JP2001118950A - Method for manufacturing built-up multi-layered board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a built-up multi-layered board using a resin material roughened with chromic acid, which is excellent in its via connection reliability. SOLUTION: In the method for manufacturing a built-up multi-layered board, a surface of a resin board is roughened with chromic acid, a chromate film formed on a wiring surface of a via bottom is removed, a via connection strength is increased to build up multiple substrates into a multi-layered board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an I / O
The present invention relates to a method for manufacturing a multilayer printed circuit board for mounting a C package, an MCM, and an electronic component.

[0002]

2. Description of the Related Art In recent years, high-frequency driving of MPUs has rapidly progressed, and the package structure has been W / B type PGA (Pin).
From Grid Array) to Flip Chip BGA (B
all Grid Array), and a low-dielectric resin material and Cu-plated wiring, which are advantageous in increasing the frequency of the package material. IC packages will be made of resin materials /
It is expected that there will be a rapid shift to flip chip BGA using Cu wiring. Under these circumstances, a built-up substrate has recently been receiving attention. A built-up multilayer board using a printed board as a core board, a resin material as an interlayer insulating material, and Cu plating for wiring formation has attracted attention as an IC package for mounting an MPU, an MCM, and a high-density mounting board for mounting electronic components. The development is being vigorously pursued by printed circuit board manufacturers, IC package manufacturers, semiconductor manufacturers, and the like.

In the manufacturing process of a built-up substrate, the resin surface is partially dissolved with an appropriate oxidizing agent to form irregularities on the resin surface in order to secure the adhesion reliability between the resin used for the interlayer insulating layer and the Cu conductor. Roughening processing (desmear processing) is usually performed. As the oxidizing agent, KMnO ₄ or C
rO ₃ is commonly used.

Here, in a resin using CrO ₃ for the roughening treatment, a chromate film of CrO ₃ is formed on the Cu surface which becomes the via connection interface together with the roughening of the resin surface. Even if plating is performed on Cu on which a chromate film has been formed, metal-to-metal bonding cannot be performed, so that the adhesive strength of the plating layer is significantly reduced. This must not be the case for the interlayer connection of the multilayer circuit board. Therefore, at present, when performing roughening treatment on CrO ₃ , needle-like plating is performed on the wiring surface at the bottom of the via in order to suppress a decrease in via connection strength. The needle height of this needle plating is 2-3μ
m, but still only about half the connection strength in the case of the roughening treatment using KMnO ₄ . Also,
As the miniaturization of wiring progresses, in the needle-shaped plating,
A short circuit occurs in a dense wiring, and it cannot be used.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a built-up multilayer board using a resin material subjected to a roughening treatment with chromic acid and having excellent via connection reliability.

[0006]

According to the present invention, a surface of a resin substrate is roughened with chromic acid, and a chromate film formed on a wiring surface at the bottom of a via is removed.
A method for manufacturing a built-up multilayer substrate, characterized in that a via connection strength is increased to build up a substrate in multiple layers.

In the method of manufacturing a built-up multilayer substrate to which the present invention is applied, a circuit forming method can be any of a subtractive, semi-additive and full-additive method. Here, the semi-additive method will be described. It consists of the following steps.

(1) A Cu conductor circuit 2 is formed on a substrate 1. Chemical Cu plating 3 is performed, and pattern electrolytic Cu plating 4 is performed using a photosensitive plating resist. After removing the plating resist, the chemical Cu film between the wirings is removed by etching to form a circuit (see FIG. 1).

(2) The surface of the formed Cu circuit conductor is subjected to a surface roughening treatment 5 such as an etching process or a needle-like process (the completion of the Cu conductor circuit on the core substrate). A metal protective film for chromic acid may be formed (see FIG. 2).

(3) Next, a built-up insulating resin 6 is formed. The resin forming method may be any method of applying a liquid resin or laminating a resin sheet (see FIG. 3).

(4) A via hole 7 for interlayer connection is formed at a predetermined position of the insulating resin 6. Either a photo via method using a photosensitive resin or a laser via method using a thermosetting resin may be used (see FIG. 4).

(5) The resin surface 6 is roughened with chromic acid. At this time, a chromate film 8 is formed on the metal surface at the bottom of the via hole 7 (see FIG. 5).

(6) The chromate film 8 is removed. Plasma ashing and sodium gluconate can be considered as the treatment for removing the chromate film. Further, an etchant for dissolving the metal on which the chromate film has been formed can also be used. For example, in the case of Cu, an etching solution of sodium persulfate / sulfuric acid and hydrogen peroxide / sulfuric acid can be considered (see FIG. 6).

(7) Chemical plating 9 is applied to the resin surface 6 roughened with chromic acid (see FIG. 7).

(8) A Cu conductor circuit is formed in the same manner as in the above (2).

(9) The surface of the formed Cu circuit conductor is subjected to a surface roughening treatment such as an etching treatment or a surface roughening treatment such as a needle shape. A metal protective film for chromic acid may be formed (the second-layer Cu conductor circuit is completed).

After (10), if the build-up is to be continued, the above steps (4) to (9) are repeated.

According to the present invention, the surface of the resin substrate is roughened with chromic acid to ensure the reliability of adhesion between the interlayer insulating resin and the conductor, and at the same time, the chromate film formed on the metal surface at the bottom of the via hole By removing, the metal-to-metal coupling on the surface can be ensured and the via connection reliability can be improved.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described based on examples of the present invention and comparative examples.

Table 1 shows the processing contents of each example. In order to roughen the surface of the Cu wiring by etching, a CZ treatment of Mec was applied. In addition, Copper Glyme ST-901 manufactured by Relonal was used as an additive for electrolytic Cu plating of the wiring. When this plating solution is used, a chromate film is formed against chromic acid to have corrosion resistance.

[0021]

[Table 1]

In Example 1, sodium persulfate 100 g / L +
An etching solution of 50 ml / L of sulfuric acid was used by immersion for 2 minutes at room temperature. In Example 2, a hydrogen peroxide-sulfuric acid-based etching solution Metex G-5S manufactured by McDermitt Japan was used for 42 times.
It was used by immersion at 30 ° C. for 30 seconds. In Example 3, treatment was performed by immersing a 5% sodium gluconate + 10% NaOH solution at 35 ° C. for 5 minutes. In the fourth embodiment, the O ₂ plasma (4000
W, 250 mTorr, O ₂ gas, processing time 3 minutes) to remove the chromate film. In Comparative Example 1, no chromate was removed. Comparative Example 2 is a process in which permanganic acid is used, so that no chromate film is formed.

Table 2 shows the via shear strength of the package subjected to the processing of Table 1. The via shear was performed after removing the resin as an insulating layer by O ₂ plasma ashing to expose the via. As the destruction mode, L indicates that the via peeled off from the bonding interface, and W indicates that the via deformed due to shear without separating from the bonding interface. Those indicated as W are predicted to have higher interface strength than the displayed strength.

[0024]

[Table 2]

In Comparative Example 1, the chromate film was not removed. At this time, the shear strength was 0 g, which could not be measured in most vias. It is in a state where it comes off when touched. In Comparative Example 2, the resin was roughened by the permanganic acid treatment, and thus no chromate film was formed. The shear strength is large, and all the destruction modes are W. Only the via is deformed, and there is no peeling at the via connection portion. From Comparative Examples 1 and 2, it is clear that the chromate film obtained by the chromic acid treatment greatly affects the via connection strength. Examples 1 to 4 have the same strength as Comparative Example 2 due to chromate removal. The via is only deformed, and no peeling at the via connection portion is observed. It is recognized that the chromate film was completely removed.

[0026]

According to the present invention, the roughening treatment with chromic acid ensures the metal bonding at the joint surface between the multilayer substrates and the via connection interface, and increases the via connection strength.
A manufacturing method that enables via connection with excellent reliability and that can be easily realized is obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram up to the formation of a circuit.

FIG. 2 is an explanatory diagram of a roughening treatment of a circuit conductor surface.

FIG. 3 is an explanatory diagram of formation of an insulating resin.

FIG. 4 is an explanatory diagram of via hole formation.

FIG. 5 is an enlarged view of a via hole and is an explanatory diagram of a roughening process.

FIG. 6 is an explanatory diagram of chromate film removal.

FIG. 7 is an explanatory diagram of a chemical plating process.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 Cu conductor circuit 3 chemical Cu plating 4 electrolytic Cu plating 5 surface roughening treatment 6 insulating resin 7 via hole 8 chromate film 9 chemical plating treatment

Claims (2)

[Claims] 1. A surface of a resin substrate is roughened with chromic acid, and a process of removing a chromate film formed on a wiring surface at a bottom portion of a via is performed to increase a via connection strength and build up a multilayer substrate. A method for manufacturing a built-up multilayer substrate, characterized by comprising: 2. The method for manufacturing a built-up multilayer substrate according to claim 1, wherein the process for removing the chromate film is etching or plasma ashing.