JPH07242983A - Mold member improved in wear resistance - Google Patents

Abstract

PURPOSE:To produce a mold member having high wear resistance and resin adhesion resistance and improved in reliability and service life by coating the surface layer part of a base material composed of sintered hard alloy or cermet, having low hardness and superior toughness, with CBN to sufficient thickness. CONSTITUTION:The surface layer part of a base material composed of WC-base sintered hard alloy or TiC- or TiNC-base cermet, having <=92.0 hardness HRA, is coated with CBN to sufficient thickness by a high-frequency plasma CVD method, etc. By constituting the whole or a part of a mold member by using the resultant CBN-coated member, the mold member causing no breakage even in a thin-walled state and having high reliability and long service life can be obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a CBN coated member having improved reliability and service life.

[0002]

2. Description of the Related Art In the process of mounting an IC on a lead frame, various kinds of carbide punches and dies have been conventionally used. In particular, a punch for punching a lead frame, a die, a tie bar cut punch, and a die are generally made of cemented carbide. However, in recent years, the patterning of the lead frame has become finer and the material of the lead frame has been changed to thin and hard in order to improve the performance of IC chips (increasing the number of pins). Therefore, punches for punching lead frames and die materials that are thin and do not break, and that are hard and have excellent wear resistance have been demanded.

[0003]

However, with conventional cemented carbide, it is extremely difficult to dramatically improve both toughness and hardness, and if the material has toughness that does not break even if it is thin, it becomes hard. Inevitably becomes low and a sufficient service life cannot be obtained.

[0004]

In order to overcome the hardness of recent lead frames, it is ideal that the surface of the member is made of a material harder than cemented carbide, that is, CBN. However, due to the recent tendency to increase the number of pins, there is a tendency for the overall thickness of the members to decrease, starting with the punch. When CBN is used for such a thin member, the fracture strength and the fracture toughness are lower than those of conventional cemented carbides, so that the frequency of breakage increases and it cannot be put to practical use.
As a result of intensive studies on the method of coexisting these contradictory properties in one member, the present inventors solve the problems by forming a hard CBN surface and corrosion resistance, and a tough cemented carbide or cermet structure inside. Came to. Hereinafter, a detailed description will be given according to the claims.

[0005]

The thickness of the coating film is defined by the intended use, and if it is too thin, sufficient abrasion resistance cannot be ensured and unevenness is likely to occur, which is contrary to the gist of the present invention. On the other hand, if it is too thick, the wear resistance can be secured, but the fracture toughness value is lowered, and it tends to be broken, which also goes against the gist of the present invention. The substrate is WC-based cemented carbide having a hardness of HRA92.0 or less or cermet. By setting the HRA to 92.0 or less, toughness can be secured,
Even if it is used as a thin-walled member, the frequency of breakage is low and it can be sufficiently put to practical use. Specifically, punches and dies for punching lead frames, tie bar cut punches, dies and the like as members are greatly improved by the application of the present invention due to their use.

[0006]

EXAMPLE First, raw material powders such as WC, Co and Cr were weighed in a predetermined ratio and wet-mixed for 72 hours in a ball mill using alcohol as a dispersant. Next, the mixed powder was dried by spray drying, granulated, press-molded into a predetermined shape, and further sintered by appropriately selecting appropriate sintering conditions. After sintering, the surface coating treatment was performed mainly on the portions that come into contact with the resin after being processed into the respective shapes. If necessary after the coating treatment, further final processing was performed. The coating process is a method generally used at present, that is, high frequency plasma CVD (process 1), microwave CV
D (Treatment 2), laser PVD (Treatment 3), and electron beam PVD (Treatment 4) were appropriately performed to form a diamond thin film and a DLC thin film in a predetermined film thickness depending on the application. The thus produced cemented carbide member, that is, a lead frame punching punch and a tie bar cut punch were produced and compared with those of the conventional product not subjected to the covering treatment, and the breakage frequency and wear resistance were investigated.

[0007]

[Table 1]

[0008]

[Table 2]

[0009]

[Table 3]

[0010]

As described above, various mold members using the cemented carbide material having the surface coated with CBN can obtain the property that the breakage frequency is low and the wear resistance is excellent.

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Claims (2)

[Claims] 1. A WC-based cemented carbide or TiC having a hardness HRA of 92.0 or less, in which the surface layer portion is coated with CBN to a sufficient thickness.
Alternatively, a die member such as a punch or die for punching a lead frame for IC mounting, which is wholly or partly composed of a TiCN-based cermet, has improved wear resistance. 2. The surface layer portion having a sufficient thickness according to claim 1,
A punch or die for punching a tie bar portion with improved wear resistance, characterized in that it is wholly or partly composed of a WC-based cemented carbide having a hardness of HRA 92.0 or less coated with BN or a TiC or TiCN-based cermet. A mold member having improved wear resistance such as (hereinafter abbreviated as tie bar cut punch and die).