JPH01246389A - Production of metal mold - Google Patents

Abstract

PURPOSE:To smoothen the electrodeposited surface of a metal mold by carrying out conventional high-speed electrodeposition and supplying electric current in the backward direction or repeatedly supplying electric current in the backward direction and electric current in the forward direction to dissolve part of the surface of an electroformed layer. CONSTITUTION:When electroforming is carried out on a matrix, conventional high-speed electrodeposition is carried out in a first stage. In a second stage, electric current in the backward direction is supplied or electric current in the backward direction and electric current in the forward direction are repeatedly supplied. By this current supply, the tips of electrodeposited coarse grains having high surface energy are preferentially dissolved and the resulting electrodeposited surface is smoothened. Thus, an electroformed layer having a smooth surface is formed without strictly controlling electroforming conditions or adding a leveling agent and a metal mold for molding a substrate, etc., can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a mold, particularly a substrate molding mold (hereinafter referred to as a standber). This is a mold manufacturing method particularly suitable for performing high-speed electroforming.

[Prior Art] Conventionally, a stamper is manufactured by sputtering or electroforming a metal such as nickel onto a glass master with a patterned resist or the like, transferring the patterning on the resist, and then peeling it off. ing.

Since the electroforming process takes a particularly long time among the standby manufacturing processes, many high-speed electroforming technologies aimed at reducing the electroforming time have been reported.

(Galvanotechnlc (Sau1gau/
Vurtt, ) 5B (1965) Nr, B) However, high-speed electroforming causes coarsening of electroformed crystal grains, resulting in a rough electroformed surface.

When high-speed electroforming is performed in a nickel sulfamate-based electroforming bath, which is the usual method of manufacturing a standby, the crystal grain size on the electroformed surface grows to several tens of μm to several hundred μm, and the roughness of the electroformed surface is Rwax. It can be several tens of micrometers.

Generally, the electroformed surface of a stamper is precision polished to achieve a mirror finish due to transferability issues to plastic substrates, but in order to make this electroformed surface a mirror finish, polishing is required for a long period of time. Or, it is necessary to increase the load. As described above, if a large load is applied to the polishing process, beer will be generated due to the loss of coarse crystal grains, which will cause defects in the plastic substrate transferred from the mold. Furthermore, several μm ~
Polishing by several tens of μm causes unevenness in the thickness of the mold, which causes unevenness in the thickness of the plastic substrate, which causes deterioration of the mechanical properties of the substrate. Therefore, when performing high-speed electroforming, the pH is ±0.1. Current density is ±0, lA/dn+2.
Although the temperature is very strictly controlled at ±1° C., even with these controls, the roughness of the electroformed layer cannot be completely controlled.

Therefore, a method of improving the roughness by mixing a smoothing agent into the electroforming bath is sometimes applied. However, addition of a surfactant not only causes deterioration of the electroforming bath, but also introduces large stress into the electroformed layer, causing warping of the taper.

If the stand bar is warped, it will not be able to be set in an injection molding machine during plastic molding, making it practically unusable. Therefore, the crystal grains on the electroformed surface are usually controlled by controlling the electrolyte composition, use of additives, temperature, pH, current density, etc., but this requires very strict control and has problems such as poor reproducibility. The current situation is that it is unavoidable.

[Problems to be Solved by the Invention] The problems to be solved by the present invention are as described above. The electroformed surface becomes very rough and puts a strain on the polishing process, so polishing requires a long time.
The problem is that electroformed crystal particles are missing, resulting in the generation of beer, and variations in thickness distribution.

[Means for Solving the Problems] In order to solve these problems, the present invention, in the process of performing electroforming on the mother mold, has a first process of performing normal high-speed electroforming and a process in the opposite direction. The electroformed surface is roughened by the second step of dissolving a part of the surface of the electroformed layer formed by passing a current or repeatedly passing a current in the opposite direction and a current in the forward direction and repeating melting and precipitation. The present invention provides a method for manufacturing a mold having a smooth electroformed surface by melting crystal grains.

[Function] According to the present invention, after performing normal high-speed electroforming, a reverse current or a reverse current and a positive current are repeatedly passed to reduce the surface energy of coarse crystal grains formed by electroforming. By melting preferentially from the high end portion and smoothing the electroforming surface, the above problems can be solved without requiring strict control of electroforming conditions and without adding a smoothing agent. The first step of electroforming of the present invention may follow a conventional method. The electroformed layer may be made somewhat thicker in consideration of dissolving part of the surface later.

There is no particular restriction on the current density in the opposite direction for melting the surface of the electroformed layer having coarse crystal grains formed by electroforming, but
It is preferable that the current density is somewhat lower than that in the case of normal electroforming, and - within the film, a current density of about several to several tens of A/dm2 is good. This reverse energization may be performed by passing current in a pulsed manner, and the waveform of the pulse is not particularly limited, and a sine wave, rectangular wave, triangular wave, side wave, etc. may be used. The height, width, interval, etc. of the pulses may be determined as appropriate depending on the melting of the electroformed layer. Furthermore, in addition to reverse energization, electroforming by energization in the forward direction may be performed midway through.

Therefore, pulses may be used in both forward and reverse directions, and melting methods may also be applied in which melting and precipitation are repeated using pulsed current, and as a result, the initially formed electroformed layer is slightly melted. At this time, the waveform of the pulse in both the forward and reverse directions may be a sine wave, a rectangular wave, a triangular wave, a side wave, or the like. In addition, the wave height, width, interval, etc. are determined in a timely manner as in the case of reverse energization.

By using the above method, the surface of the electroformed layer is smoothed, and the electroformed surface produced by high-speed electroforming, which does not require strict control, is usually finished to a thickness of 2 μm or less using RIIax, which solves problems in the polishing process. Can be done.

[Example] Next, the present invention will be explained in more detail with reference to Examples.
- Examples are given, and the present invention is not equally limited to these examples.

(Example 1) Using the electrolytic bath shown in Table 1, constant current high-speed electroforming was performed for 2 hours under the conditions shown in Table 2 as the first step.

After completion, the second step is to immediately reverse the energization and turn the I
As a result of constant current melting for 10 minutes at a current density of OA/dr#, the roughness of the electroformed surface was 1°5 μm in Rl1ax. On the other hand, the roughness of the electroformed surface when reverse energization was not performed was 54 μm in RlaX.

Table 1 Table 2 (Example 2) Constant current high-speed electroforming was performed for 2 hours in the same manner as in Example 1.

Then, as a second step, the current is quickly reversed and I
OA/drr? The electroformed cathode was removed after repeating the melting and precipitation operation 10 times, in which the electrode was melted at a constant current for 5 minutes at a current density of Ta. The roughness of the electroformed surface is R
1 laX is 0. It was 9 μm. On the other hand, when the second step was not carried out, the roughness of the electroformed surface was 60 in R1laX.
It was μm.

[Effects of the Invention] As explained above, according to the mold manufacturing method of the present invention,
It is possible to smooth the surface of the electroformed layer without requiring strict control of electroforming conditions and without adding a smoothing agent, and it is possible to solve problems that occur during the polishing process and warpage.

Claims (1)

[Claims] In the process of manufacturing a mold by electroforming on the mother mold, a current is passed in the opposite direction to the first process of electroforming, or a current in the opposite direction and a current in the forward direction are repeatedly passed to melt and melt. A method for manufacturing a mold, comprising a second step of dissolving a part of the surface of the electroformed layer formed by repeated precipitation.