, embedding resin can be easily embedded.
[0010]
According to a second aspect of the present invention, the embedding resin is embedded by screen printing, and the screen printing uses a screen having a mesh portion narrower than between adjacent conductor circuits. preferable. Here, the mesh portion means a printable portion through which the embedding resin passes.
Thereby, the embedding resin that has passed through the mesh portion wraps outside the mesh portion between the conductor circuits, and the surface of the embedding resin becomes flat. Therefore, a flatter insulating layer can be formed by coating the surface of the flat embedding resin with an insulating resin.
This also prevents the embedding resin from adhering to the surface near the end of the conductor circuit. For this reason, after that, a surface treatment material for improving the adhesion between the conductor circuit and the insulating resin is applied to the conductor circuit, so that the surface treatment material uniformly covers the entire surface of the conductor circuit. Therefore, the adhesion between the insulating resin and the conductor circuit is reliably improved.
[0011]
It is preferable to embed an embedding resin between adjacent conductor circuits having an interval of 200 μm or more. As a result, an insulating layer having sufficient surface flatness can be formed only by an insulating resin applied thereafter without embedding a resin for embedding if the interval is between conductor circuits of less than 200 μm. Because.
[0012]
Further, when the interval between adjacent conductor circuits is 10 mm or less, embedding resin is preferably embedded. By embedding embedding resin between conductor circuits having an interval of 10 mm or less, even if the embedding resin is not embedded between conductor circuits having an interval exceeding 10 mm, a flat insulating layer is formed on the entire surface. it can.
[0013]
The embedding resin is preferably embedded to a height of at least 90% of the height of the conductor circuit. Thereby, the surface of the insulating layer can be made flatter. On the other hand, in the case where it is buried only to a height of less than 90%, the surface of the insulating layer may undulate.
The embedding resin is preferably embedded to a height of 110% or less of the height of the conductor circuit. Thereby, the surface of the insulating layer can be made flatter.
[0014]
Further, it is preferable that the embedding resin embedded between the adjacent conductor circuits has a flat surface. Thereby, when the insulating resin is applied to the surfaces of the flat embedding resin and the conductor circuit, the surface of the insulating layer can be made flatter.
[0015]
Further, after embedding the embedding resin, it is preferable to dry the embedding resin and polish the surface to make the surface flat, and then apply the insulating resin. Thereby, the surface of the embedding resin can be flattened, and further, the surface of the insulating resin layer can be further flattened.
[0016]
Next, as described in claim 3, after forming the insulating layer, a via hole is formed in the insulating layer, and then the inner wall of the via hole and the surface of the insulating layer are immersed in a roughening solution. Then, a metal plating process is performed to form a conductor layer on the inner wall of the via hole and a conductor circuit on the surface of the insulating layer, and the embedding resin is dissolved in the roughening solution. It preferably has properties. As a result, even when a part of the embedding resin adheres to the surface of the conductor circuit, the embedding resin is dissolved together with the soluble component in the insulating resin during the roughening treatment, so that the conductor The surface of the circuit is exposed. Therefore, by performing the metal plating process, a via hole conductor layer is reliably formed on the surface of the exposed conductor circuit. Therefore, the reliability of electrical connection with the conductor layer for the via hole is improved.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
The manufacturing method of the printed wiring board concerning the embodiment of this invention is demonstrated using FIGS.
As shown in FIG. 1, the printed wiring board 10 manufactured according to this example is provided with a conductor circuit 6 as an inner layer circuit on the surface of a substrate 7 and covering the surface with an insulating layer 2. A via hole 20 is opened in the insulating layer 2 toward the surface of the conductor circuit 6. Inside the via hole 20, a conductor layer 4 that is electrically connected to the conductor circuit 6 is provided.
A conductor circuit 40 as an outer layer circuit is provided on the surface of the insulating layer 2.
[0018]
Next, an outline of a method for manufacturing the printed wiring board will be described. First, the conductor circuit 6 to be an inner layer circuit is formed on the surface of the substrate 7 (FIG. 2). Next, the embedding resin 1 is embedded between the adjacent conductor circuits 6 on the surface of the substrate 7 (FIG. 3). Next, the insulating layer 2 is formed on the entire surface of the embedding resin 1 and the conductor circuit 6 (FIG. 5).
[0019]
Next, a via hole 20 is formed in the insulating layer 2 (FIG. 6). Next, the conductor layer 4 is formed on the inner wall of the via hole 20 and the conductor circuit 40 is formed on the surface of the insulating layer 2 by the semi-additive method (FIGS. 8, 9, and 1). Thereby, the printed wiring board 10 is obtained.
[0020]
Next, this will be described in detail.
First, as a starting material, a copper clad laminate is prepared by laminating a copper foil having a thickness of 30 to 40 μm on the surface of a resin substrate. Next, the copper foil is etched into a pattern to form a conductor circuit 6 serving as an inner layer circuit on the surface of the substrate 7 as shown in FIG.
Next, the substrate 7 is blackened, and a needle-like blackened layer having a thickness of 0.2 to 3 μm is formed on the entire surface of the conductor circuit 6 (not shown).
[0021]
Further, three types of photosensitive resins V1, V2, V3 having photosensitivity and an embedding resin are prepared as follows.
As will be described later, the insulating resin V1 is a surface treatment material for protecting the blackened layer and improving the adhesion between the conductor circuit and the insulating resin layer. Such an insulating resin V1 is prepared by uniformly kneading a mixture of a bisphenol A type epoxy resin and an imidazole curing agent with three rolls and adding a predetermined amount of solvent to the kneaded product.
[0022]
The insulating resin V2 is a material for forming the central portion of the insulating layer 2. The insulating resin V2 is prepared by uniformly kneading a component obtained by adding a silica filler to the component of the insulating resin V1 with three rolls and adding a predetermined amount of solvent to the kneaded product.
[0023]
The insulating resin V3 is a material for improving the adhesion between the insulating layer and the conductor circuit to be formed on the surface thereof. This insulating resin V3 is obtained by uniformly kneading a component of the insulating resin V1 to which an epoxy resin filler is added instead of silica with three rolls, and adding a predetermined amount of solvent to the kneaded product. Prepare.
[0024]
The embedding resin is a resin having a property of being dissolved in the roughening solution. Such embedding resin has the same composition as that of the insulating resin V2.
In addition to the above, as the embedding resin, for example, a novolac type epoxy resin or the like can be used.
[0025]
Next, as shown in FIG. 3, by embedding the embedding resin 1 between adjacent conductor circuits 6 on the surface of the substrate 7 by screen printing and drying it by touch, the embedding resin 1 is half-finished. Harden. The finger touch drying means drying in which the solvent is removed until the embedding resin does not adhere to the finger when the embedding resin is touched with the finger.
The thickness of the embedding resin 1 in a dry state of touch is 30 to 40 μm, which is substantially the same as the thickness of the conductor circuit 6. The screen 8 used in screen printing includes a mesh portion 80 that is narrower than between adjacent conductor circuits 6 and a mask portion 81 that covers the conductor circuits 6.
[0026]
A gap A of 0.3 to 0.5 mm is provided between the end of the conductor circuit 6 and the end of the mesh portion 80.
On the other hand, as shown in FIG. 4, when the gap A is less than 0.3 mm, the embedding resin 1 may adhere to the surface near the end of the conductor circuit 6 due to screen misalignment or the like. The surface of the embedding resin 1 may be flat. However, also in this case, the surface of the embedding resin 1 can be polished by means such as a belt sander, so that the embedding resin 1 attached to the surface near the end of the conductor circuit 6 can be removed. The surface of the embedding resin 1 can be flattened.
On the other hand, when the gap A exceeds 0.5 mm, the filling resin unfilled portion is generated as a wide depression between the conductor circuits 6, thereby forming a flat insulating layer. You may not be able to.
[0027]
Next, the substrate 7 after the blackening treatment is gently dipped into the pre-dip tank filled with the insulating resin V1. The dip conditions are 70 to 80 ° C. and 5 to 15 minutes. Next, the substrate 7 is gently pulled up, and then the insulating resin V1 attached to the surface is dried by touch. As a result, as shown in FIG. 5, a thin insulating resin layer 21 covering the conductor circuit 6 is formed on the surface of the substrate 7.
[0028]
Next, the insulating resin V2 is applied to the substrate 7 using a roll coater. Next, the insulating resin V2 is semi-cured by performing touch drying at 80 ° C. for 40 minutes. Thereby, the insulating resin layer 22 having a thickness of 30 to 80 μm is formed on the surface of the insulating resin layer 21.
[0029]
Next, the insulating resin V3 is applied to the substrate 7 on which the insulating resin layer 22 is formed using a roll coater. Thereafter, the applied insulating resin V3 is semi-cured by performing finger touch drying at 80 ° C. for 40 minutes. Thereby, an insulating resin layer 23 having a thickness of 20 to 50 μm is formed on the surface of the insulating resin 22.
[0030]
As described above, the insulating layer 2 composed of the insulating resin layers 21, 22, and 23 is formed on the entire surface of the embedding resin 1 and the conductor circuit 6.
The insulating resin V1, which is a surface treatment material, has a low solids weight ratio of 10%, and thus has a high fluidity, and uniformly covers and protects the blackened layer on the surface of the conductor circuit 6. In this state, by applying the insulating resins V2 and V3 in the next process using a roll coater, the influence of the roll coming into contact with the surface of the conductor circuit 6 is reduced. Further, since the insulating resin layer 21 has a surface roughness of 0.3 to 0.5 μm, the adhesion strength between the conductor circuit and the insulating resin layer 22 is improved.
[0031]
Next, as shown in FIG. 6, a via hole 20 is formed in the insulating layer 2 by performing exposure and development according to a general photolithography technique. At this time, a part of the upper surface of the conductor circuit 6 is exposed from the insulating layer 2.
Next, after the exposure and development, a photo / thermosetting process is performed to fully cure the embedding resin 1 and the insulating layer 2.
[0032]
Next, the resin filler in the insulating layer 2 is selectively dissolved by treating the substrate 7 with a roughening solution such as chromic acid. As a result, a roughened surface 29 is formed on the surface of the insulating layer 2 and the inner wall of the via hole 20 as shown in FIG. The embedding resin 1 present on the surface of the conductor circuit 6 is also dissolved and removed.
[0033]
Next, as shown in FIG. 8, after applying a catalyst nucleus to the surface of the insulating layer 2 and the inner wall of the via hole 20, an electroless copper plating layer 41 is formed. Next, a resist film 5 is formed on the surface of the insulating layer 2 where no conductor circuit is formed.
Next, an electrolytic copper plating layer 42 is formed on the inner wall of the via hole 20 and the conductor circuit forming portion on the surface of the electroless copper plating layer 41.
[0034]
Next, the resist film 5 is removed, and then quick etching is performed to remove the electroless plating film 41 formed in the portion where the conductor circuit is not formed. Thus, as shown in FIGS. 9 and 1, the inner wall of the via hole 20 is covered with the conductor layer 4 including the electroless copper plating layer 41 and the electrolytic copper plating layer 42, and the surface of the insulating layer 2 is covered with the electroless copper. A conductor circuit 40 including the plating layer 41 and the electrolytic copper plating layer 42 is formed.
Thus, the printed wiring board 10 is obtained.
[0035]
Next, the function and effect of this example will be described.
In this example, as shown in FIG. 3, the embedding resin 1 is provided between the adjacent conductor circuits 6. The space between adjacent conductor circuits 6 is recessed lower than the surface of the conductor circuit 6. Therefore, by embedding the embedding resin 1 between the concave conductor circuits 6, the surface of the embedding resin 1 becomes close to the height of the surface of the conductor circuit 6, and the heights of both are approximated. Become. Therefore, an insulating layer 2 having a flat surface can be formed by applying an insulating resin to these surfaces.
[0036]
The embedding resin is embedded between the adjacent conductor circuits 6 by screen printing. Therefore, the embedding resin can be easily embedded.
Further, as shown in FIG. 3, the screen 8 used in screen printing has a mesh portion 80 that is narrower than between adjacent conductor circuits 6. For this reason, the embedding resin 1 that has passed through the mesh portion 80 wraps outside the mesh portion 80 between the conductor circuits 6, and the surface of the insulating layer 2 can be made flatter. Further, the embedding resin does not adhere to the surface near the end of the conductor circuit 6. Therefore, the entire surface of the conductor circuit 6 can be covered with the thin insulating resin layer 21, and the adhesion between the insulating resin layer 22 forming the central portion and the conductor circuit 6 can be improved.
[0037]
The embedding resin has a property of dissolving in the roughening solution. For this reason, even when a part of the embedding resin 1 adheres to the surface of the conductor circuit 6, the embedding resin 1 is dissolved together with the resin filler in the insulating layer 2 during the roughening treatment, and the conductor The surface of the circuit 6 is exposed. Therefore, by performing electroless copper plating and electrolytic copper plating, the via hole conductor layer 4 is reliably formed on the exposed surface of the conductor circuit 6. Therefore, the electrical connection reliability between the conductor circuit 6 and the conductor layer 4 covering the via hole 20 is improved.
[0038]
In this example, the surface treatment of the conductor circuit with the insulating resin V1 was performed after screen printing of the embedding resin and touch-drying. The conductor circuit may be surface-treated with the resin V1 and the embedding resin may be dried by touching the resin.
[0039]
Embodiment 2
In this example, as shown in FIG. 10, the point that a fixed gap 100 is provided between the conductor circuit 6 and the embedding resin 1 is different from the first embodiment.
A gap 100 formed between the conductor circuit 6 and the embedding resin 1 is 0 to 200 μm, and a recess is recessed between the two. Insulating resin enters the gap 100 during the coating process. Even when an insulating resin enters the gap 100, the surface of the insulating layer 2 near the gap 100 can be kept flat.
[0040]
On the other hand, when the gap 100 exceeds 200 μm, the filling resin unfilled portion is generated as a wide depression between the conductor circuits 6, and thus a flat insulating layer may not be formed. is there.
Others are the same as in the first embodiment.
Also in this example, the same effects as those of the first embodiment can be obtained.
[0041]
Embodiment 3
In this example, as shown in FIG. 11, the embedding resin 1 is embedded when the interval between the conductor circuits 101 is 200 μm or more, and the embedding resin 1 is embedded between the conductor circuits 102 with the interval less than 200 μm. Do not embed.
By embedding the embedding resin 1 in the space 101 between the conductor circuits 6 having an interval of 200 μm or more, the insulating layer 2 having a flat surface can be formed. On the other hand, the embedding resin may be embedded even between the conductor circuits 102 having a distance of less than 200 μm, but the insulating layer 2 can be formed flat even when not embedded.
[0042]
Embodiment 4
In this example, as shown in FIGS. 12 and 13, the permanent resist film 51 is provided between the conductor circuits 40 which are outer layer circuits, and the formation of the conductor circuit 40 is performed in a fully additive manner instead of the semi-additive method. This is different from the first embodiment in that it is performed by the method.
[0043]
That is, as shown in FIG. 13, after making the surface of the insulating layer 2 and the inner wall of the via hole 20 into the roughened surface 29, the permanent resist film 51 is formed. Thereafter, electroless copper plating and electrolytic copper plating are performed to form the conductor circuit 40 on the surface of the insulating layer 2 and the conductor layer 4 on the inner wall of the via hole.
Others are the same as in the first embodiment.
[0044]
Also in this example, since the insulating layer 2 is formed after the embedding resin 1 is embedded between the conductor circuits 6, the surface of the insulating layer 2 can be formed flat as in the first embodiment. . In other respects, the same effects as those of the first embodiment can be obtained.
[0045]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the printed wiring board which can form the insulating layer with the flat surface can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a printed wiring board according to Embodiment 1;
2 is a cross-sectional view of a substrate on which a conductor circuit is formed in the method for manufacturing a printed wiring board according to Embodiment 1. FIG.
3 is a cross-sectional view of a substrate for illustrating a method of embedding an embedding resin between conductor circuits using a screen having a mesh portion narrower than that between conductor circuits, following FIG. 2;
FIG. 4 is a cross-sectional view of a substrate for illustrating a method of embedding an embedding resin between conductor circuits by using a screen having a mesh portion equivalent to that between conductor circuits.
FIG. 5 is a cross-sectional view of the substrate in which the surface of the conductor circuit and the embedding resin is covered with an insulating layer, following FIG. 3;
6 is a cross-sectional view of a substrate on which a via hole is formed, following FIG. 5;
7 is a cross-sectional view of the substrate after the roughening process is performed on the insulating layer, following FIG. 6;
FIG. 8 is a cross-sectional view of a substrate for illustrating a method for forming a conductor circuit and a conductor layer by a semi-additive method following FIG. 7;
FIG. 9 is a cross-sectional view of the substrate after the quick etching, continued from FIG. 8;
10 is a cross-sectional view of a printed wiring board in Embodiment 2. FIG.
11 is a cross-sectional view of a printed wiring board according to Embodiment 3. FIG.
12 is a cross-sectional view of a printed wiring board according to Embodiment 4. FIG.
FIG. 13 is a cross-sectional view of a substrate for illustrating a method for forming a conductor circuit and a conductor layer by a full additive method in Embodiment 4.
FIG. 14 is an explanatory view showing a method for manufacturing a printed wiring board in a conventional example.
[Explanation of symbols]
1. . . Embedding resin,
10. . . Printed wiring board,
2. . . Insulation layer,
20. . . Via hole,
21, 22, 23. . . Insulating resin layer,
4). . . Conductor layer,
40,6. . . Conductor circuit,
41. . . Electroless copper plating layer,
42. . . Electrolytic copper plating layer,
5). . . Resist film,
51. . . Permanent resist film,
7). . . substrate,
8). . . screen,
80. . . Mesh part,

Claims (3)

The conductor circuit is formed on the surface of the substrate, then, a method for manufacturing a printed wiring board covering the insulating layer on the surface of the substrate including the conductor circuit,
After forming the blackening layer to the conductor circuit surface, the surface of the substrate, between adjacent said conductor circuit, a write-free process to fill the potting,
Applying a first insulating resin as a surface treatment material for protecting the blackening layer to the entire surface of the embedding resin and the conductor circuit to form a first insulating resin layer ;
Applying a second insulating resin obtained by adding a silica filler to the component of the first insulating resin to the surface of the first insulating resin layer to form a second insulating resin layer ;
Applying a third insulating resin obtained by adding an epoxy resin filler to the component of the first insulating resin to the surface of the second insulating resin layer to form a third insulating resin layer; ,
The printed wiring board manufacturing method characterized by including this. 2. The printed wiring according to claim 1 , wherein the embedding resin is embedded by screen printing, and the screen printing uses a screen having a mesh portion narrower than between adjacent conductor circuits. A manufacturing method of a board. After forming the insulating layer, a via hole is formed in the insulating layer, and then the inner wall of the via hole and the surface of the insulating layer are roughened by immersing in a roughening solution, and then metal plating is performed. the conductor layer on the inner wall of the via hole, also in forming a conductor circuit on a surface of the insulating layer, according to claim 1, wherein the potting compound is characterized by having a property of dissolving the roughening solution, or The manufacturing method of the printed wiring board of 2 .

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