JPH11346058A - Multi-layer wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish both the connection reliability of a non-penetration connection hole with a small diameter and the insulation reliability between inner-layer and outer-layer circuit conductors, by making thick the thickness of the inner-layer circuit conductor of a part for forming the non-penetration connection hole as compared with that of other inner-layer circuit conductors, and by making thin the insulation layer of the part for forming the non-penetration connection hole. SOLUTION: The thickness of an inner-layer circuit conductor 5 of a part for forming a non-penetration connection hole (IVH) is thickened as compared with that of an inner-layer circuit conductor 6 of other parts, thus making thin the thickness of an insulation layer 7 of the part for forming the IVH as compared with the insulation layer 7 for covering other parts of the inner-layer circuit conductor. Therefore, when a non-penetration hole 9 is punched at the part of forming the IVH, a small aspect ratio and a superior punching property can be achieved since the thickness of the insulation layer 7 of the part is thin. Also, an absolutely electroless plating layer can be formed in the hole with a small diameter, thus simultaneously achieving the connection reliability of an IVH 19 with the small diameter of a multi-layer wiring board and the insulation reliability between the inner-layer circuit conductor 6 and an outer-layer circuit conductor 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board having non-through connection holes and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, a method of manufacturing a multilayer wiring board having a non-through connection hole includes a method of forming by a subtractive method, a method of forming by an additive method, and a method of forming by a photo via method. When non-through connection holes are formed between the inner layer circuit conductors and between the inner layer circuit conductor and the outer layer circuit conductor, the aspect ratio is one of the major factors that affect the difficulty of manufacturing the non-through connection holes and the connection reliability. (Thickness of the material to be drilled / diameter of the hole). This is because as the aspect ratio increases, it becomes more difficult to completely infiltrate the processing liquid for processing the hole in the hole and the inside of the hole by the wet processing method. Conventionally, non-through hole diameter φ
0.2 mm or less, when the thickness of the insulating layer is less than 200 μm, the angle between the upper end of the non-through hole and the wall surface of the hole as 90 to 110 degrees as a method of drilling the non-through connection hole by laser and photographic method. The above problem is addressed as the shape of the inverted tapered hole to be formed.

FIG. 2 shows a case where a small diameter non-penetrating connection hole having a diameter of 100 μm or less for laser processing is formed.
A description will be given based on a simplified embodiment of the invention. First, in FIG. 2 (a), the inner-layer circuit conductor 5 in a portion where a non-through connection hole is formed is formed on a single-sided glass epoxy copper-clad laminate 1 having a copper foil thickness of 18 μm.
And an inner layer circuit conductor 6 other than the non-through connection hole forming portion, an insulating layer 7 is formed on the inner layer circuit conductor so that the thickness of the conductor is 50 μm, and an adhesive is further formed thereon. After forming the layer 8 to a thickness of 20 μm, laser processing is performed to form a non-through hole having a diameter of 70 μm. Next, a plating resist 12 is formed at a desired position on the adhesive layer 8, and electroless copper plating is performed to form an outer layer circuit conductor 16 and a non-through connection hole 19. Then, the total thickness of the insulating layer 7 and the adhesive layer 8 on the inner circuit conductor at the time of completion is about 70 μm. Accordingly, since the hole having a diameter of 70 μm is formed in the insulating material having a thickness of 70 μm, the aspect ratio is 1.0.

In FIG. 2B, the insulating layer 7 formed on the inner circuit conductors 5 and 6 is made to have a thickness of 15 μm on the conductor, and the thickness of the adhesive layer 8 is set to 20 μm for a total thickness of 35 μm. When a non-through connection hole 19 having an aspect ratio of 0.5 is formed when a non-through hole diameter of 70 μm is drilled after that, the non-through connection hole 19 in FIG. The connection reliability between the inner layer circuit conductor 5 and the outer layer circuit conductor in the hole forming portion is poor, and the connection reliability of the non-through connection hole 19 in FIG. Although the connection reliability between the conductor 5 and the outer layer circuit conductor is good, the other inner layer circuit conductor 6 and the outer layer circuit conductor 16
Since the total thickness of the insulating layer 7 and the adhesive layer 8 is reduced to 35 μm, the insulation reliability between the inner circuit and the outer circuit deteriorates.

[0005]

In general, the conduction reliability of this type of multilayer wiring board largely depends on the reliability of a non-through connection hole (hereinafter referred to as IVH) connecting each layer. Therefore, in order to form a small-diameter IVH without lowering the connection reliability of the IVH, the thickness of the insulating layer can be reduced as the hole diameter is reduced so as not to increase the aspect ratio. As described above, the insulation property is reduced, and the insulation reliability is deteriorated. Further, as described in the related art, the angle formed by the upper edge of the IVH and the wall surface of the hole is 90 degrees to 1 degree.
In the method of drilling a non-through hole having an inverted tapered hole shape formed at 10 degrees, work management is complicated and workability is deteriorated, and the cost is high because a special insulating layer composed of a plurality of layers is used.

[0006]

According to the present invention, in order to solve the above-mentioned problems, the thickness of the inner layer circuit conductor in the portion where the IVH is formed is made larger than the thickness of the inner layer circuit conductor other than the portion where the IVH is formed. As a result, the aspect ratio of the non-through hole processing is reduced by reducing the thickness of the insulating layer in the IVH formation portion,
By setting the thickness of the insulating layer on the inner layer circuit conductor other than the H-formed portion to a normal thickness, the insulation between the inner layer circuit conductor other than the IVH-formed portion and the outer layer circuit conductor is prevented from lowering, and the insulation is prevented. This is to ensure reliability.

In a multilayer wiring board having a non-through connection hole (IVH), the thickness of the inner layer circuit conductor at the portion where the non-through connection hole is formed is larger than the thickness of other inner layer circuit conductors other than the portion where the non-through connection hole is formed. A multi-layer wiring board which is thick and has a thickness of the insulating layer on the inner layer circuit conductor at a portion where the non-through connection hole is formed is smaller than the thickness of the insulating layer covering the other inner layer circuit conductors.

An inner layer circuit conductor is formed on a substrate, an insulating layer is formed on the inner layer circuit conductor, a non-through hole is formed in the insulating layer by a laser, and the non-through hole is formed by plating. In the method for manufacturing a multilayer wiring board connecting the inner layer circuit conductor and the outer layer circuit conductor, a step of forming the thickness of the inner layer circuit conductor at a portion where a non-through connection hole is formed to be larger than the thickness of the other inner layer circuit conductors, Forming the thickness of the insulating layer on the inner circuit conductor in the portion forming the non-through connection hole smaller than the thickness of the insulating layer covering the other inner circuit conductors. This is a method for manufacturing a multilayer wiring board that enables a small-diameter IVH to be easily formed by reducing the size.

[0009]

FIG. 1 is a block diagram showing an embodiment of the present invention.
It will be described based on. FIG. 1 is a sectional view of a multilayer wiring board for explaining a manufacturing process according to the present invention. FIG. 1 (a)
, A glass epoxy copper-clad laminate denoted by reference numeral 1 uses MCL-E-168 (trade name, manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 18 μm of copper foil 1A on the upper and lower surfaces. A masking film is formed on the copper foil 1A of the base material by using a resist 2 for pattern plating (trade name: H-U340 of Hitachi Chemical Co., Ltd.) except for the pattern portion where the IVH is to be formed. By performing the pattern plating 3 of the IVH forming portion with the thickness, the thickness of the inner layer circuit conductor in the portion where the IVH is formed is increased. This time, the inner layer circuit conductor is manufactured with the electrolytic plating thickness of 35 μm.

Next, as shown in FIG. 1 (b), the inner layer circuit conductors 5 and I at the desired IVH forming portion in the etching process are formed.
The inner layer circuit conductors 6 in other portions other than the VH forming portion are formed. The thickness of the inner layer circuit conductor 5 in the IVH formation portion is I
It becomes thicker by the thickness of the electrolytic plating than the inner layer circuit conductor 6 other than the VH forming portion. That is, an inner-layer circuit conductor having two types of conductor thickness is formed. After forming the inner layer circuit conductors 5 and 6, the trade name H of Hitachi Chemical Polymer Co., Ltd.
The insulating layer 7 is formed by a screen printing method so as to have a thickness of 55 to 70 μm on the inner layer circuit conductor 6 other than the portion where the IVH is formed by R-3 and dried. Then, the uneven surface of the insulating layer 7 is polished so as to be smooth, and the thickness of the insulating layer is set to approximately 50 μm on the inner layer circuit conductor 6 other than the polished IVH forming portion. Further, in order to strengthen the adhesive force between the insulating layer 7 and the outer layer circuit conductor, an adhesive layer 8 was formed on the insulating layer 7 by a curtain coater method using a trade name HA-22 of Hitachi Chemical Co., Ltd. Formed with a thickness of The materials used for the insulating layer 7 and the adhesive layer 8 are not limited to the above materials,
An insulating material such as an ink, a film, or a flexible plate may be used. Further, the method of forming the coating includes a screen printing method, a dipping method, a curtain coater method, a roll coater method, a laminator method, a photographic method, a thermocompression bonding method, and the like.

Next, as shown in FIG. 1 (c), a diameter of 70 .mu.m which penetrates the adhesive layer 8 and the insulating layer 7 from above the adhesive layer 8 by laser processing and reaches the inner layer circuit conductor 5 in the IVH forming portion. Is formed. The non-through hole 9 formed by recessing the adhesive layer 8 and the insulating layer 7 by laser can be up to 40 μm in diameter. Thereafter, as shown in FIG. 1 (d), a smear treatment was performed at 950 g / l of chromic anhydride at 38 ° C. for 18 minutes, and the product name was HS (trade name) of Hitachi Chemical Co., Ltd.
-101B after cedar treatment, Hitachi Chemical Co., Ltd. S
The plating resist 12 is formed on the adhesive layer 8 with R-3000.
To form Then, sodium fluoride 10g / l,
After roughening with a solution of chromic acid 15 g / l and sulfuric acid 400 ml / l, a trade name CC-41 of Hitachi AC Co., Ltd.
Electroless copper plating is performed by an electroless copper plating method to form an IVH (non-through connection hole) 12 and an outer layer circuit conductor 16.

As described above, by making the thickness of the inner layer circuit conductor 5 in the portion where the IVH is formed larger than the thickness of the other inner layer circuit conductors 6 other than the portion where the IVH is formed,
Can be made thinner than the thickness of the insulating layer 7 covering the inner layer circuit conductor other than the IVH forming portion. Therefore, when the non-through hole 9 is drilled in the portion where the IVH is to be formed, the thickness of the insulating layer 7 in this portion is small, so that the aspect ratio is small and drilling workability is improved,
In addition, the permeability of the treatment liquid into the holes during the wet processing in the small-diameter holes is improved, and a complete electroless copper plating layer can be formed.

Table 1 shows the specifications of the IVH 19 of the multilayer wiring board of the present embodiment formed as described above, and the general insulating layer 7 and adhesive layer 8 shown in FIG. 2A. As shown in FIG. 2 (b), the IVH 19 of the multilayer wiring board is taken as Comparative Example 1, and as shown in FIG. In this example, the connection reliability of the IVH and the insulation reliability between the inner layer circuit conductor and the outer layer circuit conductor were compared using the IVH19 of the multilayer wiring board substantially the same as the multilayer wiring board of Comparative Example 2 as Comparative Example 2. As is apparent from Table 1, the small-diameter IVH19 of the multilayer wiring board of the present invention is used.
And the insulation reliability between the inner layer circuit conductor 6 and the outer layer circuit conductor 16 can be compatible.

[0014]

[Table 1] Characteristics comparison results Number of samples = 50 * 1: MIL-STD-202E is a multilayer board on which the sample D of JIS-C5012 composite test pattern for multilayer printed board is formed as shown in Appendix 2.1, Appendix 2.2, and Appendix 2.7.
07D thermal shock test 1000 cycles, quality standard MI
IV after 1000 cycles with LP-55110C
Samples that exceeded 10% of the initial resistance value of H were rejected. * 2: Same as above JIS standard multi-layer printed circuit board composite test pattern Multi-layer board with sample M shown in Attached Figure 2.1 and Attached Figure 2.4, processed at 85 ° C, 85% RH and applied voltage of 100V DC for 2,000 hours After that, the insulation resistance value of 10 ⁷ Ω or more was judged to be acceptable.

[0015]

As described above, according to the present invention,
When forming the small-diameter IVH, the upper edge of the IVH and the wall surface of the hole do not have an inverted tapered hole shape, and the thickness of the inner layer circuit conductor at the portion where the IVH is formed is changed to another inner layer other than the IVH forming portion. When the thickness of the circuit conductor is made larger than the thickness of the circuit conductor and the surface of the insulating layer is made smooth, only the insulating layer in the portion where the IVH is formed can be made thinner than the insulating layer covering the other inner layer circuit conductors. Is low. Therefore, the small-diameter IVH of the present invention has connection reliability and
The insulation reliability between the inner layer circuit conductor and the outer layer circuit conductor can be compatible.

[Brief description of the drawings]

FIG. 1 is a sectional view of a multilayer wiring board for explaining a manufacturing process of the present invention.

FIG. 2 is a cross-sectional view of a multilayer wiring board for explaining a case where a small-diameter non-through connection hole is formed.

[Explanation of symbols]

1. Copper-laminated laminate 2. Resist for pattern plating 3.
Pattern plating 5 ... Inner layer circuit conductor in IVH forming part 6 ... Inner layer circuit conductor in other part 7 ... Insulating layer 8 ... Adhesive layer 9 ... Non-through hole 12 ... Plating resist 16 ... Outer layer circuit conductor 19 ... IVH (non-through connection) hole). Reference number P2452

Continuing from the front page (72) Inventor Yasuhiro Iwasaki 1065 Kushita, Ninomiya-cho, Haga-gun, Tochigi Prefecture Within Hitachi AIC Co., Ltd.

Claims (2)

[Claims] In a multilayer wiring board having a non-through connection hole, a thickness of an inner layer circuit conductor at a portion where the non-through connection hole is formed is larger than a thickness of another inner layer circuit conductor, and the non-through connection hole is formed. A multilayer wiring board, wherein the thickness of an insulating layer in a portion to be formed is smaller than the thickness of an insulating layer covering another inner layer circuit conductor. 2. A method for manufacturing a multilayer wiring board for connecting an inner layer circuit conductor and an outer layer circuit conductor via a non-through connection hole, wherein the thickness of the inner layer circuit conductor at a portion where the non-through connection hole is formed is changed to another inner layer. A step of making the circuit conductor thicker than the thickness of the circuit conductor, and a step of forming the part of the insulating layer where the non-through connection hole is formed to be thinner than the thickness of the insulating layer covering the other inner layer circuit conductors. Of manufacturing a multilayer wiring board.