EP0816535B1 - After-treatment of an electroformed magnetic metal piece - Google Patents

Description

The invention is based on a method for Reworking an electroplated magnetic Sheet metal, which structures, in particular lowered microstructures.

State of the art

Starting point for the production of highly planar mold inserts a so-called. Master structure. It can be done in league technique, in photoresist technique, Silicon microstructure technology or otherwise be made. By electroplating one such a microstructured master structure is produced the mold insert for the impression tool. To stress-free To get mold inserts, the galvanic impression must be very stress-free with a large thickness, approx. 3 - 5 mm, be performed.

The sheets obtained by electroplating are ground and fitted into the impression tool. Disadvantageous is that the deposition rate in electroplating must be set up very slowly to the necessary Achieve tension-free. The total duration of one Electroplating can take up to four weeks. In expensive systems are blocked during this time. Another The disadvantage is that a master structure in the Usually only a single mold insert can be produced. However, this has cost reasons (duration of the electroplating impression) also quality reasons, since the deviations from the planarity in further generations of impressions e.g. B. in the third generation sheet are higher than in the first generation sheet. Can from one Master structure made only a single mold insert the costs per mold insert increase here too (Master structure production is usually expensive).

Advantages of the invention

With the measures according to claim 1, it is possible especially thin, approx. 1 mm, not plane galvanic to obtain molded nickel sheets absolutely plane-parallel, without affecting the structures. The invention It is particularly suitable for thin thin parts Nickel sheets made by mechanical finishing be aligned plane-parallel.

With the measures of the invention, several Mold inserts inexpensive thanks to multiple copying technology produce. A time consuming voltage free galvanic Impression with rigid and thick sheets, one Do not allow multiple copying technology, is unnecessary. At "thicker" electroplating, i.e. H. Sheet thicknesses of more than 3 mm, there is no post-planarization during regrinding because the sheet is almost completely rigid due to its thickness. With this technique, the planarity of the Use of shape due to the absence of tension in the electroplating certainly.

Claims 1 to 5 relate to further developments of the inventive method.

drawings

Figur 1 die übliche Herstellung eines Nickelbleches durch galvanische Abformung,

Figur 2 die Herstellung eines Nickelbleches durch galvanische Abformung durch eine Mehrfachkopiertechnik,

Figur 3 das unbearbeitete nicht spannungsfreie Nickelblech vor der magnetischen Aufspannung,

Figur 4 das magnetisch aufgespannte Nickelblech,

Figur 5 das nachbearbeitete Nickelblech vor der Montage in einem Abformwerkzeug und

Figur 6 den Schutz der Mikrostruktur durch Lack.

The invention will now be explained in more detail with reference to the drawings. Show it

FIG. 1 shows the usual production of a nickel sheet by means of electroplating,

FIG. 2 shows the production of a nickel sheet by means of galvanic molding using a multiple copying technique,

FIG. 3 shows the unprocessed, non-stress-free nickel sheet before the magnetic clamping,

FIG. 4 shows the magnetically clamped nickel sheet,

5 shows the reworked nickel sheet before assembly in an impression tool and

6 the protection of the microstructure by means of lacquer.

Description of the invention

In Figure 1, the conventional manufacture of a Microstructured galvanically molded Nickel sheets (nickel shim) from a master structure in "thick" electroplating shown. Such a nickel sheet is 3 - 6 mm thick, not flexible and due to an extreme voltage-free galvanic process manufactured with a Total duration of the electroplating impression of several weeks.

The shim planarity in the structure zone (middle area between the V-grooves for the optical fiber couplings) is ≥ 20 µm. Because of the duration of the electroplating impression and also for quality reasons, this technique is not suitable for Production of multiple copies.

In the molding process shown in FIG. 2, thin, approx. 1 mm thick, flexible and not tension-free Nickel sheets molded from a master structure. It will be a fast nickel electroplating process used with a process time of 1.5 - 14 hours per shim. Of these Shims can make multiple copies - Figure 2 shows a total of 16 such copies - are made if they are then with the inventive method, as in the Figures 3 to 5 shown, have been reworked.

As FIG. 3 shows, this is galvanically from the master structure molded and with lowered microstructures 4 provided nickel sheet 1 domed, d. H. not stress-free, and also not of uniform thickness. That in Figure 3 still arched nickel sheet is under magnetic force (magnetic forces) against an absolute plan magnetic clamping block (plane mounting table 2) excited, the magnet 2 the nickel sheet in all Must be able to drag areas to its surface. The Clamping takes place so that the structure side of the Nickel sheet points to the magnet surface of the magnet. The prerequisite for this is that the sheet is not too thick (less than 1.5 mm). Before clamping, the Nickel sheets 1 with the lowered microstructure areas pretreated for the grinding process by a drop of a later removable paint 3, z. B. polymethyl acrylate solved in z. B. ethyl acetate, so in the Lowering 4 is dripped that the bottom of the lowering and the microstructures are completely covered (Fig. 6).

It should be noted that there is no paint on the shim surface reached. After drying is the microstructure against damage during the grinding process, e.g. B. metallic grinding dust or liquid abrasive, protected. Clamping the metal sheet 1 on the Magnet 2 is made so that the microstructures 4 to Magnet 2 point out. The back of the sheet metal is then mechanically processed so that the metal sheet 1 a plane-parallel shape. This can be done geometrically indefinite cutting edge (grinding) or geometric certain cutting edge (milling, etc.) especially with a Surface grinding, milling or planing machine.

In Figure 4 is the machining direction of grinding (Grinding). After removing the magnetic Clamping block turns the post-processed planarized Nickel sheet due to its tension again and picks up the curved shape according to Figure 5. The protective lacquer 3 can e.g. B. at 60 ° C with chloroform.

After clamping the finished nickel sheet on a plan plate in a casting tool for plastic impression the front of the sheet is very flat. Were measured about 8 µm bumps on 40 mm.

The reworked nickel sheet is suitable as a mold insert in a casting tool for plastic impressions and in particular for injection molding, hot stamping or reaction casting processes. It can be used particularly advantageously for producing integrated optical waveguide components, for example according to DE-A-44 01 219 or DE-A-196 19 353 , and for all other planar microstructures. Instead of a magnetic clamping block with a permanent magnet, an electromagnetic clamping block can also be used.

Claims (5)

1. A method of reworking a galvanically formed magnetic metal sheet (1) provided with structures, in particular recessed structures, comprising the following steps:

   the metal sheet (1) is magnetically clamped on a magnet (2) having a plane surface in such a way that the structured side faces the magnetic surface of the magnet (2), and

   the back side of the metal sheet is mechanically machined by such ways and means that the metal sheet (1) assumes a plane-parallel shape.
2. The method according to claim 1, characterized in that the recessed microstructures (4) are protected by a removable lacquer (3) prior to reworking.
3. The method according to claim 1 or 2, characterized in that the magnetic clamping step is performed using a magnetic plane mounting table.
4. The method according to any of the claims 1 to 3, characterized in that the magnetic clamping step is performed using an electromagnetic plane mounting table.
5. The method according to any of the claims 1 to 4, characterized in that the surface grinding of the back side of the metal sheet is done with a surface grinding machine, a planing machine or a milling machine.

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