JPS62158859A - Pretreatment - Google Patents

Abstract

PURPOSE:To improve adhesive strength of dry plating, by subjecting a metallic substrate to ion bombardment by use of inert gas and then to ion bombardment by use of hydrogen gas. CONSTITUTION:Prior to the application of dry plating to the metallic substrate of copper (alloy), etc., ion bombardment is first applied by use of inert gas such as argon gas, etc., so as to remove adsorbates on the oxides at the substrate surface, such as oil, dust, etc., followed by ion bombardment by use of hydrogen gas, so that adsorbate-free oxides at the substrate surface are removed by reduction and the metallic-substrate surface is provided with high cleanliness. According to the above method, adhesive strength between the dry-plated film and substrate can be improved by means of short-time treatment without causing distortion in the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a pretreatment method for cleaning the surface of a metal substrate before performing dry plating on the substrate. The pretreatment method of the present invention is very advantageous when applied to lead frames for rC and the like.

[Conventional technology]

In general, the required characteristics for dry plating include film quality, substrate
There are a wide range of factors in terms of quality, such as adhesion between films and deposition rate, as well as economic aspects.In terms of quality, adhesion between substrates and economic terms, takt time is important.

Conventionally, when dry plating is performed using physical vapor deposition (PVN) or chemical vapor deposition (OVD), the substrate is heated in a vacuum chamber or heated in an inert gas to ensure adhesion between the substrate and the coating. The substrate was cleaned using ion bombardment or the like. However, although these methods cause the destruction of surface adsorbed substances due to gas release due to substrate heating and argon ions, etc., these methods are sufficient to destroy substances with strong adhesion such as oxides formed on the surface of metal substrates. This phenomenon is especially noticeable when the substrate material is copper or copper alloy, and even if the adhesion between the substrate and the workpiece is deteriorated, this phenomenon is particularly noticeable when the substrate material is copper or copper alloy. It was very difficult to obtain such a coating.

As countermeasures to this problem, so-called pretreatment enhancements are being taken, such as extremely raising the substrate temperature, lengthening the ion bombardment time in an inert gas, or subjecting the substrate to pickling before placing it in a vacuum container. is the current situation.

[Problem that the invention seeks to solve]

By the way, although the above-mentioned method improves the adhesion to some extent, the increase in substrate temperature causes problems such as surface oxidation due to residual oxygen and heavy equipment load depending on the degree of vacuum due to thermal strain on the substrate.

In addition, introducing pickling of the substrate will not only complicate the process but also be extremely disadvantageous in terms of cost. In addition, increasing the ion bombardment time in inert gas
As the takt time is longer, the cost is higher, and the substrate is exposed to plasma for a longer period of time, the substrate temperature rises and the so-called reverse sputtering phenomenon occurs in which dirt from the deposition chamber wall re-adheres to the substrate. It's hard to say. As mentioned above, conventional methods have various problems in terms of quality and economy.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a pretreatment method for annealing the surface of a metal substrate that eliminates the above-mentioned drawbacks, and is particularly effective for copper or steel alloy substrates. That is, the purpose of the present invention is to process the cleaning of the substrate surface simply and in a short time when performing dry plating, and to significantly and reliably improve the adhesion between the substrate and the wt film even on copper or copper alloy substrates. To provide a processing method. Note that the dry plating referred to here refers to physical vapor deposition such as vacuum deposition, ion blating, and sputtering, and chemical vapor deposition including those using plasma RF.

[Means for solving problems]

In the present invention, in a pretreatment method for completely cleaning the surface of a metal substrate before applying a coating using a dry plating method, ion bombardment is first performed using an inert gas, and then hydrogen gas is used To perform an ion bombardment
- A pretreatment method characterized by this, which achieves the above objectives. Particularly preferred embodiments of the present invention include the above method in which the metal substrate is a copper or copper alloy substrate, or the above method in which the dry plating method is a physical vapor deposition method or a chemical vapor deposition method.

That is, the present invention provides a pretreatment method for cleaning the surface of a metal substrate made of steel or steel alloy prior to dry peeling in a vacuum container, in which the surface is first subjected to ion bombardment using an inert gas such as argon gas, etc. This process removes adsorbed substances such as oil and dust on the oxide on the surface of the metal substrate.
Remove with heavy ions such as argon.

Thereafter, by ion bombardment of hydrogen gas), oxides free of adsorbed substances on the surface of the metal substrate are reduced and removed, thereby making the surface of the metal substrate extremely highly clean.

In this case, ion bombardment using hydrogen gas alone will
Since the atomic mass of hydrogen itself is extremely low, it is impossible to remove oil, dust, etc. from the substrate, and it is impossible to completely reduce the underlying oxide. In other words, the surface of the metal substrate cannot be sufficiently cleaned, and the adhesion between the substrate and the film cannot be stabilized or improved.

Therefore, according to the present invention, the metal substrate surface can be sufficiently cleaned, which could not be achieved by conventional methods such as single ion bombardment or substrate heating. Furthermore, as described above, in the present invention, ion bombardment is performed in two stages, but there is clearly a priority between first performing ion bombardment using inert gas and then using hydrogen gas. is required. For example, if hydrogen gas ion bombardment is performed before inert gas ion bombardment, the oxide in the portions of the silicon oxide that do not have strong adsorbents is reduced and removed by hydrogen gas ion bombardment, and the subsequent Ion bombardment with an inert gas will partially remove the stubborn adsorbates on the remaining oxide. This thing is
By partially leaving oxides on the surface of the metal substrate, the clean surface from which oxides have been removed (by hydrogen gas ion bombardment) is bombarded again with argon ions, creating a reverse spunter effect. new adsorbed substances are generated, and as a result, a highly clean substrate surface cannot be obtained, and the substrate
The only thing that can be done is to improve the adhesion between the coatings.

As explained above, in the present invention, it is possible to completely remove adsorbed substances and oxides from the surface of a metal substrate made of steel or copper alloy, and it is also possible to completely remove adsorbed substances and oxides from the surface of a metal substrate made of steel or copper alloy. A highly clean substrate surface can be obtained without contamination.

Thereafter, the adhesion between the substrate and the coating can be significantly improved by subsequently forming a protective coating by physical vapor deposition or chemical vapor deposition.

Although the present invention involves pretreatment by ion bombardment, the points that are different from conventional ion bombardment are as follows: 1) Conventional single ion bombardment is performed (2-stage ion bombardment is performed). 2) The two stages are ion bombardment using inert gas and hydrogen gas. 3) Also, to carry out the two stage ion bombardment,
, priority is defined in terms of process, and ion bombardment of hydrogen gas must be performed after ion bombardment of inert gas.

Ion bombardment using an inert gas in the present invention uses, for example, argon gas and
It is sufficient to carry out the test under conditions of about 5 minutes. Ion bombardment using hydrogen gas may also be performed under conditions of 10 to 10 Torr, DO% IKV, and about 5 minutes.

The effects of the present invention will be explained below using Examples.

〔Example〕

Using a substrate made of phosphor bronze with a thickness of 0.25 m, a length of 2001 m, and a width of 1501) m, the substrate was pretreated under the conditions shown in the notes in Table 1, and then argon gas was introduced at a substrate temperature of 50 C. At the same time, the shim was subjected to DC ion blating at a vacuum level of 3 x 10 Torr, and the thickness was 4 μm.
1 of analytes III were obtained.

When the substrate was subjected to a 180 degree bending test for adhesion, the results shown in Table 1 were obtained.

The evaluation column in Table 1 is based on the following criteria.

When the board after the bending test is placed on two distorted planes so that the center part contacts the plane, and the distance between the plane and the edge of the board (the amount of warpage of the board) is h, h ○ for <0.5wx, Δ for 0.3≦h≦0.5 ynt, h > 0
．． 5 yn was designated as X.

A beading test was carried out by applying adhesive tape to the film and peeling it off. The adhesive strength of the adhesive tape used is 1
0kP/1M2, when this test was conducted with 50 samples, those with 0 peeling number were ○, those with ~10 were Δ, and those with ~1) were ×.・Overall evaluation 2 The above distortion and The overall evaluation was based on whichever of the adhesion evaluations was worse. For example, the following strain Adhesion Comprehensive evaluation XOX Δ × Otherwise, the board may be distorted.

2) Pretreatment using only argon ion bombardment does not provide stable adhesion even after long-term treatment, and also causes distortion in the substrate.

3) Stable adhesion ρ cannot be obtained with pretreatment using only hydrogen ion bombardment.

4) According to the present invention, good adhesion can be obtained in a short time without causing distortion to the substrate.

I was able to find out the facts.

Incidentally, in carrying out the present invention, it is of course possible to use substrate heating, electron beam irradiation to the substrate, etc. in combination.

Table 1 Note) Argon bombardment: 5 X 10-3 Torr
DCIKV Hydrogen Bombardment: Same as above [Effects of the Invention] As detailed above, the present invention performs ion bombardment of an inert gas on the surface of a metal substrate, particularly a substrate made of copper or a copper alloy, and then performs hydrogen bombardment. The simple operation of ion bombarding the substrate makes it possible to perform extremely clean cleaning in a short period of time without causing distortion to the substrate, significantly improving the adhesion between the substrate and the coating. You can force it.

Claims (3)

[Claims] (1) In a pretreatment method for cleaning the surface of a metal substrate before applying a coating using a dry plating method,
A pretreatment method characterized by first performing ion bombardment using an inert gas, and then performing ion bombardment using hydrogen gas. (2) The pretreatment method according to claim (1), wherein the metal substrate is copper or a copper alloy. (3) The pretreatment method according to claim (1), wherein the dry plating method is a physical vapor deposition method or a chemical vapor deposition method.