JP2007203681A - Method for treating surface of copper layer, laminate including treated copper layer, and wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating the surface of a copper layer which can ensure a sufficient grab in combining the copper layer and a resin insulating layer in one piece. <P>SOLUTION: The surface of the copper layer is given a blackening treatment, and further, the treated surface is given a coupling agent treatment. In this respect, a reduction treatment is preferably performed following the blackening treatment, and further, the coupling agent treatment is applied to the surface to be treated. This treatment method is, for example, applied to a rolled copper foil with not less than 100 μm thickness, then the treated surface of the copper foil is superposed on a prepreg layer, and both copper foil and prepreg layer are thermally pressurized in one piece into a laminate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface treatment method for a copper layer. Moreover, it is related with the laminated board and wiring board containing the copper layer which performed the said process. The wiring board is suitable for applications in which a large current is passed.

  A wiring board mounted on an electronic device is required to have a technology for fine wiring and high-density mounting in accordance with a reduction in the thickness and size of the electronic device, and a technology for high heat dissipation corresponding to heat generation is also required. In particular, in electronic circuits such as automobiles that use a large current for various controls and operations, heat generation due to the resistance of the conductive circuit and heat generation from the power element are very large, and the heat dissipation characteristics of the wiring board may be high. It has become essential. As a countermeasure, it has been proposed to increase the thermal conductivity by increasing the copper layer constituting the conductive circuit of the wiring board and to promote heat dissipation.

In the production of the wiring board, a laminated board in which a copper layer is integrated with a resin insulating layer by heating and pressing is used, and the copper layer of the laminated board is processed into a conductive circuit to form a wiring board. Usually, the copper layer is selected from electrolytic copper foil or rolled copper foil, but if a thin copper layer is acceptable, electrolytic copper foil by electrodeposition is selected, and a thick copper layer that is difficult to manufacture by electrodeposition is required. In this case, a rolled copper foil is selected.
Since one surface of the electrolytic copper foil is a rough surface generated as a result of electrodeposition, the heat treatment is performed by contacting the rough surface with the resin insulating layer, and the convex portions constituting the rough surface are made of resin. The insulating layer is bitten and the anchoring effect increases the adhesion between the resin insulating layer and the copper layer. On the other hand, since the rolled copper foil is a smooth surface on both sides in the manufacturing process, in integrating the copper layer into the resin insulation layer, the contact surface of the copper layer to the resin insulation layer is A separate roughening treatment is required.

  Common roughening treatment methods for copper layers include blackening treatment and blackening reduction treatment, but sufficient heat resistance in the integration of copper layer and resin insulation layer (copper layer and resin insulation even after heat treatment) It is known that it is not possible to ensure properties that do not reduce the adhesion of the layers. Moreover, as a roughening method of the rolled copper foil, there is a method (for example, Patent Document 1) in which fine particles collide with the surface of the copper layer at high speed to give fine irregularities on the surface. However, even with such a treated copper layer, sufficient adhesion and heat resistance with the resin insulating layer have not been secured.

JP 2002-79466 A

  The problem to be solved by the present invention is to provide a surface treatment method of a copper layer that can secure a sufficient adhesion force when the copper layer and the resin insulating layer are integrated. Moreover, it is providing the laminated board and wiring board which integrated the copper layer and resin insulating layer which processed the said process.

  The surface treatment method for the copper layer is preferably applied to a rolled copper foil having a smooth surface, and aims to ensure adhesion between the copper layer and the insulating resin layer.

In order to achieve the above object, a surface treatment method for a copper layer according to the present invention is characterized in that the surface of the copper layer is subjected to blackening treatment, and further, the treatment surface is subjected to coupling agent treatment (claim) 1). In the above, preferably, after the blackening treatment, reduction treatment is performed, and further, the treatment surface is subjected to a coupling agent treatment (claim 2).
The copper layer is, for example, a rolled copper foil having a thickness of 100 μm or more (Claim 3).

  Here, the blackening treatment is an operation of generating fine acicular cuprous oxide or cupric oxide on the surface of the copper layer. The reduction process is an operation for reducing the blackening process.

  The surface of the copper layer surface-treated by the method according to the present invention is provided with blackening treatment, preferably fine unevenness of submicron order by blackening treatment and reduction treatment, and a coupling agent treatment is performed thereon. It becomes a form. As a result, the copper layer exhibits fine surface properties, and the surface has a chemical bonding force.

A laminated board in which a copper layer having the above surface property is integrated by heat and pressure molding with its treated surface in contact with the resin insulating layer is cast on the resin insulating layer due to the fine surface property of the copper layer. In addition to the effect, chemical bond strength is also added.
In addition, since the chemical resistance with respect to the plating solution etc. of a copper layer improves, it is more preferable to perform a blackening process and a reduction process rather than only a blackening process.

  According to the surface treatment method for a copper layer according to the present invention (Claims 1 and 2), in addition to the fine irregularities formed on the copper layer, a chemical bonding force can be imparted. In the laminated board (Claim 4) integrated with the insulating layer by heating and pressing (Claim 4) and the wiring board (Claim 5) processed from this, due to the anchoring effect of the copper layer on the resin insulating layer and the chemical bond The adhesion between the copper layer and the resin insulating layer can be made excellent. As a result, the laminated board and the wiring board can also improve the characteristic (hereinafter referred to as “heat resistance”) that does not reduce the adhesion between the copper layer and the resin insulating layer even after the heat treatment.

  A copper layer having a thickness of 100 μm or more becomes increasingly difficult to produce by the electrodeposition method, and is produced by rolling. In this case, since the surface of the copper layer is smooth and has no irregularities, a high adhesion between the copper layer and the resin insulating layer is ensured if the surface treatment is performed by the method according to claim 3 and the laminate is manufactured. Convenient to. This contributes to the provision of a wiring board having a thick conductive circuit, and the reliability is improved by applying it to a wiring board for automobile equipment and large machines through which a large current flows. Since the conductive circuit is thick, heat dissipation is good.

  An embodiment of the invention will be described for the case of using a rolled copper foil as the copper layer. The rolled copper foil usually has a thickness of 100 μm or more.

  First, blackening treatment, preferably blackening treatment and reduction treatment, is performed on the rolled copper foil to form submicron irregularities on the surface of the copper foil. Thereby, a fine surface texture is exhibited. For the blackening treatment, a roughening solution mainly composed of an aqueous sodium chlorite solution can be used, and this treatment produces fine acicular cuprous oxide or cupric oxide on the copper foil surface. Let In the subsequent reduction treatment, both organic and inorganic reducing agents can be used. By this treatment, the cuprous oxide or cupric oxide is reduced to copper. For the blackening treatment and the reduction treatment, treatments generally used in the manufacturing process of the multilayer printed wiring board can be applied.

  After the blackening treatment, preferably after the blackening treatment and the reduction treatment, the coupling agent treatment is performed. The coupling agent is a silane coupling agent or a titanate coupling agent.

  The treated surface of the rolled copper foil subjected to the above treatment is brought into contact with the resin insulating layer and integrated by heating and pressing to obtain a laminated plate. The resin insulation layer does not include a prepreg or a sheet-like fiber base material that is semi-cured by impregnating a sheet-like fiber base material (a woven or non-woven fabric of inorganic or organic fibers) with a thermosetting resin such as an epoxy resin. It is a resin insulating layer (BT resin or the like). In the prepreg, the resin is cured by heating and pressing to form a resin insulating layer. A metal oxide or hydroxide, inorganic ceramics, and other fillers can be blended in the resin insulating layer. Even when such a filler is blended, good adhesion between the copper layer and the resin insulating layer can be secured.

  The laminated plate may be integrated with the ceramic substrate via a resin insulating layer. The laminated board becomes a wiring board by processing the copper layer into a conductor circuit, and the treatment method according to the present invention is applied to the surface of the conductor circuit, and the copper layer is integrated on the resin insulating layer thereon. And a multilayer wiring board configuration can be obtained.

  Hereinafter, examples according to the present invention will be described in detail together with comparative examples. In addition, this invention is not limited to a present Example, unless it deviates from the summary.

Example 1
Blackening treatment was performed on a rolled copper foil (JIS C1201P) having a thickness of 100 μm in the order of degreasing treatment, acid treatment, and oxidation treatment. At this time, sulfuric acid was used for the acid treatment, and a mixed aqueous solution of sodium chlorite, sodium phosphate, and sodium hydroxide was used for the oxidation treatment. After drying through a blackening treatment, a treatment of immersing in an aqueous solution of a silane coupling agent was performed.
On the treated surface of the rolled copper foil subjected to the above surface treatment, a layer composed of five high heat-resistant FR-4 grade prepregs is layered and formed by heating and pressing for 90 minutes at a temperature of 175 ° C. and a pressure of 4 MPa. A laminated plate having a thickness of 1.2 mm was obtained.

Example 2
In Example 1, reduction treatment was performed after degreasing treatment, acid treatment, and oxidation treatment. For the reduction treatment, a mixed aqueous solution of dimethylaminoborane and sodium hydroxide was used. After drying through a blackening reduction treatment, a treatment of immersing in an aqueous solution of a silane coupling agent was further performed.
Thereafter, similarly to Example 1, a laminated plate having a thickness of 1.2 mm was obtained.

Comparative Example 1
In Example 1, the rolled copper foil was used untreated without performing the blackening treatment and the coupling agent treatment, and thereafter, a laminated plate having a thickness of 1.2 mm was obtained in the same manner as in Example 1.

Comparative Example 2
In Example 1, only the coupling agent treatment was performed without performing the blackening treatment. Thereafter, similarly to Example 1, a laminated plate having a thickness of 1.2 mm was obtained.

Comparative Example 3
In Example 2, only the blackening treatment and the reduction treatment were performed without performing the coupling agent treatment. Thereafter, similarly to Example 1, a laminated plate having a thickness of 1.2 mm was obtained.

Comparative Example 4
A surface of a rolled copper foil (JIS C1201P) having a thickness of 100 μm was subjected to blasting using a suction type air blasting device using air pressure. This is a process of spraying particles mainly composed of alumina having an average particle diameter of 70 μm on the surface of the copper foil at a discharge pressure of 0.4 MPa for 40 seconds.
The rolled copper foil which performed said roughening process was used, and the laminated board of thickness 1.2mm was obtained similarly to Example 1 after that.

Comparative Example 5
The rolled copper foil which performed the roughening process of the comparative example 4 was used, and also the process immersed in the aqueous solution of a silane coupling agent was performed. Thereafter, similarly to Example 1, a laminated plate having a thickness of 1.2 mm was obtained.

About the laminated board produced in each said example, copper foil peeling strength and plating solution resistance were evaluated. The results are shown in Table 1. The measuring method is as follows.
Copper foil peel strength: A 25 mm × 100 mm test piece was cut out from the laminate, and the copper foil peel strength after aging at 177 ° C. for 240 hours was measured at room temperature using a shopper. The copper foil peel strength in the normal state was shown as a relative index with reference to Example 1. Moreover, the peeling strength after aging was indicated as ◯ when the retention ratio with respect to the peeling strength in a normal state was 20% or more and less than 50%, and × when less than 20%.
Resistance to plating solution: A 0.6 mm hole was made in the laminated plates of Examples 1 and 2 and Comparative Example 3, and after immersion in an 18% HCl aqueous solution for 3 hours, the presence or absence of discoloration (haloing) was confirmed. The plating solution properties were evaluated. Those without discoloration were indicated as ◯, and those with discoloration as ×.

  As is clear from the above table, the laminated board in which the copper layer treated by the method according to the present invention is integrated with the resin insulating layer by heat and pressure molding has good peel strength in a normal state and good heat resistance. Can be understood (contrast of Example and Comparative Example). From the above comparative example, it can be understood that the peeling strength and heat resistance are low in the coupling agent, blackening reduction treatment, and blast treatment. Further, it can be understood that when the reduction treatment is added to the blackening treatment, the plating solution resistance of the copper layer is improved (contrast between Example 2 and Example 1).

Claims (5)

  A surface treatment method for a copper layer, wherein the surface of the copper layer is subjected to blackening treatment, and the treatment surface is further treated with a coupling agent.   2. The surface treatment method for a copper layer according to claim 1, wherein a reduction treatment of the treated surface is performed between the blackening treatment and the coupling agent treatment.   The copper layer surface treatment method according to claim 1, wherein the copper layer is a rolled copper foil having a thickness of 100 μm or more.   The laminated board which integrated the process surface into the resin insulating layer by heat-press molding using the copper layer processed by the method in any one of Claims 1-3.   The wiring board by which the copper layer of the laminated board of Claim 4 was processed into the conductive circuit.