JP2003258182A - Method for roughening metal foil and roughened metal foil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roughening method for performing a stable processing in thin foil of not larger than 10 μm, copper foil and copper alloy foil of not smaller than 100 μm and 42 alloy used for a lead frame. <P>SOLUTION: In the roughening method of metal foil, metal foil is irradiated with a laser beam to unevenness of 0.5 to 10 μm, whose surface roughness is 10 point average roughness, is formed. The roughened metal foil is obtained by the roughening method mentioned. A rust prevention layer is disposed on the surface of metal foil and has a coupling agent processing layer on the surface. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for roughening a metal foil, which is characterized by forming irregularities having a surface roughness of 10 to 10 μm in average roughness of 0.5 to 10 μm and a method for producing the same. It relates to a roughened metal foil.

[0002]

2. Description of the Related Art In a composite of a metal foil and a resin widely used in the electronic industry, the adhesive strength at the interface is extremely important for ensuring reliability. For example, in a copper foil used for a printed wiring board, in order to prevent the fine copper wiring from falling off the base resin, fine copper particles called roughening particles are formed on the copper foil surface to form a copper foil. It improves the adhesion between the foil and the base resin. The formation of roughened particles is
Usually, it is carried out by immersing a copper foil in an aqueous solution of copper sulfate and depositing copper by electrolysis. In a semiconductor package, the surface of the lead frame is roughened in order to prevent external air from entering the interface between the lead frame and the sealant resin and deteriorating the semiconductor element. As the lead frame, in addition to 42 alloy which is an alloy of nickel and iron, various rolled copper alloys have been used in recent years. Roughening is generally performed by etching, but attempts have also been made to form various metal particles.

[0003]

In the conventional roughening method using an aqueous solution of copper sulfate, it is necessary to perform complicated multi-step treatments in order to achieve a predetermined roughened shape, and the thickness is 10 or less.
The copper foil having a thickness of less than μm has a problem that wrinkles are likely to occur. Further, since the roughened particles are relatively large and have different heights, it is difficult to completely remove the roughened particles that have entered the base resin by etching. On the other hand, in a printed wiring board used for power control or heat dissipation, a copper foil or a copper alloy foil having a thickness of 100 μm or more is used. There is a difficult problem. Similarly, it is difficult for the lead frame to stably pass through the treatment tank and perform a predetermined treatment.

That is, the present invention provides a roughening method for performing stable treatment even on thin foils of 10 μm or less, copper foils and copper alloy foils of 100 μm or more, and 42 alloy used for lead frames. The present invention also provides a metal foil produced by the roughening method.

[0005]

According to the present invention, a metal foil is irradiated with laser light so that the surface roughness is 0.5 at a 10-point average roughness.
To 10 μm of unevenness are formed. Furthermore, the present invention is a metal foil roughened by the above-mentioned roughening method.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As a laser beam used in the roughening treatment of the present invention, a CO2 laser or a YAG laser is used. In the roughening treatment, the metal foil is irradiated with a laser to locally heat the metal foil to evaporate the metal, thereby forming a recess. By continuously irradiating, it is possible to roughen the entire surface of the metal foil or a necessary portion. As the laser irradiation pattern, any of a linear scanning method, a staggered scanning method, a lattice scanning method and a random scanning method can be used, but it is preferable to appropriately select according to a desired roughened shape. . The surface roughness is 10-point average roughness of 0.5 to 10 μm. If it is less than 0.5 μm, the effect on adhesion may not be fully exerted, and
If it is 10 μm or more, the roughness is increased and the effect is not different, which is not economical. In addition, as a matter of course, when the thickness of the copper foil is less than 10 μm, the surface roughness cannot be 10 μm or more and is 1/3 or less of the maximum thickness.

The metal foil used in the present invention includes electrolytic copper foil, rolled copper foil, rolled copper alloy foil, zinc foil, nickel foil,
Although it is represented by a nickel alloy foil such as 42 alloy, it is not particularly limited. The thickness of the metal foil is not particularly limited as long as it has a thickness used as a metal foil that needs to be joined to a resin such as a printed circuit, a heat spreader, and a lead frame.

In order to remove undesired particulate matters such as free splashes scattered on the surface after laser light irradiation,
The surface can be cleaned with adhesive tape or the like. In addition, light buffing can be performed if necessary. Further, a method such as vacuum adsorption or washing with water can be used without using an adhesive tape. Furthermore, you may perform an etching process. By performing the etching process, the roughened shape formed by the laser beam can be made more preferable. That is, it is possible to remove undesired granular metal particles and sharp edges due to the scattering of molten copper. These granular metal particles and steep edge portions, for example, cause etching failure as an obstacle to circuit formation or cause dielectric breakdown. Various etching solutions are used for etching, and for example, ferric chloride aqueous solution, cupric chloride aqueous solution, and sulfuric acid or hydrochloric acid containing an oxidizing agent such as hydrogen peroxide can be used.

In carrying out the manufacturing method of the present invention, for example, a metal foil wound into a coil having a predetermined thickness and width is run at a constant speed in a laser processing apparatus,
It is preferable to continuously wind and manufacture. If necessary, a degreasing treatment, an acid washing treatment, another surface roughening treatment, an anticorrosion treatment, a coupling agent treatment tank and a drying device can be provided at this time. At this time, in the case of a metal foil which is difficult to be coiled, a panel-shaped metal foil having a predetermined thickness, width and length can be subjected to the above treatment by using a transport facility such as a conveyor. For the degreasing treatment, pickling treatment, rustproofing treatment and coupling agent treatment, known methods are appropriately selected and used. The degreasing treatment can be carried out by electrolytic treatment in a degreasing liquid containing various surfactants. The pickling treatment can be performed using an aqueous solution of hydrochloric acid or sulfuric acid. The anticorrosion treatment can be carried out by immersing in a treatment bath containing dichromic acid and, if necessary, performing electrolytic treatment. Further, various metals such as zinc may be contained. The coupling agent treatment can be carried out by spraying or coating an aqueous solution containing various silane coupling agents.

[0010]

EXAMPLES The present invention will now be described in detail based on examples, but the present invention is not limited thereto. (Example 1) Electrolytic copper foil (thickness 15 μm, 1
YAG is applied to the shiny side of the copper foil using 0 point average roughness 0.3).
Fine irregularities were formed on the surface using a laser. After the laser treatment, the surface of the copper foil was washed with 1N hydrochloric acid, the copper foil was thoroughly washed with water, and then a 3.5 g / l aqueous solution of sodium dichromate was immersed in a solution adjusted to pH 5.7 and a temperature of 26 ° C., A chromate-treated layer was formed by performing cathodic electrolysis at a current density of 0.5 A / dm2 and an electrolysis time of 5 seconds. After sufficiently washing this copper foil with water, the copper foil was kept in a dryer kept at 100 ° C for 5
After being dried for a minute, the copper foil of the present invention was manufactured. The surface roughness of the obtained copper foil was measured according to JIS B 0601, JIS B 0
When measured based on 651, the 10-point average roughness was 3.0 μm.

Next, in order to perform the following characteristic test, the above copper foil was laminated on an FR-4 grade glass cloth base material epoxy resin prepreg with the rough surface in contact with the base material surface, and the temperature was adjusted to 168.
Heat and pressure treatment under conditions of ℃, pressure 80kg / cm2, time 60 minutes, length 250mm, width 250mm, thickness 1.6
A copper clad laminate having a size of mm was prepared and used as a test piece. The peeling strength was measured under the conditions based on JIS C 6481. However, the peeling width was 1 mm. Also, for powder removal, the copper foil is entirely removed with a cupric chloride etching solution,
The number of copper particles in 2 mmφ was measured using a magnifying glass with a magnification of 100 to determine the number of powder drops. Table 1 shows the results of the characteristic tests.
It was shown to.

(Example 2) Evaluation was performed in the same manner as in Example 1 except that the surface roughness was set to 5.0 μm. The results are shown in Table 1.

(Example 3) Evaluation was performed in the same manner as in Example 1 except that the surface roughness was set to 0.5 μm. The results are shown in Table 1.

(Example 4) A roughening treatment was performed in the same manner as in Example 1, and a 0.1% by weight aqueous solution of 3-glycidoxypropyltrimethoxysilane was sprayed onto a copper foil having a chromate treatment layer formed thereon at room temperature. Immediately after application, temperature 100 ° C
It was dried for 5 minutes in the drier kept at. Using the obtained copper foil as a test piece, a characteristic test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

(Comparative Example 1) A copper-clad laminate was prepared by using a copper foil which was not roughened by laser light, and its characteristics were evaluated. The results are shown in Table 1.

Comparative Example 2 The characteristics were evaluated in the same manner as in Comparative Example 1 except that the silane coupling agent treatment was performed. The results are shown in Table 1.

[0017]

[Table 1]

As is clear from Table 1, the copper foil subjected to the roughening treatment of the present invention has excellent adhesion to the substrate and is extremely useful.

[0019]

As described above, the metal foil is irradiated with laser light so that the surface roughness is 10 points and the average roughness is 0.5 to 10 μm.
The metal foil formed with the unevenness of m has excellent adhesiveness with the resin,
There is no powder drop and it is extremely useful in practice.

Further, in the present invention, since a roughening treatment liquid such as an aqueous solution of copper sulfate, a chemical conversion treatment liquid and an etching treatment liquid, which have been conventionally required in the roughening treatment, are not used, wastewater treatment is not necessary and management is extremely easy. In addition, it has the advantage that it has little impact on the environment, has excellent mass productivity on an industrial scale, and its value is great.

Claims (5)

[Claims] 1. A method for roughening a metal foil, which comprises irradiating a metal foil with a laser beam to form irregularities having a surface roughness of 10 to 10 μm in average roughness. 2. A metal foil roughened by the roughening method according to claim 1. 3. The metal foil according to claim 2, which has a rust preventive layer on its surface. 4. The metal foil according to claim 2, which has a coupling agent treatment layer on its surface. 5. The metal foil according to claim 3, wherein the metal foil is a copper foil.