WO2023213538A1

WO2023213538A1 - Method and equipment for corrective machining of microtechnology workpieces

Info

Publication number: WO2023213538A1
Application number: PCT/EP2023/060076
Authority: WO
Inventors: Grégoire Genolet; Alain HESS; Ivan Calderon; Philippe Jacot
Original assignee: Mimotec Sa
Priority date: 2022-05-03
Filing date: 2023-04-19
Publication date: 2023-11-09

Abstract

The present invention relates to equipment for the corrective machining of metal workpieces (10, 10') previously produced by a LIGA (lithography, electroplating and moulding) method and comprising a machining apparatus (200) comprising means for the forceless machining of said metal workpieces (10, 10') and a control system for controlling said forceless machining means. The equipment comprises a system for recording at least one predetermined target geometry and at least one predetermined reference position (x1, y1, z1) which are specific to each metal workpiece positioned on a support (2) with respect to a reference frame of reference. The corrective-machining equipment makes it possible to determine and perform a geometry correction that needs to be made in relation to the target geometry. The invention also relates to a method for the corrective machining of metal microtechnology workpieces (10, 10') previously produced by a LIGA (lithography, electroplating and moulding) method, said method comprising the various steps (A-F) consisting in: A) providing, on a support (2), metal workpieces (10, 10') previously produced by a LIGA (lithography, electroplating and moulding) method; B) providing said corrective machining equipment and inserting at least one of said supports (2) in said machine apparatus (200); C) recording, in a fabrication frame of reference (X1Y1Z1) used during the production of the metal workpieces (10, 10') via the LIGA method, a predetermined target geometry and at least one predetermined reference position (x1, y1, z1) specific to each metal workpiece (10, 10') positioned on the support (2) with respect to a reference frame of reference; D) recognizing, within at least a corrective-machining frame of reference (X-Y-Z) connected with said fabrication frame of reference (X1Y1Z1), the 3-D geometry and positioning of the metal workpieces (10, 10') previously produced by a LIGA method , and determining a geometry correction to be applied with respect to said target geometry and to said reference position (x1, y1, z1) recorded using said viewing system (140) and said computation unit (120); E) performing corrective-machining steps on said metal workpieces (10, 10') using said forceless machining means (100) which, prior to the corrective machining of each metal workpiece (10, 10') are moved and positioned in the reference frame of reference with respect to said metal workpiece (10, 10') that is to be corrected so as to perform the corrective machining according to the geometry correction determined in step D so as to obtain the target geometry; and F) releasing at least one of said metal workpieces (10, 10') from its support (2).

Description

METHOD AND EQUIPMENT FOR CORRECTIVE MACHINING OF MICROTECHNICAL PARTS

Field of the invention

The invention relates to the general field of microtechnology and in particular the corrective machining of parts by force-free machining means. The invention relates more particularly to a method and equipment for corrective machining of small metal parts, previously produced by a LIGA process, using force-free machining means, such as a very short pulse laser.

Machining equipment finds particular application in the watchmaking industry, particularly for the production of watch parts. We can also cite applications in the fields of fluidics (nozzles) and medical (bearings, insulators) and connectors (test tips).

State of the art

The use of small parts made of metals is known in various fields such as medical applications or watchmaking.

Traditional machining techniques are mainly limited to machining or shaping techniques using abrasives or chemical techniques or plasma treatment.

Another technique consists of producing microtechnical parts using a LIGA process (Lithography Galvanoformung Abformung). Initially the technique was intended to operate with X-rays. The need to implement expensive equipment (synchrotron) makes this technique hardly compatible with mass production of microstructures which must have a low unit cost. This is why, on the basis of this LIGA process, similar processes have been developed but using resins photosensitive to ultraviolet (UV) radiation. Such a process is for example described in the publication by A. B. Frazier et al., entitled “Metallic Microstructures Fabricated Using Photosensitive Polyimide Electroplating Molds”, Journal of Microelectromechanical Systems, Vol. 2, Issue 2, 87-94, June 1993. This article describes a process for the manufacture of metallic structures by electrodeposition of metal in photosensitive resin molds based on polyimide.

LIGA technology makes it possible to produce geometries that are unrealizable using standard production processes. LIGA technology is an additive technique that has the advantage of being very inexpensive and can be implemented quickly, which makes this process very competitive with traditional methods by material removal. The process is ideal for rapid prototyping as well as for large series production and makes it possible to achieve a good level of micrometric precision as well as good surface finish quality.

The UV-LIGA process requires tooling, industrial equipment and techniques that are very different from conventional micro-manufacturing methods.

A typical process of the LIGA technique consists of:

- deposit on a substrate a layer of 1 to 1000 μm of a photosensitive resin called photoresist;

- carry out, if necessary, a planarization of the photoresist layer by mechanical machining;

- carry out irradiation through a mask using a synchrotron or by exposure to ultraviolet rays;

- develop, that is to say eliminate by chemical means, the unpolymerized photoresist portions and thereby create a photoresist cavity or mold;

- carry out selective gold plating on the upper surfaces of the photoresist cavity in the case of producing a cavity on several levels;

- repeat the previous steps to create cavities on several levels;

- electroform a metal in this cavity in order to obtain the micromechanical component.

It is also possible to produce microparts that include more than a single element. For example, document EP 1 916567 describes a mixed manufacturing process for parts by photolithography, addition of inserts and electroforming. This process requires the assembly of at least two elements, one obtained by photolithography and galvanic growth, and the other by another manufacturing process, and it includes the following steps:

- irradiation through a mask of a layer of photosensitive resin applied to a substrate;

- development of the photosensitive resin layer to form a polymerized resin mold;

- placement of an added element obtained by another manufacturing process in the polymerized resin mold; - deposition of a metal layer by electroforming on the substrate so that the growth of the metal layer surrounds all or part of the added element;

- obtaining the part by separation of the substrate from the electroformed metal layer attached to the added element and elimination of the photoresist mold.

The microstructures obtained according to the methods of the prior art have limited precision, which results from the nature of the LIGA process.

The microstructures obtained according to the processes of the prior art are metallic microstructures made from a single metal, which is not always optimal, particularly for watchmaking applications. Indeed, it may be interesting, for aesthetic, tribological or more generally mechanical reasons, etc., to produce bimetal microstructures comprising at least one part made of a first metal inserted in a part made of a second metal.

Usually, to produce such bimetal microstructures, the insert (or inserts) in a first metal is (or are) attached in a traditional manner to the part in a second metal by embedding, crimping, screwing or other stamping.

The process based on photolithography and electroforming makes it possible to obtain shapes and precisions unmatched by traditional methods. Despite this very good precision, the demand for even better performance continues to increase.

With the LIGA process, the control of dimensions (diameter and verticality, for example for a hole), depends on many parameters. We can cite for example, the geometry of the resin (which itself depends on the parameters of the lithographic process), then the evolution of this geometry during electrodeposition. The size of the cavities, the type of photoresist, the height of the photoresist, the type and thickness of the metal deposited, for example, are important parameters.

Repeatability is extremely complicated to master due to all of these factors.

It is therefore obvious that to precisely and repeatably obtain a hole, for example, in a microstructure manufactured by LIGA, rigorous control of the parameters mentioned above must be carried out. This is technically and economically unimaginable for all parameters. Each hole diameter and each thickness will require specific adjustments to these parameters. If a microstructure has several holes with diameters and/or thicknesses different, it is easy to understand that the precision obtained is the result of a series of compromises.

In the field of microstructures manufactured by UV photolithography and electroforming, there is no solution which makes it possible to obtain precisions lower than +/-2 pm, or even +/- 1 pm in the best case, in a reproducible manner in the time. This resolution limit is mainly linked to the difficulty in obtaining the target value at the center of the tolerance interval. The resolution limit and geometric conformity, in particular the verticality of the sides, is the result of optimization and compromise, but is limited by the materials and installations used and is strongly linked to the indirect nature of the process. Indeed, a hole in a part, for example, is defined by a resin mold, followed by an electroforming step. The final result therefore depends on a multitude of parameters and manufacturing steps.

There is therefore the need to have a new technique which makes it possible to improve the precision of micro-mechanical components produced by the LIGA technique and without substantially increasing the cost of their production.

Object of the invention

The invention relates to a method and equipment for corrective machining, in particular by laser, of a large number of small parts previously produced by a LIGA process. The direct production of precise and repeatable dimensions has reached its limits with the UV-LIGA process. To ensure even higher accuracies and tolerances, targeted re-machining by force-free machining means, for example by a pulsed laser, is offered. The retouching of critical dimensions is done on identified and sketched elements.

More precisely, the equipment and the method of the invention make it possible to correct extremely quickly and reliably by force-free machining of parts previously produced by a LIGA process, said parts having been produced on a substrate and then transferred to another support. . The method and equipment of the invention make it possible to produce a plurality of parts of very precise dimensions, brought and arranged on a support, at high speed and without substantially increasing their manufacturing cost.

The equipment and method of the invention make it possible to use force-free machining machines, preferably by laser, for example by a femtosecond laser, which are extremely expensive machines, at their maximum capacity. This is key in the field of manufacturing timepieces but also precision medical parts such as used for example in endoscopes. A particular application aims to produce curved surfaces and holes and openings in LIGA parts with very high precision.

In a first aspect the invention is obtained by corrective machining equipment for microtechnical metal parts previously produced by a LIGA process, comprising a machining machine comprising a system for loading/unloading supports of metal parts, means of force-free machining for machining said metal parts and a system for controlling said force-free machining means, said machining machine defining a horizontal plane X-Y and a vertical axis Z orthogonal to the horizontal plane X-Y.

Each support comprises, at least on one side, a surface arranged to fix a plurality of metal parts previously produced by the LIGA process.

The corrective machining equipment comprises at least one corrective machining reference mark XYZ linked to a manufacturing reference mark X1Y1Z1 used during the production of metal parts by the LIGA process.

The corrective machining equipment comprises a recording system in said manufacturing reference frame X1 Y1Z1 of at least one target geometry and at least one predetermined reference position x1, y1, z1 specific to each positioned metal part on the support, said system for recording said target geometries and said positions x1, y1, z1 being arranged to cooperate with the system for controlling said force-free machining means.

The corrective machining equipment comprises a recognition system, for example a vision system, and a calculation unit making it possible to recognize, in the corrective machining reference frame, the 3D geometry and the positioning of the metal parts previously produced by LIGA method and to determine a correction of the geometry to be made in relation to the target geometry and to said recorded reference position x1, y1, z1, at least the calculation unit being arranged to cooperate with the control system of the means d machining without force.

Said system for controlling said force-free machining means comprises a positioning system for said force-free machining means arranged to, before corrective machining of each metal part, move and position said force-free machining means in the reference mark of corrective machining reference with respect to said metal part to be corrected and to carry out corrective machining as a function of said geometry correction, so as to obtain said target geometry.

In one embodiment, said force-free machining means comprise a transmitter arranged to emit an electromagnetic wave. In one embodiment, the transmitter is configured to emit an electromagnetic wave having a wavelength between 150nm and 1 mm, preferably between 200nm and 15pm, even more preferably between 300nm and 5pm.

Advantageously the transmitter is a laser.

In one embodiment, said laser is a femtosecond laser, configured to emit pulses having a duration of less than 900 femtoseconds, preferably less than 400 femtoseconds.

In one embodiment, at least one corrective machining positioning mark is provided on the support of metal parts and recognized by the vision system in the corrective machining reference mark, said corrective machining positioning mark being in connection with at least one manufacturing positioning mark from which the reference position x1, y1, z1 of each part in the manufacturing reference mark is defined.

In an alternative embodiment, at least one corrective machining positioning mark is provided on at least one of said metal parts and recognized by the vision system in the corrective machining reference mark, said machining positioning mark corrective being linked to at least one manufacturing positioning mark from which the reference position x1, y1, z1 of each part in the manufacturing reference mark is defined.

In one embodiment, the vision system is arranged to carry out a 3D geometry and positioning measurement with a precision of less than 10 pm, preferably less than 5 pm, more preferably less than 2 pm, in at least one of the 3 X, Y, Z axes.

In one embodiment, said support is arranged to carry at least two assemblies containing metal parts of different types.

In one embodiment, the machining machine comprises a system for releasing, after corrective machining, at least part of the metal parts from their support.

In one embodiment, said positioning system comprises a 5-axis optical system, arranged to cooperate with the control system of said force-free machining means, to be able to orient the electromagnetic wave emitted in the 3 dimensions X-Y-Z.

In one embodiment, said system for controlling said force-free machining means is arranged to machine at least a portion of the metal parts according to different machining steps. In one embodiment, each support is arranged to receive more than 10, preferably more than 100, preferably more than 1000, preferably more than 5000 metal parts, and said machining machine is adapted to be able to machine at least 5000 parts in less than 10,000 seconds.

In a second aspect the invention is carried out by a method of corrective machining of microtechnical metal parts previously produced by a LIGA process, said method comprising the different steps (A-F) consisting of:

A: provide, on a parts support, metal parts previously produced by a LIGA process;

B: equip yourself with corrective machining equipment as described and insert at least one of said part support into said machining machine;

C: record in a manufacturing reference mark used during the production of metal parts by the LIGA process a target geometry and at least one predetermined reference position x1, y1, z1 specific to each metal part positioned on said part support;

D: recognize, in at least one corrective machining reference mark linked to said manufacturing reference mark, the 3D geometry and the positioning of the metal parts, previously produced by the LIGA process, and determine a correction of the geometry to be made by relative to said target geometry and to said reference position x1, y1, z1 recorded using said vision system and said calculation unit;

E: execute corrective machining steps of said metal parts by said force-free machining means, which are, before the corrective machining of each metal part, moved and positioned relative to said at least one corrective machining reference mark by relative to said metal part to be corrected, in order to carry out the corrective machining as a function of said correction of the geometry determined in step D to obtain said target geometry;

F: release at least one of said metal parts from its support.

In one embodiment, the corrective machining positioning mark is provided on said support and recognized by the vision system in the corrective machining reference mark, said corrective machining positioning mark being linked to at least a manufacturing positioning frame from which the reference position x1, y1, z1 of each part in the manufacturing reference frame is defined. In variants, the corrective machining positioning mark provided on said part support has been transferred from the manufacturing positioning mark provided on the substrate in which the metal parts were produced by the LIGA process.

In one embodiment, said corrective machining positioning mark is produced on at least one surface of at least one metal part and recognized by the vision system in the corrective machining reference mark, said positioning mark d corrective machining being linked to at least one manufacturing positioning mark from which the reference position x1, y1, z1 of each part in the manufacturing reference mark is defined.

In one embodiment, said part support is a transfer film made at least partially from a polymer.

The invention is also obtained by a metallic microtechnology part, obtained by the process as described, and having at least one portion which presents, between the dimensions of the corrected part and the target geometry, a difference less than 2 pm, preferably less than 1.5pm.

In a variant, the metal microtechnology part, as described, comprises at least two surfaces of said metal microtechnology part which have been corrected with the method described.

Descriptions of the figures

The invention will be better understood on reading the detailed description of an exemplary embodiment made with reference to the appended figures among which:

- Figure 1 represents steps of a LIGA process and a transfer process onto a part support according to the invention;

- Figure 2 represents a parts support comprising metal parts produced by a LIGA process, according to the steps illustrated in Figure 1;

- Figure 3 represents a schematic diagram of a force-free machining machine;

- Figure 4 represents the diagram of part correction equipment comprising a force-free machining machine preferably comprising a femtosecond laser, a vision system and a calculation unit;

- Figure 5 represents a vertical section of a part produced by a LIGA process; - Figure 6 represents a laser beam directed on a microtechnical part according to Figure 5 with a view to performing a shape correction by material ablation using a force-free machining system;

- Figure 7 represents a laser beam directed on a microtechnical part, in a position to achieve a target diameter of an opening;

- Figure 8 represents a metal part produced by a LIGA process and whose shape and/or dimension and/or surface condition has been corrected using force-free machining;

- Figure 9 represents a multi-level micro-part, including holes, produced with the part correction equipment and the method according to the invention;

- Figures 10-12 illustrate metal parts produced by the part correction equipment and the method according to the invention;

- Figure 13 represents a part manufacturing base comprising metal parts produced by a LIGA process. Figure 13 also illustrates manufacturing positioning marks on the part manufacturing base;

- Figure 14 illustrates a manufacturing reference frame X1 -Y1 -Z1 based on three manufacturing positioning reference structures provided on a manufacturing base, such as a wafer, including the parts produced during the LIGA process;

- Figure 15 illustrates a machining machine corrective machining reference frame based on three corrective machining positioning reference structures that have been transferred from the manufacturing base to a part support.

- Figure 16 illustrates the coordinates of 4 particular points of an asymmetrical object in relation to a manufacturing reference mark X1-Y1 -Z1 linked to the LIGA process;

- Figure 17 illustrates the coordinates of 4 particular points of an asymmetrical object placed on a part support in relation to a corrective machining reference mark X-Y-Z of the machining machine;

- Figure 18 illustrates a plate 1 comprising parts to be machined and manufacturing positioning marks, the plate 1 being placed or fixed in or on a frame 220 of the machining machine. Figure 18 also illustrates a corrective machining reference mark XYZ of the machining system 200 and in which the corrective machining positioning marks coincide with the manufacturing positioning marks 20, 22, 24 of the insert 1; - Figure 19 illustrates a parts support 2 comprising parts to be corrected and which have been transferred from a manufacturing base 1 to said parts support 2. The parts support 2 is placed or fixed in or on a frame 220 of the machining machine 200. Figure 19 also illustrates a corrective machining reference mark XYZ of the machining machine 200 and which is based on the corrective machining positioning marks 30, 32, 34 of the part support 2 in connection with manufacturing positioning marks of a manufacturing base. Figure 20 illustrates a portion of a parts support comprising position markers near the metal parts on the parts support;

- Figure 21 shows a substrate comprising metal parts produced by a LIGA process;

- Figure 22 represents a flexible parts support comprising metal parts produced by a LIGA process.

Description of embodiments of the invention

The invention relates to a method for corrective machining of small metal parts previously produced by a LIGA process. The process makes it possible to produce very high precision metal parts, i.e. having surfaces, dimensions and shapes, which are defined with precisions of less than 2 pm, or even less than 1 pm.

Although a preferred application of the invention concerns the field of watchmaking, it is not limited to this field and can be applied to any field which benefits from small metal parts which have openings and/or surfaces. machined such as curved surfaces or surfaces defined by a polygon in at least one section of said metal part.

For example, the dimensions of metal parts used in watch mechanisms are very small and it is very difficult to machine them precisely and at low costs and at high speed. The maximum outer diameter of these parts is typically between 0.5 and 3 mm, and the typical thickness is between 0.05 mm and 1 mm.

It is known that it is very difficult to load and unload individual microtechnology parts very quickly in a machining machine in order to ensure the rate allowed by machining. Standard methods use vibrating bowl loading or vision-guided flexible feeding systems that directly load micro-engineered parts into clamp fixtures, allowing perfect positioning of small metal parts before machining. These methods are very difficult to develop to achieve high levels of reliability and autonomy. Furthermore, they are unable to reach very high loading/unloading rates (we are talking about rates between 0.5 seconds and 1 second per part).

Producing metal parts whose desired geometry is achieved with very high precision, typically of the order of a micrometer, by methods which are based on machining by applying a force requires machining part by part which is very expensive and does not always provide the required precision.

The equipment and method of the invention propose a method based on carrying out a correction, without applying force, to the dimensions and/or shapes of parts produced by the LIGA process. It is understood here that the term “force-free” means machining without direct contact between a machining tool and the parts to be machined, for example by the use of lasers.

The correction process can be carried out directly on a manufacturing base also defined as a wafer, on which the parts 10, 10' were produced by the LIGA process. This is illustrated in Figure 18.

In another mode of execution, the correction process is carried out on parts produced by LIGA which have been transferred to a part support 2. As described later, the transfer can be done by a polymer film or by another technique of transfer.

In the present description of the invention it is understood here that the term “machining” means a correction of shape and/or dimension of at least a portion of a part at least partially previously carried out by the LIGA process. The term “machining” also includes a simple correction of the 3D shape of the parts without necessarily removing material from the parts.

In the present description, “force-free machining” is called unconventional machining in which there is no mechanical action transmitted by direct contact and force between a tool and the part, unlike conventional machining where there is a direct contact between the tool and the workpiece and in which significant cutting forces are involved. Force-free machining is therefore machining without direct contact between the part to be machined and a machining tool which would be likely to exert force or stress on said part. Force-free machining is machining with a machining force less than a Newton (N) or a specific cutting pressure less than N/mm2.

Corrective machining equipment is defined as a machining system that corrects a previously defined shape. For example, the system can be arranged to correct the dimension of an opening or a part diameter. Corrective machining equipment does not make a shape starting from a block of material of any shape, such as a cubic shape to make a cylinder, but it only corrects a shape previously made by the LIGA process. In the case of a cylinder including a hole, the machining system will only be designed to correct the diameter of the hole and/or the external diameter of the cylindrical part. There are two scenarios for correction machining:

I) in a first case the corrective machining machine executes the correction directly on parts on the manufacturing basis which has been introduced into the machine.

II) in a second case the corrective machining machine carries out the correction on parts which have been transferred, with the manufacturing positioning marks 20-24, on a part support introduced into the corrective machining machine.

Definitions of manufacturing and corrective machining reference marks X-Y-Z, X1-Y1-Z1 and manufacturing and corrective machining positioning marks:

- The manufacturing reference mark X1Y1Z1 is defined by virtual axes X1, Y1, Z1 which are defined for example on the manufacturing base used in the LIGA process. A coordinate system x1, y1, z1 defines the position of the parts in said manufacturing reference frame X1Y1Z1.

- The corrective machining reference frame XYZ is advantageously defined by the virtual axes X, Y, Z which are defined by the machining machine 200. A coordinate system x, y, z defines the position of the parts in said frame corrective machining reference XYZ.

It is understood that the corrective machining and manufacturing reference marks X-Y-Z, respectively X1 -Y1 -Z1, are centered on a virtual reference center RC provided on the machining machine, RC’ planned in relation to the LIGA process. For example, the axes X, Y, and example a cross shape. Corrective machining and manufacturing reference marks XYZ, X1Y1Z1 are shown in Figures 14-19.

- A manufacturing positioning mark 20-24 is defined by at least one structure produced during the LIGA process and makes it possible to define in the manufacturing reference mark a relative reference position, specific to each metal part 10, 10' positioned on its manufacturing base 1. A benchmark can be a point structure or a structure that has a 2D shape like a cross. If the markers are point structures, at least 3 markers 20-24 are required. The relative position of the parts to be corrected in relation to said manufacturing references 20-24 is known precisely by the masks used during the LIGA process. The relative precision is of the order of 1 -2 pm. The manufacturing positioning marks 20-24 can advantageously be used to define the manufacturing reference mark X1Y1Z1.

- A corrective machining positioning mark 30-34, 40, 47 is defined by at least one structure produced during the transfer of the parts 10, 10' produced by LIGA on the support and which is read by the machining machine for define its position in the corrective machining reference frame, which makes it possible to determine, in the corrective machining reference frame of the machining machine 200, a position x, y, z. Identifying the corrective machining position marks in the corrective machining reference mark makes it possible to determine, for example, whether the transfer film has been distorted, which could result in the relative positions of the position marks corrective machining 30-34, 40-47 are different from the relative positions of the manufacturing positioning marks 20, 22, 24 in the manufacturing reference mark.

If the correction of the parts to be made is carried out directly on the manufacturing plate 1, the corrective machining reference mark and the manufacturing reference mark may be confused and are based on the relative positions of the manufacturing positioning marks 20- 24 which are confused with the corrective machining positioning marks. The corrective machining positioning marks can advantageously be used to define the corrective machining reference mark XYZ.

The equipment and method of the invention make it possible to carry out a correction of the desired dimensions and/or shape by said force-free machining, also defined as “force-free correction”. The metal parts are produced in batches using a LIGA technique and with an average precision, typically +/- 2 microns, characteristic of the LIGA process, and are finalized by final machining without applying force.

It is understood that all the embodiments and variants of the equipment of the invention can be combined with each other according to any technically compatible combination. It is also understood that all embodiments and variations of the process of the invention can be combined with each other according to any technically compatible combination.

The equipment and method of the invention may comprise at least one of the following force-free machining means:

- machining by emission of an electromagnetic wave, for example a beam of light such as a laser beam;

- plasma machining, preferably directional plasma;

- machining by microwaves, preferably directional microwaves;

- machining by electrochemical process, preferably local electrochemical attack (ECM). The ECM process is a machining method generally used for deburring, hollowing, polishing or drilling. Electrochemical machining requires two elementary components: the electrolyte and electric current. The “electrolyte” is, for example, salt water which constitutes the conductor of the electric current;

- machining by magnetic effect;

- machining by beam of electrons, protons or neutrons;

- machining using an electric arc, for example by sinking electroerosion, commonly also called EDM (English term meaning “electrical discharge machining”);

- wire machining and electroerosion.

The various force-free machining methods do not necessarily have to remove material. For example, by induction a portion of a part can undergo deformation, such as a slight correction of the radius of curvature of a thin membrane.

It is understood that at least two machining means can be implemented, whether in operation at the same time or according to delayed machining times. For example, metal parts can first undergo radiation with an infrared flow in order to soften or deform a metal part 10, 10', followed by local machining by femto laser.

Description of the Equipment

More precisely, in a first aspect, the invention relates to equipment for corrective machining of metal parts 10, 10' of microtechnology produced previously by a LIGA process, comprising a machining machine 200. The machining machine 200 may comprise a loading/unloading system 300 of part supports 2 for metal parts 10, 10', machining means without force to machine said metal parts 10, 10' and a system for controlling said force-free machining means. As illustrated in an example in Figure 4, said machining machine 200 defines a horizontal plane XY and a vertical axis Z orthogonal to the horizontal plane XY.

Each part support 2 comprises, at least on one side, a surface 2a, 2b arranged to fix a plurality of metal parts 10, 10' previously produced by the LIGA process.

The corrective machining equipment always comprises a measuring system, preferably a vision system arranged to be able to recognize the positions of the manufacturing positioning marks 20-24 on said manufacturing base introduced into the machining system, and/ or corrective machining positioning marks 30-34 on the part supports 2 introduced into the machining machine.

This is illustrated in Figures 14 and 15.

Figure 14 illustrates the situation of manufacturing parts by LIGA on a manufacturing wafer 1, also defined as substrate. The 3 manufacturing positioning marks 20, 22, 24 define, on the plate 1, an orthogonal manufacturing reference mark X1Y1Z1 or, depending on the marks used, a manufacturing reference mark X1Y1Z1 which includes an angle a between the axes X1 and Y1. The direction Z1 is always perpendicular to the plane defined by the axes X1 and Y1. The center of the manufacturing reference mark can be defined anywhere on the wafer 1.

In the case of a transfer of parts to a parts support 2 illustrated in Figure 15, the three manufacturing positioning marks 20, 22, 24 are transferred identically to a parts support 2 to form three manufacturing positioning marks. corrective machining positioning 30, 32, 34 which define in the machining machine 200, a corrective machining reference mark XYZ. The vision system locates these three corrective machining positioning marks 30, 32, 34 in the corrective machining reference mark XYZ to deduce the position and orientation of the metal parts 10,10' in said machining reference mark patch XYZ.

Thus, position and orientation of the metal parts 10,10' are perfectly known in relation to the corrective machining reference mark XYZ and can be used for the correction operation.

For example, in an example illustrated in Figure 16, the position and orientation of an asymmetrically shaped part can be obtained by recognizing, in the manufacturing reference frame X1 Y1Z1, the coordinates of the 4 characteristic points A, B, C, D. Two points A, B define the 2D dimension maximum of the part, and two other points C, D define the minimum dimension of the part.

In the event of transfer, the corrective machining positioning marks 30-32 may have different distances from the manufacturing positioning marks 20-24. Also, the angles of the virtual axes a, a' defined by the corrective machining positioning marks 30-32 and the manufacturing positioning marks 20-24 may be slightly different as illustrated in Figures 14 and 15. This may have as an origin for example the contraction or elongation or twisting of the transfer film during transfer.

Also, the corrective machining positioning marks 30-32 and the manufacturing positioning marks 20-24 do not necessarily have to be aligned along virtual axes which are perpendicular. Fig.19 illustrates a parts support where the axes X1 and Y1 form an angle [3 which is different from 90°.

The relative position of the initial marks 20-24 can then be altered, for example by deformation of the transfer film. The vision system can recognize the relative position D30-32, D 30-34, D32-34 of the transferred marks. By comparing the new relative distances D30-32, D30-34, D32-34 with the initial manufacturing relative distances D20-22, D20-24, D22-D24, the system can recognize the deformation and make a correction to the reference values of the workpieces. It is assumed here that the film deforms in a uniform manner. Otherwise it is possible to characterize, depending on the mechanical constraints, either by measurements or by modeling the possible deformations and make appropriate corrections. This is possible to achieve because the same type of film would be used for the transfer of parts.

If there is no transfer to a part support, the corrective machining reference mark is confused with the manufacturing reference mark and the corrective machining positioning marks are confused with the positioning marks of manufacturing.

Thus, in all embodiments, the position and orientation of the metal parts 10,10' are perfectly known in relation to the corrective machining reference mark XYZ and can be used for the correction operation.

In order to create a more reliable measurement and corrective machining system, it is preferred to make corrective machining positioning marks closer to the parts, as illustrated by proximity marks 40-47 in Figure 20.

More precisely, the corrective machining equipment comprises a system for recording at least one target geometry and at least one predetermined reference position x1, y1, z1 specific to each metal part 10, 10' with respect to a manufacturing reference mark the manufacturing reference mark.

The corrective machining equipment comprises a vision system 120 and a calculation unit 130 making it possible to recognize, in the corrective machining reference frame XYZ, the 3D geometry and the positioning of the metal parts 10, 10' previously produced by LIGA method and to determine a correction of the geometry to be made in relation to the target geometry and to said recorded reference position x1, y1, z1, at least the calculation unit 130 being arranged to cooperate with the means control system machining without force. Advantageously a lighting system 140 of the parts 10, 10' or part of the part support 2 is adapted in the machining equipment, preferably adapted to the vision system 120 as illustrated in Figure 4. The system d The lighting can emit a 142 UV, visible or infrared beam which can be divergent, collimated or focused.

Said system for controlling said force-free machining means comprises a positioning system for said force-free machining means arranged to, before corrective machining of each metal part 10, 10', move and position said force-free machining means in the corrective machining reference mark with respect to said metal part 10, 10' to be corrected and to carry out the corrective machining as a function of said correction of the geometry, so as to obtain said target geometry. In Figure 4 said movement and positioning of the force-free machining means in a space XYZ is illustrated by the symbols AX, AY, AZ.

In a preferred embodiment, illustrated in Figure 3, the force-free machining means comprise a transmitter 100 arranged to emit an electromagnetic wave 110. In other embodiments, the transmitter 100 is a particle emitter such as electrons, protons or neutrons. In other embodiments, the transmitter comprises a generator of an electric and/or magnetic field, for example an induction coil. In other embodiments, the transmitter 100 is a part adapted to emit an electric arc. Of course, a transmitter can include at least two transmitters of different types.

Preferably, the transmitter 100 is configured to emit an electromagnetic wave 110 having a wavelength between 150nm and 1 mm, preferably between 200nm and 15pm, even more preferably between 300nm and 5pm. In one embodiment, the transmitter 100 is a laser, preferably pulsed, configured to emit a laser beam 110. The latest generation lasers with ultra-short pulses allow the controlled and precise removal of material. The proposed solution combines corrective machining by ultra-short wave laser on components previously manufactured by LIGA technology.

Advantageously said laser 100 can be a femtosecond laser, configured to emit pulses having a duration of less than 900 femtoseconds, preferably less than 400 femtoseconds. Machining a surface and/or internal hole of a metal part by laser, preferably a femtosecond laser, is very fast, and machining can be done in approximately 0.5 to 1.5 seconds depending on the dimensions of the openings to achieve. Typical opening diameters are between 0.05 mm and 2 mm.

Typical pulse durations of a pulsed laser 100 are preferably between 1000 fs and 40 fs.

Preferably, an emitter 100 can emit in the infrared with a wavelength between 800 nm and 1100 nm, ideally 1030 nm, or in the green with a wavelength between 500 nm and 540 nm, ideally 515 nm , or in the blue with a wavelength between 400 nm and 480 nm or in the ultraviolet with a wavelength less than 400 nm, ideally 343 nm.

Advantageously, the transmitter 100 is a femtosecond laser emitting a UV, green or infrared beam. A 343 nm UV femtosecond laser and a 515 nm green femtosecond laser can achieve a roughness of less than 50 nm on metal parts. In the case of an IR laser emitting a beam with a wavelength of 1030nm, a typical roughness is 100 nm or better.

In embodiments, the maximum energy per laser pulse is advantageously close to 2 mJ.

The power of the laser is typically 20 W, but must be adapted depending on the material of the metal parts 10, 10'.

One of the advantages of manufacturing microstructures by photolithography and electroforming is being able to manufacture a large number of parts on the same basic substrate.

Retouching can therefore be done when the metal parts 10, 10' are still positioned on the part support 2 in the same configuration as they had on the substrate 1 during the LIGA process. As the parts are positioned on said parts support 2 in an identical manner to the configuration of the substrate 1, there is no need for a system for feeding and orienting the metal parts 10, 10'. A movement system in the XY plane for the part support 2 or for the transmitter 100 is sufficient to be able to work a large number of metal parts 10, 10'.

Another advantage of this manufacturing process is that the positioning of each part 10, 10' on the part support 2 is perfectly known. This is not essential to the corrective machining equipment and method of the invention, but can be advantageously implemented in one embodiment. For example, the positioning of each part 10, 10', of each hole in parts, can be referenced. Preferably, the parts support 2 is a flexible support. The transfer of parts from substrate 1 on which parts 10, 10' are produced by LIGA onto a part support 2 is illustrated in Figure 1 and described in more detail in the paragraph relating to the process of the invention.

We can therefore preferably rely on this positioning to perfectly center the retouching by the transmitter 100 after an optical measurement of the location of the hole, for example. Retouching by micro-machining by the transmitter 100 is then facilitated, because the positions of the metal parts 10, 10' are perfectly known. In order to avoid high machining times, re-machining will only be carried out to bring the geometries into the correct dimensions. The geometry (the diameter in the frame of a hole, for example), will be sketched using LIGA technology. Laser remachining will only be used to complete the dimensions of the hole on the last microns and obtain the required verticality and precision.

The principle of re-machining is illustrated in Figures 5 to 8. Figure 5 illustrates a metal part 10 which comprises a hole 12 of which at least one vertical section does not have a uniform diameter and whose average diameter D0 does not have not the right value. A laser beam 110 is moved (Figure 6) to the predetermined location making it possible to correct (Figure 7) the diameter of the hole to its desired value D1 (Figure 8).

In one embodiment, illustrated in Figure 4, the corrective machining equipment comprises a loading/unloading system 300 of part supports 2.

Positioning marks

In one embodiment at least one corrective machining positioning mark is provided on said support 2 of metal parts 10, 10'.

These corrective machining positioning marks 30, 32, 34 are recognized by the vision system in the corrective machining reference mark XYZ of the machining machine. Each corrective machining positioning mark 30, 32, 34 is linked with a manufacturing positioning mark 20, 22, 24 from which the reference position x1, y1, z1 of each part 10, 10' in the manufacturing reference mark X1Y1Z1 is defined. The term "linked" means for example that the corrective machining positioning marks 30, 32, 34 are obtained on the part support 2 by identical transfer of the manufacturing positioning marks 20, 22, 24 provided on the plate 1.

Figure 13 illustrates a wafer-shaped substrate 1 comprising several manufacturing positioning marks 20, 22, 24, 26.

Figure 20 illustrates corrective machining positioning marks 40, 41, 42, 43, 44, 45, 46, 47 which come from a transfer of corresponding manufacturing positioning marks provided on the wafer 1. Advantageously, these corrective machining positioning marks 40, 41, 42, 43, 44, 45, 46, 47 are located near the parts 10, 10’, 10”, 10’” which are to be corrected.

The corrective machining positioning mark does not necessarily have to be on said part support 2. Indeed, in another embodiment the corrective machining positioning mark is provided on the machining machine 200.

In an advantageous variant, the corrective machining positioning mark is at least one alignment mark made on a surface of said support 2 of metal parts 10, 10'. The corrective machining positioning mark may for example consist of one or more alignment patterns, for example cross-shaped patterns.

In a variant, the corrective machining positioning mark is at least one alignment mark made on a surface of said part support 2, near each part 10,10'. In a variant, each metal part 10, 10', 10", 10'" has its own corrective machining positioning mark near it.

In a variant, the corrective machining positioning mark is an element of the metal part 10, 10'. As above, it is recognized by the vision system in the XYZ corrective machining reference frame. It should be noted that in the case of parts 10, 10' of symmetrical shape, such as cylinders, it is sufficient to know the coordinates x1, y1, z1 of the parts on the manufacturing plate 1 in the manufacturing reference mark X1Y1Z1.

In the case of asymmetrically shaped parts, you also need to know the orientation. In certain cases illustrated in Figure 16 and 17, it is sufficient to know the coordinates x1, y1, z1 of 4 characteristic points A, B, C, D of the parts 10, 10' in the manufacturing reference frame X1Y1Z1 without the need to 'a recording all around the room. In case of transfer to a part support 2 in the corrective machining reference frame XYZ, as illustrated in Figure 17, knowledge of the x, y, z coordinates of the transferred characteristic points A', B', C', Help ensure fast machining speed.

Of course, the equipment and the method of the invention can implement different corrective machining positioning markers, for example at least one marker on the part support and at least one marker on a frame which holds the part support. pieces.

Vision system(s)

In one embodiment, the vision system 120 is arranged to carry out a 3D geometry and positioning measurement with a precision of less than 10 pm, preferably less than 5 pm, more preferably less than 2 pm, in at least one of the 3 X, Y, Z axes.

Preferably the vision system 120 includes:

- a CCD sensor

- telecentric optics

- central TV lighting

- at least one calibration means

The vision system 120 preferably also includes suitable image processing means. For example, the vision and recognition system may include image processing means which take into account the diffraction effects encountered during the optical resolution of characteristics and small dimensions.

A vision system, including means of compensating for diffraction effects, makes it possible to achieve measurement and repeatability accuracies of ±0.2 um.

Advantageously, the focusing and the 3D movements of the beam 110 are carried out by an optical unit, for example an optical unit which may comprise a system for adapting the shape of a laser beam and an orientation of 3, 4 or 5 axes in space. For example, the focusing of the laser beam can be adapted during the correction operation of metal parts 10, 10'.

In an advantageous and preferred embodiment, the position measuring device is adapted to the positioning system of a laser 100. In this case the device for measuring the xyz position of the metal parts 10, 10' comprises a optical vision system 120 which is preferably attached to said laser 100, as illustrated in Figure 4. Figure 4 illustrates an example of an arrangement of such a vision system 120 comprising an image sensor adapted to form images in a horizontal plane XY and preferably an illumination system 140 adapted to emit an illumination beam 142. The xyz position measuring system can advantageously comprise a system for determining the vertical position z of the metal parts 10, 10'. Advantageously, such a system for measuring the vertical position is an optical system comprising a dynamic focusing system in the vertical direction Z. It is understood that the 2D visualization system can be arranged in order to make 2D measurements according to different predetermined vertical positions. . For example, different 2D images can be taken for different z positions. The system can also be adapted to provide 2D images for a certain vertical position. For example, the vision system can be moved in the vertical direction so as to visualize a predetermined surface, for example the upper face or the rear face of the metal parts 10, 10'. This makes it possible to increase the precision of the 3D xyz measurement of metal parts 10, 10'.

Advantageously, the x-y-z position measuring device is arranged to carry out a measurement with a precision of less than 20 pm, preferably 10 pm, more preferably 5 pm, and preferably less than 2 pm, in the 3 axes ,Y,Z.

Other embodiments

In an alternative embodiment, the force-free machining means comprise a transmitter and said positioning system comprises a 5-axis orientation system, arranged to cooperate with the control system of said transmitter 100. This makes it possible to orient the beam machining 110 issued in the 3 dimensions X,Y,Z. In a variant, the transmitter 100 is a laser and the orientation system includes an optical system in order to be able to orient the emitted beam 110 in space.

In variants of the invention, said system for controlling the force-free machining means can be arranged to machine at least a portion of the metal parts 10, 10' according to different machining stages. For example, part of the parts 10, 10' fixed on said part support 2 would need to have a height, defined in the Z axis, reduced by 3 pm and another part of the parts 10, 10' would require a correction of the height of only 1 pm.

Advantageously, a parts support 2 is arranged to receive more than 10, preferably more than 100, preferably more than 1000, preferably more than 5000 metal parts 10, 10', and said machining machine 200 can be adapted to be able to machine at least 5000 parts in less than 10000 seconds.

In one embodiment, not illustrated in the Figures, the machining machine 200 comprises a system for releasing, after their machining, at least part of the metal parts 10, 10' from their support 2.

In a particularly advantageous manner, the machining machine 200 comprises a machining program for machining a predetermined number of said plurality of metal parts 10, 10'. In variants, the machining program can make it possible to machine two sets of metal parts 10, 10' by two different lasers of the machining machine 200 or can make it possible to machine two sets of parts by two modes of operation. different operation of a transmitter such as a pulsed laser. These different modes of operation may consist of the use of different energies or powers, and/or by adjusting the numerical aperture of the laser beam.

In an alternative embodiment, the machining machine 200 includes a machining program for machining at least a portion of the metal parts 10, 10' according to different machining steps. For example, each part can be treated to make a hole, followed by an operation for processing an edge or a circumference of the metal part 10, 10'.

In one embodiment, the machining machine of the invention 200 may comprise at least two lasers which produce non-parallel beams. For example, a first femtosecond laser can be adapted to make apertures and another laser can be used to produce a beam that is not parallel to the beam of the first laser.

Advantageously, the machining machine 200 of the invention can comprise at least one multibeam optics, adapted to carry out simultaneous machining of several parts at the same time.

Process

The invention also relates to a process for corrective machining of microtechnology metal parts previously produced by a LIGA process, said process comprising the different steps (A-F) consisting of:

A: provide on a parts support 2 metal parts 10, 10' previously produced by a LIGA process; B: equip yourself with corrective machining equipment, as described, and insert at least one of said part support 2 into said machining machine 200;

C: record, in a manufacturing reference mark 10, 10' positioned on said parts support 2;

D: recognize, in at least one corrective machining reference mark XYZ, in connection with the manufacturing reference mark X1 Y1Z1, the 3D geometry and the positioning of the metal parts 10, 10', previously produced by LIGA, and determine a correction of the geometry to be made in relation to said target geometry and to said reference position x1, y1, z1 recorded using said vision system 120 and said calculation unit 130;

E: execute corrective machining steps of said metal parts 10, 10' by said force-free machining means which are, before the corrective machining of each metal part 10, 10' moved and positioned in the reference mark of corrective machining XYZ with respect to said metal part 10, 10' to be corrected, and to carry out the corrective machining as a function of said correction of the geometry determined in step D, so as to obtain said target geometry;

F: release at least one of said metal parts 10, 10’ from its support 2.

In another embodiment, during said step A, the parts support 2 is replaced by the manufacturing plate 1 comprising the metal parts to be corrected. In this case, the corrective machining and manufacturing reference marks are confused, and the corrective machining and manufacturing positioning marks are also confused.

In an advantageous embodiment, the positioning mark of the corrective machining provided on said support 2 was transferred from the substrate 1 in which the metal parts 10, 10' were produced by the LIGA process from a manufacturing positioning mark.

In this embodiment, the corrective machining positioning mark 30, 32, 34, 40-47 is provided on said support 2 and recognized by the vision system in the corrective machining reference mark XYZ, said reference mark corrective machining positioning 30, 32, 34, 40-47 being linked to at least one positioning mark of manufacturing 20, 22, 24, 26 from which the reference position x1, y1, z1 of each part in the manufacturing reference frame X1Y1Z1 is defined.

In one embodiment, the corrective machining positioning mark 30, 32, 34, 41 -47 has been transferred from the manufacturing positioning mark 20, 22, 24, 26 provided on the substrate 1 in which the metal parts 10, 10' by the LIGA process.

Once the metal parts 10, 10' loaded and referenced on the X-Y-Z table of the machining machine 200, the rate of corrective machining of the metal parts 10, 10' arranged on a parts support 2 is dictated by the corrective machining time, for example by the corrective machining time of the hole - typically 0.5 to 1.5 sec - plus the time of moving the table from one metal part 10, 10' to another. The corrective machining time is typically 0.3 to 1 second depending on the size and the distance between each metal part 10, 10'. For 10, 10' parts with an external diameter of 0.9 mm, more than 8,000 10, 10' metal parts can be arranged on a round support of 150 mm in diameter. Loading and unloading part supports 2 is extremely easy, and even if it is not fast, the time is divided by the number of parts 10, 10' per support 2. An automatic loading system for part supports 2 allows the machining machine to operate completely autonomously for very long periods, despite a cycle time for corrective machining of the parts which is typically around 1 second.

In a typical example, the vision system 120 proceeds by taking a picture of each of the metal parts 10, 10' individually. In an advantageous example, in order to reconstruct the x-y-z position of all the metal parts 10, 10', the vision system 120 proceeds by successively taking pictures of 10 to 15 metal parts. In a variant of the method, during step E, the positioning of the force-free machining means 100, relative to said metal parts 10, 10', is done by a movement in a plane X-Y or in space X-- Z of said force-free machining means 100.

In another variant, during step E, the positioning of the force-free machining means relative to said metal parts 10, 10' is done by moving said part support 2.

It is also possible that, during step E, the positioning of the force-free machining means is done by moving said transmitter 100 and also said part support 2. These two movements do not necessarily have to be simultaneous. In one embodiment, step D of recognizing the geometry and position of the metal parts 10, 10' is carried out successively for all the metal parts 10, 10' just before their machining.

In a variant, at least one step of cleaning the parts 10, 10' is carried out between two corrective machining cycles of the metal parts 10, 10'.

In one mode of execution, the corrective machining step E comprises at least the correction of an opening 10a, 10b, 10c, 12 in at least one of said plurality of metal parts 10, 10'.

The part supports 2 can be of all shapes, typically rectangular, square or circular. Preferably, the support is a flexible film made from a polymer. In this case the film is held in a frame as support. The support is for example an adhesive film commonly used in the microelectronics industry and known by the English term “tape”. This type of film is used in this industry to enable sawing, machining or thinning of wafers, for example.

The parts support 2 can be a transparent glass support, for example made of borosilicate glass. The parts support 2 can be a wafer, commonly called a wafer in English, made of semiconductor material, metal alloy, ceramic material or other material.

In one embodiment, the parts support 2 may be a combination of the supports described above.

If the part support 2 is a polymer film, the machining of the parts 10,10' can be accompanied by drilling of the support 2. For example, when widening a hole, a laser can pierce the parts support 2 and thus more easily evacuate the metal removed from the parts 10, 10'.

If the parts support 2 is made of a hard material and includes an adhesion film, the parts supports 2 can be pierced. By using part supports 2 which are drilled, with openings provided at each position intended to position the metal parts 10, 10', it is possible to facilitate the corrective machining of the parts as well as their release. Indeed, during the corrective machining of the parts (step E of the process described) the fact of having an opening under each metal part makes it possible to easily pass through the adherent film of the part support 2 which will be pierced, forming an opening in the film member. Thus, the material of the metal part 10, 10' as well as that of the adhesive film can be evacuated through the opening of the hard part support 2 which is located under the metal part 10, 10'. This evacuation can be done by suction or by a pressurization system. Said adhesion film also ensures that the metal parts cannot move or vibrate during laser machining. A simple placement of parts could not be used during a transfer to a parts support.

In variants, said adhesion film may be a semi-adherent or adhesive layer such as a double-sided adhesive strip, for example a polymer film, which is fixed on a parts support 2. Certain types of adhesive films used in microtechnology ensure adhesion strength without having to use glues. These films are commonly called “blue tapes” and known to those skilled in the art of microtechnology.

Advantageously, the adhesion of a transfer film is typically between 0.50 and 4.50 N/25mm

In embodiments the transmission, for wavelengths between 400nm and 3pm is at least 25%, preferably at least 50% and more preferably at least 75%.

In embodiments, the thickness of said transfer film is between 0.80 and 1.25 mm.

In embodiments the variation in the thickness of said transfer film is less than 10% of its thickness, preferably less than 5% of its thickness, the thickness being defined as the average thickness of said transfer film.

In one embodiment, machining can also be done by directing the laser from the opposite side of the parts which are arranged on the part support 2.

In one embodiment, openings can be provided in the adhesion film under each part.

Advantageously, in a variant, a force-free machining system, using a laser 100, may comprise optics delivering more than one laser beam, typically 2, 4, 9, 16 or more beams. This allows the simultaneous machining of several 10, 10’ metal parts at the same time.

It is understood that the multiple beams are of Gaussian shape, but can have modifications of numerical aperture and working distance due to the diffractive optical element -DOE- depending on the desired function of the optical beam which is directed on the part to be machine. It is here referred to the following publication: https://www.pulsar-photonics.de/en/optical-modules/multibeamscanner-mbs/

With a suitable optical element, it is possible to carry out almost any correction of 10, 10' parts ensuring great homogeneity and high overall efficiency. By combining a multibeam system with at least one scanner galvanometric, it is possible to generate a large number of treatment points in the treatment plan, which are moved simultaneously on the metal part 10, 10' by said scanner.

The company Pulsar Photonics for example, whose reference is found under the website https://www.pulsar-photonics.de/, offers a solution of a multi-beam scanner for multi-beam laser processing. Such a system comprises at least one beam scanner based on a galvano system. Selectable beam splitting with a multi-beam module generates a fixed beam arrangement in the scanning system work plane. This approach makes it possible to multiply the speed of the process in the production of periodic structures.

Using a diffractive beam splitter, the power of the laser system can be divided into up to 100 partial beams and more. Typical beam distributions can be, without limitation: 2x2, 4x4, 8x8, where n x m or n and m are different numbers. It is understood that laser beams may be different, for example they may have a different focal length.

The use of a multi-beam system allows efficient parallel production of identical structures in a single step.

It is thus possible to overcome the power limitations, essentially of physical origin, of many "ultra short draw" processes and thus to considerably increase the efficiency of the processes.

Areas of application are drilling, parallel processing of several components or general process parallelization.

The release of the metal parts 10, 10', fixed to the parts support 2 can be done in various ways, for example by solvents or via heat treatment or UV exposure. Exposure to radiation can, for example, cause the release of gas at bonding interfaces. Release can also be achieved by exposure to heat or flashes of infrared radiation. Said UV and/or infrared radiation can be produced by pulsed power sources.

In variants, step F of releasing the parts can be done in various ways:

- by application of vibration and/or shock;

- by mechanical scraping;

- by the use of a “pick and place” arm or robot;

- by liquid and/or ultrasonic means;

- by blowing with air or other gas. Transfer technique on part support 2 after LIGA process

The technique of transferring 10.10' parts produced by the LIGA process onto a part support 2 is now described in detail and is referred to in Figure 1.

The advantage of the LIGA technique is to produce metallic microcomponents with very high precision in X and Y and with a thickness of up to several millimeters. It is also possible to apply the process in several stages to obtain a microcomponent at several levels, each level being built on the previous one.

The positioning of the metal parts 10, 10' in relation to each other as well as in relation to reference marks is known, because the parts remain throughout the process in the same position as their original position on the wafer.

The wafer 1, also defined as a substrate, is generally a support plate of glass, metal or silicon on which a conductive layer produced by an evaporation of chromium and gold, for example, is deposited. In the case where the substrate is naturally conductive, it is not necessary to deposit a conductive layer. For the remainder of the description, the “conductive substrate” is therefore either the naturally conductive substrate, or the substrate with a conductive layer on its surface. On the conductive substrate is deposited a layer of photosensitive resin, preferably of the negative type sensitive to UV ultraviolet rays, hereinafter called “photoresist”, typically from the SU-8 family of MicroChem Corporation. It is also possible to use dry photosensitive resin, that is to say without solvent or with very low levels of solvent. Alternatively, the photoresist could be of the positive type.

This photoresist layer is polymerized after selective irradiation. In the particular case of a negative type photoresist, the irradiated parts are polymerized while the non-irradiated parts are not polymerized. If necessary, the photoresist layer is flattened before irradiation.

Once developed, that is to say after elimination of the non-polymerized photoresist parts, a photoresist mold 3 is obtained. This mold 3 is illustrated in Figure 1, step 1 a and the parts of photoresist eliminated reveal cavities. On a single-level mold, these cavities reveal the conductive substrate 1.

The next step consists of filling the mold 3 with photoresist according to an electroforming operation, the conductivity of the conductive substrate 1 allows a metal deposition in the cavities of the mold 3 and when the level defined by the polymerized layer of the mold 3 is reached, the metallization is interrupted. We see in the figure of step 1 b, a slight overflow of the metal part 5. It is customary, but not necessary, to extend the electroforming once the upper level of the mold 3 has been reached to ensure that all cavities are filled. Figure 1 b illustrates the state in which the assembly is at the end of these operations. The electroformed metal layer forms a plurality of metal portions 5 linked together by the photoresist mold 3 and secured to the conductive substrate 1.

In this description, the face of the metal parts corresponding to the free side of the metallization by electroforming is called "external face". The “internal face” is that which, during metallization, is in contact with the conductive substrate 1. Metallization by electroforming creates metal portions 5 with a raw external face 5a and a raw internal face 5b. They are called "raw" because they are a direct result of electroforming, either unmachined or polished.

A first machining step is carried out on the raw external face 5a of the microparts to obtain the machined external face 5c of the metal portions 5 in a desired state. The sides of the metal portions 5 correspond to the vertical part of the metal portions 5 in contact with the mold 3 during the electroforming phase. The height of the metal portions 5 is at this stage approximate. The result is illustrated in step 1 c allowing you to see the machined external face 5c of the metal portions 5.

The next step consists of eliminating the photosensitive resin mold 3 by chemical attack. The conductive substrate 1 will remain integral with the plurality of metal portions, as illustrated in step 1 d.

The next step is the application of a binder resin 4. This resin will cover the machined external face 5c and the sides of the metal portions 5 and fill the cavities left free by the elimination of the mold 3, i.e. say being in contact with the substrate driver 1. This binding resin 4 will also exceed the height of the metal portions as illustrated in step 1 e.

Next comes the preparation of the assembly by lowering and flattening the binder resin 4 to form a flat reference surface 4’ parallel to the conductive substrate 1. The result is illustrated in step 1f. It should be noted that the lowering of the binder resin 4 is done so that the machined external face 5c of the metal portions 5 remains covered with binder resin 4. This assembly is released from the conductive substrate 1 by machining the latter or any other method of releasing the conductive substrate 1. All of the metal portions 5 and the binder resin 4 form a rigid whole. The result is shown in Figure 1g.

Said binder resin 4 can be, for example, a hot melt glue based on natural shellac and a mineral filler which can be in the form of powder or in pieces. The cement product B67 or MelBo325 from Stettler Sapphire (internet ref.: https://www.stettlersapphire.ch/index.php/fr/), for example, can be used.

During the same machining operation of the conductive substrate 1, or a separate operation, the raw internal face 5b of the metal portions is machined to obtain the machined internal face 5d. The machining operation will reduce the height of the assembly until a desired height of the metal parts 10, 10’ to be produced is reached. The result is visible at step 1 h of Figure 1.

A transfer film, which is the part support 2, is applied to the machined internal face 5d of the metal portions 5 (see step 1 i). Once the transfer film 2 is in place, the binder resin 4 can be removed by dissolution for example. Thus the metal portions 5 form the metal parts 10, 10' which will subsequently undergo a correction of dimensions or shape according to the force-free machining process as described in this document. The metal parts 10, 10' are linked together by the transfer film acting as part support 2 (see step 1j, Figure 1). The metal parts 10, 10' thus find themselves in the same position in the X-Y plane as during the manufacture of the photoresist mold as well as all the other steps in which the substrate 1 was present.

It is also understood that the force-free machining equipment can be adapted to carry out a first corrective machining cycle and that the metal parts 10, 10' are finished by another process such as a mechanical or chemical process. For example, pierced metal parts 10, 10' can be treated internally or outside the machining machine 200 in order to clean them or for a plasma smoothing treatment carried out on all the parts 10, 10' on a parts support 2. It is also understood that, in one embodiment, the machining machine 200 may include means for depositing a coating on the parts 10, 10' before or after their machining.

In an advantageous embodiment, all the parts 10, 10' can undergo a first corrective machining step which can be a surface preparation step carried out for example by said femtosecond pulse laser. In a variant, all of the metal parts 10, 10' can undergo a cleaning step and/or deposition of a layer.

Depositing a layer before corrective machining with the femtosecond laser makes it possible to better delimit the corrective machining zone. This layer can be removed after the corrective machining process.

It is understood that the corrective machining conditions can be adapted depending on the location (i.e. drawer) of a cassette system 300 of the corrective machining equipment of the invention. Thus, a first drawer may comprise a support 2 with parts 10, 10' in which a hole must be corrected and another drawer may comprise another support with parts whose surface must be corrected or on which a predetermined shape must be executed.

In one embodiment, the parts support 2 in a drawer of a cassette system 300 can undergo several corrective machining cycles. For example, during a first cycle all the parts 10, 10' are processed to correct a hole and during a second loading of part supports 2 into the machining machine 200, all the part supports 2 can be passed through the machining machine in order to correct for example an edge of the parts 10, 10'.

In one embodiment, during at least a second machining cycle, at least one other type of laser can be used. This laser may be another femtosecond laser.

Depending on the application it is understood that the parts 10, 10' do not necessarily have to be arranged in a homogeneous manner on their parts support 2. For example, the metal parts 10, 10' can be arranged in a shaped arrangement disk or rectangle.

In one embodiment the parts 10, 10' can be fixed on both sides of a parts support 2, for example by temporary gluing. A double-sided arrangement (not illustrated in the Figures) makes it possible to increase, for example by a factor of 2, the speed of corrective machining by the machining machine 200 of the invention. It is understood that an inspection system can be used to track the dimensions of the corrected parts and to adapt the corrective machining parameters of the laser machine to enable autonomous and more precise production.

Metal parts made

There is no limitation in shape or 3D dimension of the metal parts 10, 10' produced by the equipment and the method of the invention.

The metal parts 10, 10' are typically millimeter or micrometer in size. Femtosecond laser machining allows very high machining accuracies, typically less than ±1 pm. Surface roughness in cutting mode can reach roughness of 50nm or lower.

In one embodiment, a metallic microtechnology part 10, 10' is obtained by the method described and comprises at least one portion which presents, between the dimensions of the corrected part and the target geometry, a difference of less than 2 pm, preferably less than 1.5 pm.

In another embodiment at least two surfaces of said metal microtechnology part 10, 10' have been corrected with the method according to the invention.

Figures 9-12 illustrate metal parts produced by the part correction equipment and the method according to the invention.

Figure 9 represents a metal part 10 comprising structures made in 3 different planes P1, P2, P3 and comprising openings 10a, 10b, 10c.

Figure 10 shows a watchmaking anchor produced according to the process of the invention.

Figure 11 shows a clockwork toothed wheel produced according to the method of the invention.

Figure 12 shows a connector part produced according to the method of the invention. The part 10 illustrated in Figure 12 may include at least one surface 10e, 10d which has been corrected with the method and the machining equipment according to the invention.

Example of application and configuration of corrective machining equipment for metal parts (10, 10') of microtechnology according to the invention.

The following example shows an application case with metal parts 10, 10' on part supports 2 having a diameter 150 mm. For 10, 10' parts with a diameter of 0.9 mm, approximately 8,000 parts can be produced on a support of parts 2 which is preferably a wafer and achieve corrective machining rates of around 1 second, that is to say between 8 and 10 times lower than what could be obtained with a conventional approach.

In a preferred configuration, corrective machining equipment includes:

- a loading/unloading system of at least 25 part supports 2;

- a measuring system 120 capable of measuring very precisely the position x, y, z of each metal part 10, 10' in the corrective machining reference mark XYZ;

- a machining machine 200 including a femtosecond laser.

In the example, 8,000 metal parts 10, 10' can be aligned on a single parts support 2. The loading and unloading system is preferably a "cassette" type system comprising a plurality of drawers, each drawer being adapted to contain a single wafer.

The different operations can take the following times:

- laser machining per part: 0.5 to 0.6 sec;

- repositioning of the X-Y table: 0.3 sec;

- charging and discharging by part support 2: 120 sec;

- time limits for measurements: 60 sec.

This indicates a time for corrective machining and measuring parts 10, 10' typically below 2 seconds, more precisely 0.92 sec for the example described.

In the example of execution, the cassette system will therefore include a maximum of 25x8000 parts to be machined, therefore a maximum of 200,000 10, 10' parts.

The method and the machining machine 200 of the example make it possible to insert the part support 2 under a femtosecond laser 100 and to correct all the parts 10, 10' on a single part support 2. When all the parts 10 , 10' fixed on a support of parts 2 are corrected, it is unloaded towards a drawer of a cassette system 300 associated with the machining machine 200 and corrective machining of the metal parts fixed on a second support is carried out of pieces 2', 2”, 2'” and so on.

Claims

1. Equipment for corrective machining of metal parts (10, 10') of microtechnology previously produced by a LIGA process, comprising a machining machine (200) comprising a loading/unloading system (300) of supports (2) of metal parts (10, 10'), force-free machining means for machining said metal parts (10, 10') and a system for controlling said force-free machining means, said machining machine (200) defining a horizontal plane X-Y and a vertical axis Z orthogonal to the horizontal plane X-Y, characterized in that

- each support (2) comprises, at least on one side, a surface arranged to fix a plurality of metal parts (10, 10’) previously produced by the LIGA process;

- the corrective machining equipment comprises at least one corrective machining reference mark (XYZ) linked to a manufacturing reference mark (X1Y1Z1) used during the production of the metal parts (10, 10') by the LIGA process;

- the corrective machining equipment comprises a recording system in said manufacturing reference frame (X1Y1 Z1) of at least one target geometry and at least one specific predetermined reference position (x1, y1, z1) to each metal part (10, 10') positioned on the support (2), said system for recording said target geometries and said reference positions (x1, y1, z1) being arranged to cooperate with the control system of said means d machining without force;

- the corrective machining equipment comprises a vision system (120) and a calculation unit (130) making it possible to recognize, in the corrective machining reference frame (XYZ), the 3D geometry and the positioning of the metal parts (10, 10') carried out previously by the LIGA process and to determine a correction of the geometry to be made in relation to the target geometry and to said recorded reference position (x1, y1, z1), at least the calculation unit being arranged to cooperate with the force-free machining means control system;

- said system for controlling said force-free machining means comprises a positioning system for said force-free machining means arranged to, before corrective machining of each metal part (10, 10'), move and position said means of machining without force in the reference corrective machining reference (XYZ) with respect to said metal part (10, 10') to be corrected and to carry out corrective machining as a function of said geometry correction, so as to obtain said target geometry. Corrective machining equipment according to claim 1, characterized in that said force-free machining means comprise a transmitter (100) arranged to emit an electromagnetic wave. Corrective machining equipment according to claim 2, characterized in that the transmitter (100) is configured to emit an electromagnetic wave having a wavelength between 150 nm and 1 mm, preferably between 200nm and 15 pm, even more preferably between 300 nm and 5 pm. Corrective machining equipment according to claim 3, characterized in that the transmitter (100) is a laser. Corrective machining equipment according to claim 4, characterized in that said laser (100) is a femtosecond laser, configured to emit pulses having a duration of less than 900 femtoseconds, preferably less than 400 femtoseconds. Corrective machining equipment according to one of claims 1 to 5, characterized in that at least one corrective machining positioning mark (30, 32, 34, 40-47) is provided on said support (2) of metal parts (10, 10') and recognized by the vision system in the corrective machining reference mark (XYZ), said corrective machining positioning mark (30, 32, 34, 40-47) being linked with at least one manufacturing positioning mark (20, 22, 24,26) from which the reference position (x1, y1, z1) of each part in the manufacturing reference mark (X1Y1Z1) is defined. Corrective machining equipment according to one of claims 1 to 5, characterized in that at least one corrective machining positioning mark (30, 32, 34) is provided on at least one of said metal parts (10, 10 ') and recognized by the vision system in the corrective machining reference mark (XYZ), said corrective machining positioning mark being linked to at least one manufacturing positioning mark from which the position ( x1, y1, z1) reference of each part in the manufacturing reference mark (X1Y1Z1). Corrective machining equipment according to one of claims 1 to 7, characterized in that the vision system is arranged to carry out a 3D geometry and positioning measurement with a precision less than 10 pm, preferably less than 5 pm, more preferably less than 2 pm, in at least one of the 3 axes X, Y, Z. Corrective machining equipment according to one of claims 1 to 8, characterized in that the support (2) is arranged to carry at least two assemblies containing metal parts (10, 10') of different types. corrective machining according to one of claims 1 to 9, characterized in that the machining machine (200) comprises a system for releasing, after their corrective machining, at least part of the metal parts (10, 10') from their support (2). . Corrective machining equipment according to one of claims 2 to 10, characterized in that said positioning system comprises a 5-axis optical system, arranged to cooperate with the control system of said force-free machining means (100), to be able to orient the electromagnetic wave (110) emitted in the 3 dimensions XYZ. . Machining equipment according to one of claims 1 to 11, characterized in that said system for controlling said force-free machining means (100) is arranged to machine at least a portion of the metal parts (10, 10') according to different machining stages. . Corrective machining equipment according to one of claims 1 to 12, characterized in that each support (2) is arranged to receive more than 10, preferably more than 100, preferably more than 1000, preferably more than 5000 metal parts (10, 10'), and in that said machining machine (200) is adapted to be able to machine at least 5000 parts in less than 10000 seconds. . Method for corrective machining of microtechnical metal parts (10, 10') previously produced by a LIGA process, said method comprising the different steps (AF) consisting of:

A: provide, on a parts support (2), metal parts (10, 10’) previously produced by a LIGA process,

B: equip yourself with the corrective machining equipment according to one of claims 1 to 14 and insert at least one of said part support (2) into said machining machine (200);

C: record in a manufacturing reference mark (X1Y1Z1) used during the production of the metal parts (10, 10') by the LIGA process a target geometry and at least one position (x1, y1, z1) of its own predetermined reference to each metal part (10, 10') positioned on said part support (2);

D: recognize, in at least one corrective machining reference mark XYZ), in connection with said manufacturing reference mark (X1Y1Z1) the 3D geometry and the positioning of the metal parts (10, 10'), previously produced by the LIGA process, and determine a correction of the geometry to be made in relation to said target geometry and to said reference position (x1, y1, z1) recorded using said vision system (120) and said computing unit (130);

E: execute corrective machining steps of said metal parts (10, 10') by said force-free machining means (100), which are, before the corrective machining of each metal part (10, 10'), moved and positioned relative to said at least one corrective machining reference mark (XYZ) relative to said metal part (10, 10') to be corrected, in order to carry out the corrective machining as a function of said correction of the geometry determined at l step D to obtain said target geometry;

F: release at least one of said metal parts (10, 10’) from its support (2).

15. Method according to claim 14, characterized in that the corrective machining positioning mark (30, 32, 34, 40-47) is provided on said support (2) and recognized by the vision system in the reference mark corrective machining reference (XYZ), said corrective machining positioning mark (30, 32, 34, 40-47) being linked to at least one manufacturing positioning mark (20, 22, 24, 26) to from which the reference position (x1, y1, z1) of each part in the manufacturing reference frame (X1Y1Z1) is defined.

16. Method according to one of claims 14 and 15, characterized in that the corrective machining positioning mark (30, 32, 34, 41 -47) has been transferred from the manufacturing positioning mark (20, 22, 24, 26) provided on the substrate (1) in which the metal parts (10, 10') were made by the LIGA process.

17. Method according to claim 16, characterized in that said transfer is carried out by means of an adherent layer.

18. Method according to claim 17, characterized in that the adherent layer is a polymer film.

19. Method according to claim 14, characterized in that said at least one corrective machining positioning mark (30, 32, 34) is provided on at least one of the metal parts and recognized by the vision system in the reference mark. corrective machining reference (XYZ), said corrective machining positioning mark being linked to at least one positioning mark of manufacturing from which the reference position (x1, y1, z1) of each part in the manufacturing reference frame (X1Y1Z1) is defined.

20. Method according to one of claims 14 to 18, characterized in that said part support (2) is a transfer film made at least partially from a polymer.

21. Metallic microtechnology part (10, 10'), obtained by the method according to one of claims 14 to 20, and having at least one portion which presents, between the dimensions of the corrected part and the target geometry, a deviation less than 2 pm, preferably less than 1.5 pm. 22. Metal microtechnology part (10, 10') according to claim 21, characterized in that at least two surfaces of said metal microtechnology part (10, 10') have been corrected with the method according to one of the claims 15 to 20.