Method and equipment for corrective machining of microtechnology workpieces

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

[0001] PROCESS AND EQUIPMENT FOR CORRECTIVE MACHINING OF MICROTECHNICAL PARTS

[0002] Field of invention

[0003] The invention relates to the general field of microtechnology and in particular to the corrective machining of parts by forceless 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 forceless machining means, such as a very short pulse laser.

[0004] Machining equipment finds particular application in the watchmaking industry, particularly for the production of watch parts. Applications can also be found in the fields of fluidics (nozzles) and medical (bearings, insulators) and connectors (test tips).

[0005] State of the art

[0006] The use of small parts made of metals is known in various fields such as medical applications or watchmaking.

[0007] Traditional machining techniques are mostly limited to machining or shaping techniques using abrasives or chemical or plasma treatment techniques.

[0008] Another technique consists of producing microtechnical parts using a LIGA (Lithography Galvanoforming Abforming) process. Initially, the technique was intended to work with X-rays. The need to implement expensive equipment (synchrotron) makes this technique not very compatible with mass production of microstructures that must have a low unit cost. This is why, based on 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 fabrication of metallic structures by electrodeposition of metal in molds made of photosensitive polyimide-based resin.

[0009] LIGA technology allows the creation of geometries that would otherwise be impossible using standard production processes. LIGA technology is an additive technique that has the advantage of being very inexpensive and can be implemented quickly, making this process very competitive compared to traditional material removal methods. The process is ideal for rapid prototyping as well as for large-scale production and allows for good micrometric precision and good surface finish quality.

[0010] The UV-LIGA process requires tools, industrial equipment and techniques that are very different from conventional micro-fabrication methods.

[0011] A typical process of the LIGA technique consists of:

[0012] - deposit on a substrate a layer of 1 to 1000 pm of a photosensitive resin called photoresist;

[0013] - if necessary, carry out planarization of the photoresist layer by mechanical machining;

[0014] - carry out irradiation through a mask by means of a synchrotron or by exposure to ultraviolet rays;

[0015] - developing, that is to say removing by chemical means, the unpolymerized portions of photoresist and thereby creating a cavity or mold in photoresist;

[0016] - carry out selective gilding on the upper surfaces of the photoresist cavity in the case of the creation of a multi-level cavity;

[0017] - repeat the previous steps to create multi-level cavities;

[0018] - electroform a metal in this cavity in order to obtain the micromechanical component.

[0019] It is also possible to produce microparts that comprise more than a single element. For example, document EP 1 916567 describes a mixed manufacturing process for parts by photolithography, insert additions 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 comprises the following steps:

[0020] - irradiation through a mask of a layer of photosensitive resin applied to a substrate;

[0021] - development of the photosensitive resin layer to form a polymerized resin mold;

[0022] - 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 encloses all or part of the added element;

[0023] - obtaining the part by separating the substrate from the electroformed metal layer attached to the added element and eliminating the photoresist mold.

[0024] The microstructures obtained according to the methods of the prior art have limited precision, which results from the nature of the LIGA process.

[0025] The microstructures obtained according to the methods of the prior art are metallic microstructures made of 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 into a part made of a second metal.

[0026] 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.

[0027] The process, based on photolithography and electroforming, allows for shapes and precision unmatched by traditional methods. Despite this excellent precision, the demand for even better performance continues to increase.

[0028] With the LIGA process, dimensional control (diameter and verticality, for example for a hole) depends on many parameters. 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 deposited metal, for example, are important parameters.

[0029] Repeatability is extremely complicated to master because of all these factors.

[0030] It is therefore obvious that to obtain a hole accurately and repeatably, for example, in a microstructure manufactured by LIGA, a rigorous control of the parameters mentioned above must be carried out. This is not technically and economically imaginable for all parameters. Each hole diameter and each thickness will require specific adjustments of these parameters. If a microstructure has several holes with different diameters and / or thicknesses, it is easy to understand that the precision obtained is the result of a series of compromises.

[0031] In the field of microstructures manufactured by UV photolithography and electroforming, there is no solution that allows achieving accuracies lower than + / -2 pm, or even + / - 1 pm in the best case, in a reproducible manner over 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 flanks, 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.

[0032] There is therefore a need for a new technique that allows improving the precision of micromechanical components produced using the LIGA technique without substantially increasing the cost of their production.

[0033] Subject of the invention

[0034] 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. In order to guarantee even higher accuracies and tolerances, targeted re-machining by force-free machining means, for example by a pulsed laser, is proposed. The retouching of critical dimensions is carried out on identified and rough-cut elements.

[0035] More specifically, the equipment and method of the invention make it possible to correct extremely quickly and reliably by forceless 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 and this at high speed and without substantially increasing their manufacturing cost.

[0036] The equipment and method of the invention make it possible to use force-free machining machines, preferably laser-based, for example a femtosecond laser, which are extremely expensive machines, at their maximum capacity. This is key in the field of manufacturing watch parts but also precision medical parts such as those used for example in endoscopes. A particular application is the production of curved surfaces and holes and openings in LIGA parts and this with very high precision.

[0037] In a first aspect, the invention is obtained by equipment for corrective machining of microtechnology metal parts previously produced by a LIGA process, comprising a machining machine comprising a system for loading / unloading supports for metal parts, force-free machining means for machining said metal parts and a system for controlling said force-free machining means, said machining machine defining a horizontal plane XY and a vertical axis Z orthogonal to the horizontal plane XY.

[0038] Each support comprises, at least on one face, a surface arranged to fix there a plurality of metal parts previously produced by the LIGA process.

[0039] The corrective machining equipment includes at least one corrective machining reference mark XYZ linked to a manufacturing reference mark X1Y1Z1 used when producing metal parts using the LIGA process.

[0040] The corrective machining equipment comprises a system for recording in said manufacturing reference frame X1 Y1Z1 at least one target geometry and at least one predetermined reference position x1, y1, z1 specific to each metal part positioned on the support, said system for recording said target geometries and said positions x1, y1, z1 being arranged to cooperate with the control system of said force-free machining means.

[0041] 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 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 control system of the force-free machining means.

[0042] Said system for controlling said forceless machining means comprises a system for positioning said forceless machining means arranged to, before the corrective machining of each metal part, move and position said forceless machining means in the corrective machining reference frame relative to said metal part 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.

[0043] In one embodiment, said forceless machining means comprises an emitter arranged to emit an electromagnetic wave. In one embodiment, the emitter is configured to emit an electromagnetic wave having a wavelength between 150nm and 1mm, preferably between 200nm and 15pm, even more preferably between 300nm and 5pm.

[0044] Advantageously, the transmitter is a laser.

[0045] 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.

[0046] In one embodiment, at least one corrective machining positioning mark is provided on the metal part support and recognized by the vision system in the corrective machining reference mark, said corrective machining positioning mark 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.

[0047] 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 corrective machining positioning mark 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.

[0048] In one embodiment, the vision system is arranged to perform a 3D geometry and positioning measurement with an accuracy of 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.

[0049] In one embodiment, said support is arranged to carry at least two assemblies containing metal parts of different types.

[0050] In one embodiment, the machining machine comprises a system for releasing, after their corrective machining, at least a portion of the metal parts from their support.

[0051] 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 emitted electromagnetic wave in the 3 dimensions XYZ.

[0052] 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 10000 seconds.

[0053] In a second aspect, the invention is carried out by a method of corrective machining of microtechnology metal parts previously produced by a LIGA method, said method comprising the different steps (AF) consisting of:

[0054] A: provide, on a parts support, metal parts previously produced using a LIGA process;

[0055] B: provide the corrective machining equipment as described and insert at least one of said workpiece holder into said machining machine;

[0056] C: recording in a manufacturing reference frame used during the production of the 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;

[0057] D: recognize, in at least one corrective machining reference frame linked to said manufacturing reference frame, the 3D geometry and the positioning of the metal parts, previously produced by 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 and said calculation unit;

[0058] E: performing 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 with respect to said metal part to be corrected, in order to carry out the corrective machining according to said correction of the geometry determined in step D to obtain said target geometry;

[0059] F: release at least one of said metal parts from its support.

[0060] 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 one manufacturing positioning mark from which the reference position x1, y1, z1 of each part in the manufacturing reference mark 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 have been produced by the LIGA process.

[0061] In one embodiment, said corrective machining positioning reference 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 corrective machining positioning reference mark being linked to at least one manufacturing positioning reference mark from which the reference position x1, y1, z1 of each part in the manufacturing reference mark is defined.

[0062] In one embodiment, said part support is a transfer film made at least partially from a polymer.

[0063] The invention is also obtained by a metallic microtechnology part, obtained by the method as described, and having at least one portion which has, between the dimensions of the corrected part and the target geometry, a difference of less than 2 pm, preferably less than 1.5 pm.

[0064] In one embodiment, the metal microtechnology part, as described, comprises at least two surfaces of said metal microtechnology part which have been corrected with the described method.

[0065] Descriptions of the figures

[0066] The invention will be better understood by reading the detailed description of an exemplary embodiment made with reference to the appended figures, among which:

[0067] - Figure 1 represents steps of a LIGA process and of a transfer process onto a part support according to the invention;

[0068] - Figure 2 represents a part support comprising metal parts produced by a LIGA process, according to the steps illustrated in Figure 1;

[0069] - Figure 3 shows a schematic diagram of a force-free machining machine;

[0070] - Figure 4 represents the diagram of a part correction equipment comprising a force-free machining machine preferably comprising a femtosecond laser, a vision system and a computing unit;

[0071] - Figure 5 represents a vertical section of a part produced by a LIGA process; - Figure 6 represents a laser beam directed onto a microtechnical part according to Figure 5 in order to carry out a shape correction by ablation of material using a force-free machining system;

[0072] - Figure 7 represents a laser beam directed onto a microtechnical part, in a position to produce a target diameter of an opening;

[0073] - 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;

[0074] - Figure 9 represents a multi-level micro-part, comprising holes, produced with the part correction equipment and the method according to the invention;

[0075] - Figures 10-12 illustrate metal parts made by the part correction equipment and the method according to the invention;

[0076] - Figure 13 shows a part manufacturing base comprising metal parts made by a LIGA process. Figure 13 also illustrates manufacturing positioning marks on the part manufacturing base;

[0077] - 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, comprising the parts made during the LIGA process;

[0078] - Figure 15 illustrates a corrective machining reference frame of the machining machine based on three corrective machining positioning reference structures that have been transferred from the manufacturing base to a workpiece support.

[0079] - Figure 16 illustrates the coordinates of 4 particular points of an asymmetric object relative to a manufacturing reference frame X1-Y1 -Z1 linked to the LIGA process;

[0080] - Figure 17 illustrates the coordinates of 4 particular points of an asymmetrical object brought onto a part support relative to a corrective machining reference frame XYZ of the machining machine;

[0081] - Figure 18 illustrates a wafer 1 comprising workpieces to be machined and manufacturing positioning marks, the wafer 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 are merged with the manufacturing positioning marks 20, 22, 24 of the wafer 1; - Figure 19 illustrates a workpiece support 2 comprising workpieces to be corrected and which have been transferred from a manufacturing base 1 onto said workpiece support 2. The workpiece 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 frame XYZ of the machining machine 200 and which is based on the corrective machining positioning marks 30, 32, 34 of the workpiece support 2 in connection with manufacturing positioning marks of a manufacturing base. Figure 20 illustrates a portion of a workpiece support comprising position marks in proximity to the metal parts on the workpiece support;.

[0082] - Figure 21 shows a substrate comprising metal parts made by a LIGA process;

[0083] - Figure 22 shows a flexible part support comprising metal parts made by a LIGA process.

[0084] Description of embodiments of the invention

[0085] The invention relates to a method for the corrective machining of small metal parts previously produced using a LIGA process. The method makes it possible to produce very high-precision metal parts, i.e. having surfaces, dimensions and shapes that are defined with accuracies of less than 2 pm, or even less than 1 pm.

[0086] Although a preferred application of the invention relates to 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 machined surfaces such as curved surfaces or surfaces defined by a polygon in at least one section of said metal part.

[0087] For example, the dimensions of metal parts used in watch mechanisms are very small and it is very difficult to machine them accurately and at low cost and 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.

[0088] It is well known that it is very difficult to load and unload individual microtechnology parts very quickly into a machining center to ensure the machining rate. Standard methods use vibratory bowl feeders or vision-guided flexible feed systems that directly load microtechnology parts into clamping 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. In addition, they are unable to achieve very high loading / unloading rates (rates between 0.5 seconds and 1 second per part).

[0089] Producing metal parts with the desired geometry achieved with very high precision, typically in the order of a micrometer, using methods based on machining by applying force requires machining part by part, which is very expensive and does not always allow the required precision to be obtained.

[0090] The equipment and method of the invention propose a method based on carrying out a correction, without applying force, of the dimensions and / or shapes of parts produced by LIGA process. It is understood here that the term "without force" means machining without direct contact between a machining tool and the parts to be machined, for example by the use of lasers.

[0091] The correction process can be carried out directly on a manufacturing base also defined as a wafer, on which parts 10, 10' were produced using the LIGA process. This is illustrated in Figure 18.

[0092] In another embodiment, the correction process is carried out on parts produced by LIGA which have been transferred onto a part support 2. As described later, the transfer can be carried out by a polymer film or by another transfer technique.

[0093] 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 produced by LIGA process. The term "machining" also includes a simple 3D shape correction of the parts without necessarily removing material from the parts.

[0094] In this description, "forceless machining" is an unconventional machining in which there is no mechanical action transmitted by direct contact and force between a tool and the workpiece, unlike conventional machining where there is direct contact between the tool and the workpiece and in which significant cutting forces are involved. Forceless machining is therefore machining without direct contact between the workpiece and a machining tool which would be likely to exert a force or stress on said workpiece. Forceless machining is machining with a machining force of less than one Newton (N) or a specific cutting pressure of less than one N / mm2.

[0095] Corrective machining equipment is defined as a machining system that allows the correction of a pre-defined shape. For example, the system can be designed to correct the size of an opening or a part diameter. Corrective machining equipment does not create a shape from a block of material of any shape, such as a cubic shape to create a cylinder, but only corrects a shape previously created using the LIGA process. In the case of a cylinder with a hole, the machining system will only be designed to correct the diameter of the hole and / or the outside diameter of the cylindrical part. There are two cases for corrective machining:

[0096] I) in the first case the corrective machining machine performs the correction directly on parts on the manufacturing base which has been introduced into the machine.

[0097] 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, onto a part support introduced into the corrective machining machine.

[0098] Definitions of the manufacturing and corrective machining reference frames XYZ, X1-Y1-Z1 and the manufacturing and corrective machining positioning frames':

[0099] - The manufacturing reference frame 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.

[0100] - 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 corrective machining reference frame XYZ.

[0101] It is understood that the corrective machining and manufacturing reference marks XYZ, respectively X1 -Y1 -Z1, are centered on a virtual reference center RC provided on the machining machine, RC' provided with respect to the LIGA process. For example, the axes X, Y, and X1, Y1 may each be parallel to two positioning marks 30, 32, 34, respectively 20, 22, 24, or are parallel to the two axes of a 2D shape mark, for example a cross shape. Corrective machining and manufacturing reference marks XYZ, X1Y1Z1 are illustrated in Figures 14-19.

[0102] - 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 mark can be a point structure or a structure which has a 2D shape such as a cross. If the marks are point structures, at least 3 marks 20-24 are required. The relative position of the parts to be corrected with respect to said manufacturing reference marks 20-24 is known precisely by the masks used during the LIGA process. The relative accuracy 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.

[0103] - 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 onto the support and which is read by the machining machine to define its position in the corrective machining reference mark, which makes it possible to determine, in the corrective machining reference mark of the machining machine 200, an x, y, z position. The identification of the corrective machining positioning marks in the corrective machining reference mark makes it possible to determine, for example, whether the transfer film has been deformed, which could result in the relative positions of the corrective machining positioning marks 30-34, 40-47 being different from the relative positions of the manufacturing positioning marks 20, 22, 24 in the manufacturing reference mark.

[0104] If the correction of the parts to be carried out is carried out directly on the manufacturing plate 1, the corrective machining reference mark and the manufacturing reference mark can be merged and are based on the relative positions of the manufacturing positioning marks 20-24 which are merged with the corrective machining positioning marks. The corrective machining positioning marks can advantageously be used to define the corrective machining reference mark XYZ.

[0105] The equipment and method of the invention make it possible to carry out a correction of the dimensions and / or the desired shape by said forceless machining, also defined as "forceless correction". The metal parts are produced in batches using a LIGA technique and with an average precision, typically of + / - 2 microns, characteristic of the LIGA process, and are finalized by final machining without applying force.

[0106] It is understood that all embodiments and variants of the equipment of the invention may be combined with each other in any technically compatible combination. It is also understood that all embodiments and variants of the method of the invention may be combined with each other in any technically compatible combination.

[0107] The equipment and method of the invention may comprise at least one of the following forceless machining means:

[0108] - machining by emission of an electromagnetic wave, for example a beam of light such as a laser beam;

[0109] - plasma machining, preferably directional plasma;

[0110] - machining by microwaves, preferably directional microwaves;

[0111] - electrochemical machining, preferably local electrochemical etching (ECM). The ECM process is a machining method generally used for deburring, hollowing, polishing or drilling. Electrochemical machining requires two basic components: the electrolyte and the electric current. The "electrolyte" is, for example, salt water which constitutes the conductor of the electric current;

[0112] - machining by magnetic effect;

[0113] - machining by electron, proton or neutron beam;

[0114] - machining using an electric arc, for example by die-sinking electroerosion, also commonly called EDM (English term meaning “electrical discharge machining”);

[0115] - wire machining and electroerosion.

[0116] The various methods of forceless machining do not necessarily have to remove material. For example, by induction a portion of a part can be deformed, such as a small correction of the radius of curvature of a thin membrane.

[0117] It is understood that at least two machining means can be implemented, whether in operation at the same time or according to deferred machining times. For example, the metal parts can first undergo radiation from an infrared flux in order to soften or deform a metal part 10, 10', followed by local machining by femto laser.

[0118] Description of the Equipment

[0119] More specifically, in a first aspect, the invention relates to equipment for corrective machining of microtechnology metal parts 10, 10' previously produced 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', force-free machining means for machining 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.

[0120] Each part support 2 comprises, at least on one face, a surface 2a, 2b arranged to fix there a plurality of metal parts 10, 10' previously produced by the LIGA process.

[0121] 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 the corrective machining positioning marks 30-34 on the workpiece supports 2 introduced into the machining machine.

[0122] This is illustrated in Figures 14 and 15.

[0123] 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 wafer 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 .

[0124] In the case of a transfer of parts onto a part support 2 illustrated in Figure 15, the three manufacturing positioning marks 20, 22, 24 are transferred identically onto a part support 2 to form three corrective machining positioning marks 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 therefrom the position and orientation of the metal parts 10, 10' in said corrective machining reference mark XYZ.

[0125] Thus, the position and orientation of the metal parts 10,10' are perfectly known in relation to the corrective machining reference frame XYZ and can be used for the correction operation.

[0126] 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 maximum 2D dimension of the part, and two other points C, D define the minimum dimension of the part.

[0127] In case 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 be caused, for example, by the contraction or elongation or twisting of the transfer film during transfer.

[0128] 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 that are perpendicular. Fig. 19 illustrates a part support where the X1 and Y1 axes form an angle [3 which is different from 90°.

[0129] The relative position of the initial marks 20-24 can then be altered, for example by a 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.

[0130] 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 manufacturing positioning marks.

[0131] Thus, in all embodiments, the position and orientation of the metal parts 10, 10' are perfectly known relative to the corrective machining reference frame XYZ and can be used for the correction operation.

[0132] In order to achieve 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.

[0133] More specifically, 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' relative to a manufacturing reference frame X1Y1Z1, said system for recording said target geometries and said positions x1, y1, z1 being arranged to cooperate with the control system of said force-free machining means, the target position of the parts always being defined in the manufacturing reference frame.

[0134] The corrective machining equipment comprises a vision system 120 and a calculation unit 130 for recognizing, in the corrective machining reference frame XYZ, the 3D geometry and the positioning of the metal parts 10, 10' previously produced by LIGA process and for determining a correction of the geometry to be made with respect 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 control system of the force-free machining means. Advantageously, a lighting system 140 for the parts 10, 10' or a portion of the part support 2 is adapted in the machining equipment, preferably adapted to the vision system 120 as illustrated in Figure 4. The lighting system can emit a UV, visible or infrared beam 142 which can be divergent, collimated or focused.

[0135] Said system for controlling said forceless machining means comprises a system for positioning said forceless machining means arranged to, before the corrective machining of each metal part 10, 10', move and position said forceless machining means in the corrective machining reference frame relative 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 forceless machining means in an XYZ space is illustrated by the symbols AX, AY, AZ.

[0136] In a preferred embodiment, illustrated in Figure 3, the forceless machining means comprise an emitter 100 arranged to emit an electromagnetic wave 110. In other embodiments, the emitter 100 is an emitter of particles such as electrons, protons or neutrons. In other embodiments, the emitter comprises a generator of an electric and / or magnetic field, for example an induction coil. In other embodiments, the emitter 100 is a part adapted to emit an electric arc. Of course, an emitter can comprise at least two emitters of different types.

[0137] Preferably, the emitter 100 is configured to emit an electromagnetic wave 110 having a wavelength between 150nm and 1mm, preferably between 200nm and 15pm, even more preferably between 300nm and 5pm. In one embodiment, the emitter 100 is a laser, preferably pulsed, configured to emit a laser beam 110. The latest generation lasers with ultra-short pulses allow controlled and precise removal of material. The proposed solution combines corrective machining by ultra-short wave laser on components previously manufactured by LIGA technology.

[0138] Advantageously, said laser 100 may be a femtosecond laser, configured to emit pulses having a duration of less than 900 femtoseconds, preferably less than 400 femtoseconds. The machining of a surface and / or internal hole of a metal part by laser, preferably a femtosecond laser, is very fast, and the machining can be done in approximately 0.5 to 1.5 seconds depending on the dimensions of the openings to be made. Typical opening diameters are between 0.05 mm and 2 mm.

[0139] Typical pulse durations for a 100 pulsed laser are preferably between 1000 fs and 40 fs.

[0140] 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.

[0141] Advantageously, the emitter 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 1030 nm, a typical roughness is 100 nm or better.

[0142] In embodiments the maximum energy per laser pulse is advantageously close to 2 mJ.

[0143] The laser power is typically 20 W, but must be adapted according to the material of the metal parts 10, 10'.

[0144] One of the advantages of manufacturing microstructures by photolithography and electroforming is that it is possible to manufacture a large number of parts on the same basic substrate.

[0145] The retouching can therefore be done when the metal parts 10, 10' are still all positioned on the part support 2 in the same configuration as they had on the substrate 1 during the LIGA process. Since the parts are positioned on said part support 2 in a manner identical to the configuration of the substrate 1, there is no need for a system for feeding and orienting the metal parts 10, 10'. A system for moving 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'.

[0146] Another advantage of this manufacturing method is that the positioning of each part 10, 10' on the part support 2 is perfectly known. This is not essential for the corrective machining equipment and the 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 part support 2 is a flexible support. The transfer of the parts from the substrate 1 on which the 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 method of the invention.

[0147] It is therefore preferable to use this positioning to perfectly center the retouching by the emitter 100 after an optical measurement of the location of the hole, for example. The retouching by micro-machining by the emitter 100 is then facilitated, because the positions of the metal parts 10, 10' are perfectly known. In order to avoid long machining times, the 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 roughed out by LIGA technology. Laser re-machining will only be used to complete the dimensions of the hole to the last microns and obtain the required verticality and precision.

[0148] 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 of which the average diameter D0 does not have the correct 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).

[0149] In one embodiment, illustrated in Figure 4, the corrective machining equipment comprises a loading / unloading system 300 for workpiece supports 2.

[0150] Positioning markers

[0151] In one embodiment, at least one corrective machining positioning mark is provided on said support 2 of metal parts 10, 10'.

[0152] 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 to 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.

[0153] Figure 13 illustrates a wafer-shaped substrate 1 comprising a plurality of manufacturing positioning marks 20, 22, 24, 26.

[0154] Figure 20 illustrates corrective machining positioning marks 40, 41, 42, 43, 44, 45, 46, 47 which originate from a transfer of corresponding manufacturing positioning marks provided on the plate 1. Advantageously, these corrective machining positioning marks 40, 41, 42, 43, 44, 45, 46, 47 are located in proximity to the parts 10, 10', 10”, 10'” which are to be corrected.

[0155] The corrective machining positioning mark does not necessarily have to be located on said workpiece support 2. Indeed, in another embodiment the corrective machining positioning mark is provided on the machining machine 200.

[0156] 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.

[0157] In one 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 one variant, each metal part 10, 10', 10”, 10'” has its own corrective machining positioning mark near it.

[0158] In a variant, the corrective machining positioning reference frame is an element of the metal part 10, 10'. As above, it is recognized by the vision system in the corrective machining reference frame XYZ. 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 frame X1Y1Z1.

[0159] In the case of asymmetrically shaped parts, the orientation must also be known. In some 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 parts 10, 10' in the manufacturing reference frame X1Y1Z1 without the need for a record of the entire circumference of the part. In the case of transfer to a part holder 2 in the corrective machining reference frame XYZ, as illustrated in Figure 17, knowledge of the coordinates x, y, z of the transferred characteristic points A', B', C', D' helps to ensure a fast machining speed.

[0160] Of course, the equipment and the method of the invention can implement different corrective machining positioning marks, for example at least one mark on the part support and at least one mark on a frame which holds the part support.

[0161] Vision system(s)

[0162] In one embodiment, the vision system 120 is arranged to carry out a 3D geometry and positioning measurement with an accuracy of 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.

[0163] Preferably the 120 vision system comprises:

[0164] - a CCD sensor

[0165] - a telecentric optic

[0166] - telecentric lighting

[0167] - at least one means of calibration

[0168] The vision system 120 preferably also comprises suitable image processing means. For example, the vision and recognition system may comprise image processing means which take into account the diffraction effects encountered during the optical resolution of features and small dimensions.

[0169] A vision system, including means of compensating for diffraction effects, makes it possible to achieve measurement and repeatability accuracies of ±0.2 um.

[0170] 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 may be adapted during the operation of correcting the metal parts 10, 10'.

[0171] 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 an optical vision system 120 which is preferably fixed 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 may advantageously comprise a system for determining the vertical position z of the metal parts 10, 10'. Advantageously, such a vertical position measuring system 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 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 ensure 2D images for a certain vertical position. For example, the vision system can be moved in a 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 accuracy of the 3D xyz measurement of the metal parts 10, 10'.

[0172] Advantageously, the xyz position measuring device is arranged to perform a measurement with an accuracy of less than 20 pm, preferably 10 pm, more preferably 5 pm, and preferably less than 2 pm, in the 3 axes X, Y, Z.

[0173] Other embodiments

[0174] 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 emitted machining beam 110 in the 3 dimensions X, Y, Z. In an alternative embodiment, the transmitter 100 is a laser and the orientation system comprises an optical system in order to be able to orient the emitted beam 110 in space.

[0175] In variants of the invention, said system for controlling the force-free machining means may be arranged to machine at least a portion of the metal parts 10, 10' according to different machining steps. For example, a portion of the parts 10, 10' fixed on said part support 2 would require having a height, defined in the Z axis, reduced by 3 pm and another portion of the parts 10, 10' would require a height correction of only 1 pm.

[0176] Advantageously, a part holder 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.

[0177] In one embodiment, not illustrated in the Figures, the machining machine 200 comprises a system for releasing, after their machining, at least a portion of the metal parts 10, 10' from their support 2.

[0178] 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 may make it possible to machine two sets of metal parts 10, 10' by two different lasers of the machining machine 200 or may make it possible to machine two sets of parts by two different operating modes of an emitter such as a pulsed laser. These different operating modes may consist of the use of different energies or powers, and / or by an adjustment of the numerical aperture of the laser beam.

[0179] In an alternative embodiment, the machining machine 200 comprises a machining program for machining at least a portion of the metal parts 10, 10' according to different machining steps. For example, each part may be processed to produce a hole, followed by an operation for processing an edge or a circumference of the metal part 10, 10'.

[0180] In one embodiment, the inventive machining machine 200 may include at least two lasers that produce non-parallel beams. For example, a first femtosecond laser may be adapted to make apertures and another laser may be used to produce a beam that is not parallel to the beam of the first laser.

[0181] Advantageously, the machining machine 200 of the invention can comprise at least one multi-beam optic, suitable for carrying out simultaneous machining of several parts at the same time.

[0182] Process

[0183] The invention also relates to a method for corrective machining of microtechnology metal parts previously produced by a LIGA method, said method comprising the different steps (AF) consisting of:

[0184] A: providing on a part support 2 metal parts 10, 10' previously produced by a LIGA process; B: providing the corrective machining equipment, as described, and inserting at least one of said part support 2 into said machining machine 200;

[0185] C: recording, in a manufacturing reference frame X1Y1Z1 used during the production of the metal parts 10, 10' by the LIGA process, a target geometry and at least one predetermined reference position x1, y1, z1 specific to each metal part 10, 10' positioned on said part support 2;

[0186] D: recognize, in at least one corrective machining reference frame XYZ, in connection with the manufacturing reference frame 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;

[0187] E: performing corrective machining steps of said metal parts 10, 10' by said forceless machining means which are, before the corrective machining of each metal part 10, 10', moved and positioned in the corrective machining reference frame XYZ relative to said metal part 10, 10' to be corrected, and to carry out the corrective machining according to said correction of the geometry determined in step D, so as to obtain said target geometry;

[0188] F: release at least one of said metal parts 10, 10' from its support 2.

[0189] In another embodiment, during said step A, the part 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 merged, and the corrective machining and manufacturing positioning marks are also merged.

[0190] In an advantageous embodiment, the positioning mark of the corrective machining provided on said support 2 has been transferred from the substrate 1 in which the metal parts 10, 10' have been produced by the LIGA process from a manufacturing positioning mark.

[0191] 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 corrective machining positioning mark 30, 32, 34, 40-47 being linked to at least one manufacturing positioning mark 20, 22, 24, 26 from which the reference position x1, y1, z1 of each part is defined in the manufacturing reference mark X1Y1Z1.

[0192] 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' have been produced by the LIGA process.

[0193] Once the metal parts 10, 10' have been loaded and referenced on the XY-Z table of the machining machine 200, the corrective machining rate of the metal parts 10, 10' arranged on a part 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 taken to move the table from one metal part 10, 10' to the next. The corrective machining time is typically 0.3 to 1 second depending on the size and the gap between each metal part 10, 10'. For parts 10, 10' with an outside diameter of 0.9 mm, more than 8,000 metal parts 10, 10' can be arranged on a round support with a diameter of 150 mm. Loading and unloading the 2-part carriers is extremely easy, and even if it is not fast, the time is divided by the number of 10 parts, 10' per 2-part carrier.An automatic part support loading system 2 allows the machining machine to operate completely autonomously for very long periods, despite a corrective part machining cycle time that is typically around 1 second.

[0194] In a typical example, the vision system 120 proceeds by taking pictures of each of the metal parts 10, 10' individually. In an advantageous example, in order to reconstruct the xyz position of all the metal parts 10, 10', the vision system 120 proceeds by taking successive pictures of 10 to 15 metal parts. In a variant of the method, during step E, the positioning of the forceless machining means 100, relative to said metal parts 10, 10', is done by a movement in an XY plane or in the X--Z space of said forceless machining means 100.

[0195] 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.

[0196] It is also possible that, during step E, the positioning of the force-free machining means is done by a movement of said transmitter 100 and also of 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.

[0197] In one 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'.

[0198] In one embodiment, 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'.

[0199] The part supports 2 can be of any shape, typically rectangular, square or circular. Preferably, the support is a flexible film made of a polymer. In this case the film is held in a frame as a 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 allow sawing, machining or thinning of wafers, for example.

[0200] The coin holder 2 may be a transparent glass holder, for example made of borosilicate glass. The coin holder 2 may be a wafer, commonly called a wafer in English, made of a semiconductor material, a metal alloy, a ceramic material or other material.

[0201] In one embodiment, the coin holder 2 may be a combination of the holders described above.

[0202] If the part support 2 is a polymer film, the machining of the parts 10, 10' may be accompanied by drilling of the support 2. For example, when widening a hole, a laser may pierce the part support 2 and thus more easily remove the metal removed from the parts 10, 10'.

[0203] If the part support 2 is made of a hard material and includes an adhesive film, the part supports 2 can be drilled. By using part supports 2 that 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 method described), the fact of having an opening under each metal part makes it easy to pass through the adhesive film of the part support 2 that will be drilled, forming an opening in the adhesive film. 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 that is located under the metal part 10, 10'. This evacuation can be done by suction or by a pressurization system.The adhesive film also ensures that the metal parts cannot move or vibrate during laser machining. A simple part placement could not be used when transferring parts to a part holder.

[0204] In variants, said adhesion film may be a semi-adherent or adhesive layer such as a double-sided adhesive tape, for example a polymer film, which is fixed to a part support 2. Certain types of adhesive films used in microtechnology make it possible to ensure adhesion strength without having to use glues. These films are commonly called “blue tapes” and are known to those skilled in the art of microtechnology.

[0205] Advantageously, the adhesion of a transfer film is typically between 0.50 and 4.50 N / 25mm

[0206] In embodiments the transmission, for wavelengths between 400nm and 3pm is at least 25%, preferably at least 50% and more preferably at least 75%.

[0207] In embodiments the thickness of said transfer film is between 0.80 and 1.25 mm.

[0208] 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.

[0209] In one embodiment, machining can also be done by directing the laser from the opposite side of the parts that are arranged on the part support 2.

[0210] In one embodiment, openings may be provided in the adhesive film under each part.

[0211] Advantageously, in one variant, a force-free machining system using a laser 100 may comprise an optic delivering more than one laser beam, typically 2, 4, 9, 16 or more beams. This allows the simultaneous machining of several metal parts 10, 10' at the same time.

[0212] It is understood that the multibeams are Gaussian in 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 that is directed onto the workpiece. Reference is made here to the following publication: https: / / www.pulsar-photonics.de / en / optical-modules / multibeamscanner-mbs /

[0213] With a suitable optical element, it is possible to carry out almost any correction of parts 10, 10' ensuring high homogeneity and high overall efficiency. By combining a multi-beam system with at least one galvanometric scanner, it is possible to generate a large number of treatment points in the treatment plane, which are moved simultaneously on the metal part 10, 10' by said scanner.

[0214] Pulsar Photonics, for example, whose reference can be found at https: / / www.pulsar-photonics.de / , offers a multi-beam scanner solution for laser multi-beam processing. Such a system comprises at least one beam scanner based on a galvano system. A selectable beam splitter with a multi-beam module generates a fixed beam arrangement in the working plane of the scanning system. This approach allows for a multi-fold increase in process speed in the production of periodic structures.

[0215] Using a diffractive beam splitter, the power of the laser system can be divided into up to 100 or more partial beams. Typical beam distributions can be, without limitation: 2x2, 4x4, 8x8, where nxm or n and m are different numbers. It is understood that the laser beams can be different, for example they can have a different focal length.

[0216] The use of a multi-beam system allows efficient parallel production of identical structures in a single step.

[0217] It is thus possible to overcome the power limitations, essentially of physical origin, of many "ultra short pulse" processes and thus considerably increase the efficiency of the processes.

[0218] Areas of application are drilling, parallel processing of several components or general parallelization of processes.

[0219] The release of the metal parts 10, 10', attached to the part 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 the bonding interfaces. The release can also be done by exposure to heat or flashes of infrared radiation. Said UV and / or infrared radiation can be carried out by pulsed power sources.

[0220] In variants, the part release step F can be done in various ways:

[0221] - by application of vibration and / or shocks;

[0222] - by mechanical scraping;

[0223] - by using a “pick and place” arm or robot;

[0224] - by liquid and / or ultrasonic means;

[0225] - by blowing with air or other gas. Transfer technique on the part support 2 after LIGA process

[0226] The technique of transferring parts 10,10' produced by the LIGA process onto a part support 2 is now described in detail and reference is made to Figure 1.

[0227] The advantage of the LIGA technique is that it produces metal 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 multi-level microcomponent, each level being built on the previous one.

[0228] The positioning of the metal parts 10, 10' relative to each other and to reference marks is known, because the parts remain in the same position as their original position on the wafer throughout the process.

[0229] The wafer 1, also defined as a substrate, is generally a support plate of glass, metal or silicon on which is deposited a conductive layer made by evaporation of chromium and gold, for example. 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 ultraviolet rays UV called hereinafter "photoresist", typically of the SU-8 family from MicroChem Corporation. It is also possible to use dry photosensitive resin, that is to say without solvent or with very low solvent levels. Alternatively, the photoresist could be of the positive type.

[0230] 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.

[0231] Once developed, that is to say after removal of the non-polymerized parts of photoresist, a mold 3 is obtained in photoresist. This mold 3 is illustrated in figure 1, step 1 a and the parts of photoresist removed reveal cavities. On a single-level mold, these cavities reveal the conductive substrate 1.

[0232] 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 metallic 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. In the figure of step 1 b, a slight overflow of the metallic part 5 can be seen. It is customary, but not necessary, to extend the electroforming once the upper level of the mold 3 is reached to ensure that all the cavities are filled. Figure 1 b illustrates the state in which the assembly is at the end of these operations. The electroformed metallic layer forms a plurality of metallic portions 5 linked together by the photoresist mold 3 and secured to the conductive substrate 1.

[0233] In this description, the "external face" is the face of the metal parts corresponding to the free side of the electroforming metallization. The "internal face" is the one which, during metallization, is in contact with the conductive substrate 1. The electroforming metallization creates metal portions 5 with a raw external face 5a and a raw internal face 5b. They are called "raw" because they are directly resulting from the electroforming, either unmachined or polished.

[0234] 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 1c allowing the machined external face 5c of the metal portions 5 to be seen.

[0235] The next step is to remove the photosensitive resin mold 3 by chemical etching. The conductive substrate 1 will remain, secured to the plurality of metal portions, as illustrated in step 1 d.

[0236] 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 removal of the mold 3, that is to say, be in contact with the conductive substrate 1. This binder resin 4 will also exceed the height of the metal portions as illustrated in step 1 e.

[0237] Next comes the preparation of the assembly by lowering and flattening the binder resin 4 to form a reference surface 4' that is flat and 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. The assembly of the metal portions 5 and the binder resin 4 forms a rigid whole. The result is illustrated in Figure 1g.

[0238] Said binder resin 4 may be, for example, a hot melt glue based on natural shellac and a mineral filler which may be in powder or lump form. The cement product B67 or MelBo325 from Stettler Sapphire (internet ref: https: / / www.stettlersapphire.ch / index.php / fr / ), for example, may be used.

[0239] 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 in step 1 h of figure 1.

[0240] A transfer film, which is the part support 2, is applied to the machined inner 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 forceless machining method 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' are thus in the same position in the XY plane as during the manufacture of the photoresist mold as well as all the other steps in which the substrate 1 was present.

[0241] It is also understood that the force-free machining equipment may be adapted to perform 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, drilled metal parts 10, 10' may be processed inside or outside the machining machine 200 in order to clean them or for a plasma smoothing treatment performed on all the parts 10, 10' on a part support 2. It is also understood that, in one embodiment, the machining machine 200 may comprise means for depositing a coating on the parts 10, 10' before or after their machining.

[0242] In an advantageous embodiment, all of the parts 10, 10' may undergo a first corrective machining step which may be a surface preparation step performed for example by said femtosecond pulse laser. In a variant, all of the metal parts 10, 10' may undergo a cleaning and / or layer deposition step.

[0243] Depositing a layer before corrective machining with the femtosecond laser allows for better delineation of the corrective machining area. This layer can be removed after the corrective machining process.

[0244] It is understood that the corrective machining conditions can be adapted according to the location (i.e. drawer) of a cassette system 300 of the corrective machining equipment of the invention. Thus, a first drawer can comprise a support 2 with parts 10, 10' in which a hole is to be corrected and another drawer can comprise another support with parts whose surface is to be corrected or on which a predetermined shape is to be executed.

[0245] In one embodiment, the workpiece carrier 2 in a drawer of a cassette system 300 may undergo several corrective machining cycles. For example, during a first cycle all the workpieces 10, 10' are processed to correct a hole and during a second loading of workpiece carriers 2 into the machining machine 200, all the workpiece carriers 2 may be passed through the machining machine again in order to correct for example an edge of the workpieces 10, 10'.

[0246] In one embodiment, during at least a second machining cycle, at least one other type of laser may be used. This laser may be another femtosecond laser.

[0247] 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 part support 2. For example, the metal parts 10, 10' may be arranged in a disc-shaped or rectangular arrangement.

[0248] In one embodiment, the parts 10, 10' can be fixed on both sides of a part support 2, for example by temporary gluing. A double-sided arrangement (not shown in the Figures) makes it possible to increase, for example by a factor of 2, the corrective machining speed 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 in order to allow autonomous and more precise production.

[0249] Metal parts made

[0250] There is no limitation on the shape or 3D dimension of the metal parts 10, 10' produced by the equipment and method of the invention.

[0251] 10, 10' metal parts are typically millimeter or micrometer in size. Femtosecond laser machining allows for very high machining accuracies, typically smaller than ±1 pm. Surface roughness in cutting mode can reach roughnesses of 50nm or less.

[0252] In one embodiment, a metallic microtechnology part 10, 10' is obtained by the method described and comprises at least one portion which has, between the dimensions of the corrected part and the target geometry, a difference of less than 2 pm, preferably less than 1.5 pm.

[0253] In another embodiment at least two surfaces of said metal microtechnology part 10, 10' have been corrected with the method according to the invention.

[0254] Figures 9-12 illustrate metal parts made by the part correction equipment and method according to the invention.

[0255] Figure 9 represents a metal part 10 comprising structures made in 3 different planes P1, P2, P3 and comprising openings 10a, 10b, 10c.

[0256] Figure 10 shows a watch anchor produced according to the method of the invention.

[0257] Figure 11 shows a clockwork toothed wheel produced according to the method of the invention.

[0258] Figure 12 shows a connector part produced according to the method of the invention. The part 10 illustrated in Figure 12 may comprise at least one surface 10e, 10d which has been corrected with the method and the machining equipment according to the invention.

[0259] Example of application and configuration of corrective machining equipment for microtechnology metal parts (10, 10') according to the invention.

[0260] The following example shows an application case with 10, 10' metal parts on 2 part supports with a diameter of 150 mm. For 10, 10' parts with a diameter of 0.9 mm, approximately 8,000 parts can be produced on a 2 part support which is preferably an insert and corrective machining rates of approximately 1 second can be achieved, i.e. between 8 and 10 times lower than what could be obtained with a conventional approach.

[0261] In a preferred configuration, the corrective machining equipment comprises:

[0262] - a loading / unloading system for at least 25 part holders 2;

[0263] - a measuring system 120 capable of very precisely measuring the position x, y, z of each metal part 10, 10' in the corrective machining reference frame XYZ;

[0264] - a 200 machining machine comprising a femtosecond laser.

[0265] In the example, 8,000 metal parts 10, 10' can be aligned on a single part 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.

[0266] The various operations can take the following times:

[0267] - laser machining per part: 0.5 to 0.6 sec;

[0268] - repositioning of the XY table: 0.3 sec;

[0269] - loading and unloading by coin holder 2: 120 sec;

[0270] - time for measurements: 60 sec.

[0271] This indicates a corrective machining and measurement time of 10, 10' parts typically below 2 seconds, more precisely 0.92 sec for the example described.

[0272] In the execution example, the cassette system will therefore include a maximum of 25x8000 parts to be machined, therefore a maximum of 200000 parts 10, 10'.

[0273] The method and the machining machine 200 of the example make it possible to insert the workpiece support 2 under a femtosecond laser 100 and to correct all the workpieces 10, 10' on a single workpiece support 2. When all the workpieces 10, 10' fixed on a workpiece support 2 are corrected, it is unloaded to a drawer of a cassette system 300 associated with the machining machine 200 and corrective machining of the metal workpieces fixed on a second workpiece support 2', 2”, 2'” and so on is carried out.

Claims

Demands 1. Corrective machining equipment for microtechnical metal parts (10, 10') previously produced by a LIGA process, comprising a machining center (200) including a loading / unloading system (300) for supports (2) of metal parts (10, 10'), forceless machining means for machining said metal parts (10, 10') and a control system for said forceless machining means, said machining center (200) defining a horizontal plane X-Y and a vertical axis Z orthogonal to the horizontal plane XY, characterized in that - each support (2) includes, at least on one face, a surface arranged to fix a plurality of metal parts (10, 10') previously produced by LIGA process; - the corrective machining equipment includes at least one corrective machining datum (XYZ) linked to a manufacturing datum (X1Y1Z1) used during the production of the metal parts (10, 10') by the LIGA process; - the corrective machining equipment includes a recording system in said manufacturing reference frame (X1Y1 Z1) of at least one target geometry and at least one predetermined reference position (x1 , y1 , z1) specific to each metal part (10, 10') positioned on the support (2), said recording system of said target geometries and said reference positions (x1 , y1 , z1) being arranged to cooperate with the control system of said forceless machining means; - the corrective machining equipment includes a vision system (120) and a calculation unit (130) enabling recognition, in the corrective machining reference frame (XYZ), of the 3D geometry and positioning of the metal parts (10, 10') previously produced by LIGA process and determining a correction of the geometry to be made with respect to the target geometry and said reference position (x1, y1, z1) recorded, at least the calculation unit being arranged to cooperate with the control system of the forceless machining means; - said control system for said non-force machining means includes a positioning system for said non-force machining means arranged to, before corrective machining of each metal part (10, 10'), move and position said non-force machining means in the reference frame corrective machining reference (XYZ) relative to said metal part (10, 10') to be corrected and to perform corrective machining based on said geometry correction, so as to obtain said target geometry. Corrective machining equipment according to claim 1, characterized in that said forceless machining means comprise an emitter (100) arranged to emit an electromagnetic wave. Corrective machining equipment according to claim 2, characterized in that the emitter (100) is configured to emit an electromagnetic wave having a wavelength between 150 nm and 1 mm, preferably between 200 nm and 15 pm, even more preferably between 300 nm and 5 pm. Corrective machining equipment according to claim 3, characterized in that the emitter (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 any 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 frame (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 frame (X1Y1Z1) is defined.Corrective machining equipment according to any one of claims 1 to 5, characterized in that at least one corrective machining positioning datum (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 datum (XYZ), said corrective machining positioning datum being linked to at least one manufacturing positioning datum from which the reference position (x1, y1, z1) of each part in the manufacturing datum (X1Y1Z1) is defined. Corrective machining equipment according to any one of claims 1 to 7, characterized in that the vision system is arranged to perform 3D geometry and positioning measurements with an accuracy of less than 10 pm, preferably less than 5 pm, more preferably less than 2 pm, in at least one of the three axes X, Y, Z. Corrective machining equipment according to any 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 equipment according to any one of claims 1 to 9, characterized in that the machining machine (200) comprises a system for releasing, after corrective machining, at least a portion of the metal parts (10, 10') from their support (2). Corrective machining equipment according to any 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 forceless machining means (100), in order to orient the electromagnetic wave (110) emitted in the 3 dimensions XYZ.Machining equipment according to any one of claims 1 to 11, characterized in that said control system for said forceless machining means (100) is arranged to machine at least a portion of the metal parts (10, 10') according to different machining steps. Corrective machining equipment according to any 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 10,000 seconds. Corrective machining process for microtechnical metal parts (10, 10') previously produced by a LIGA process, said process comprising the different steps (AF) consisting of: A: to supply, on a parts support (2), metal parts (10, 10') previously produced by a LIGA process, B: to equip oneself 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 frame (X1Y1Z1) used during the production of the metal parts (10, 10') by the LIGA process a target geometry and at least one predetermined reference position (x1 , y1 , z1) specific to each metal part (10, 10') positioned on said part support (2); D: recognize, in at least one corrective machining datum (XYZ), in relation to said manufacturing datum (X1Y1Z1) the 3D geometry and positioning of the metal parts (10, 10'), previously carried out by LIGA process, and determine a correction of the geometry to be made with respect to said target geometry and said reference position (x1, y1, z1) recorded using said vision system (120) and said calculation unit (130); E: to perform corrective machining steps on said metal parts (10, 10') by said forceless 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 frame (XYZ) with respect to said metal part (10, 10') to be corrected, in order to carry out the corrective machining according to said correction of the geometry determined in step D to obtain said target geometry; F: release at least one of said metal pieces (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 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.

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

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

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

19. A 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 corrective machining reference frame (XYZ), said corrective machining positioning mark being linked to at least one positioning mark of manufacturing from which is defined the reference position (x1 , y1 , z1 ) of each part in the manufacturing reference frame (X1Y1Z1 ).

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

21. A metallic microtechnology part (10, 10') obtained by the process according to any one of claims 14 to 20, and having at least one portion which exhibits a difference of less than 2 µm, preferably less than 1.5 µm, between the dimensions of the corrected part and the target geometry.

22. A metallic microtechnology part (10, 10') according to claim 21, characterized in that at least two surfaces of said metallic microtechnology part (10, 10') have been corrected by the process according to any one of claims 15 to 20.

Images