Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P1/00—Details of instruments
  • G01P1/02—Housings
  • G01P1/023—Housings for acceleration measuring devices
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
  • H05K3/306—Lead-in-hole components, e.g. affixing or retention before soldering, spacing means
  • H05K3/308—Adaptations of leads
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
  • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
  • H01L2224/42—Wire connectors; Manufacturing methods related thereto
  • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
  • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
  • H01L2224/4805—Shape
  • H01L2224/4809—Loop shape
  • H01L2224/48091—Arched
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/00011—Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K1/00—Printed circuits
  • H05K1/02—Details
  • H05K1/0271—Arrangements for reducing stress or warp in rigid printed circuit boards, e.g. caused by loads, vibrations or differences in thermal expansion
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
  • H05K2201/10613—Details of electrical connections of non-printed components, e.g. special leads
  • H05K2201/10954—Other details of electrical connections
  • H05K2201/10962—Component not directly connected to the PCB
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/20—Details of printed circuits not provided for in H05K2201/01 - H05K2201/10
  • H05K2201/2045—Protection against vibrations
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49002—Electrical device making
  • Y10T29/49117—Conductor or circuit manufacturing
  • Y10T29/49204—Contact or terminal manufacturing

Definitions

• the invention relates to electronic sensors comprising an electromechanical microsensor cell such as a micro-accelerometer, and it relates more particularly to the mounting of the microsensor cell proper in a housing also comprising one (or more) printed circuit board. carrying the electronic processing circuits associated with the microsensor cell.
• an accelerometer is very sensitive to vibrations and shocks and it would provide an electrical signal that is difficult to exploit if a parasitic signal due to vibrations of the object whose acceleration is to be measured is superimposed on the acceleration measurement itself. called.
• vibrations and shocks could damage the sensor, which would be even more harmful.
• the acceleration measurement is not the only case where vibrations and shocks cause breakdowns or measurement difficulties, but it constitutes a typical case to which the invention is particularly applicable. Sensors of other physical sizes, produced by micro-machining, can typically be affected.
• the cell is then mounted in a housing with the interposition of a shock and vibration absorbing element.
• the cell is wedged in the casing by elastomer wedging blocks whose mechanical damping properties are adapted to the shocks and vibrations to be filtered, and the cell is not in direct physical contact with the casing.
• a possible electrical connection mode between the microsensor cell and the electronic card is shown in FIG. 1 in section and in FIG. 2 in top view.
• the cell 10 with its electrical connection pins 12, is contained in a housing 20 closed by a cover 22; it is held in place by damping blocks 24 (in principle made of elastomer) which support it by absorbing the shocks and vibrations transmitted by the housing.
• the housing can be fixed on an object on which a measurement is made, the fixing being possible by any means and not being shown.
• the cell is located on the side of the rear face of an electronic card 30 which carries on its front face components 32 and printed conductors 34; the card 30 is pierced with holes 36 in which freely engage (without physical contact), from the rear of the card, the connection pins 12 of the cell; the ends of the pins are connected, by welded wires 14, to conductive pads forming part of the printed conductors 34 of the front face of the card; the wires are welded on one side to the end of the spindle and on the other to a respective stud associated with this spindle; the wires 14 are not straight but they are bent so as to act as a spring having a low stiffness in all directions (a straight wire would have a high stiffness in the direction of this straight line).
• the wires are typically made of bare gold or aluminum or else copper insulated by plastic sheath, or copper or silver coated with enamel insulator, etc.
• the diameter of the conductive wire is typically 50 micrometers and its length is a few millimeters.
• the wire must be preformed before or during the welding operation to give it the curved shape which ensures low stiffness in all directions, and this preforming operation, like the operation of holding the wire during welding, is difficult to achieve. It has been found that the modules thus produced are excessively sensitive to vibrations, which prevents correct measurement.
• Another way to make the connection between the sensor and the card can be to use a flexible printed circuit board as is done in printers, camcorders, etc.
• the invention proposes to provide a solution at least partially improving the known solutions.
• the sensor according to the invention comprises a housing, a microsensor cell wedged in the housing by damping blocks, and an electronic card comprising electronic circuits associated with the cell, the cell comprising connection pins, flexible conductive connections being provided. between the connection pins and the printed conductors of the card, this sensor being characterized in that each conductive link comprises a thin flexible metallic strip machined by cutting, extending between the pin and a printed conductor passing near the pin, the strip being electrically connected on one side to the conductor and on the other to the spindle and comprising between the conductor and the spindle an arc-shaped section parallel to the plane of the card and extending freely above the card with a space between the ribbon and the card.
• the ribbon cut from a metal sheet, is preferably electrically connected to the pin and to the printed conductor by soldering.
• the arcs (preferably arcs of a circle) corresponding to different conductive connections are preferably identical. They preferably extend over at least 180 °, and preferably over about three quarters of a turn.
• the width of the ribbon at the location of the arc is preferably less than the width of the ribbon in sections of ribbon extending between the arc and the pin or between the arc and the conductor of the printed circuit.
• the width of the arc may be a few tens of micrometers, for example 70 to 100 micrometers for a sheet of thickness about 50 micrometers; this small width and this small thickness, combined with the curvature of the arc, give a very low stiffness to the conductive bond in all directions, and it should be noted that the stiffness in the direction perpendicular to the sheet is much lower than that which would be necessary to support the cell, the latter being completely supported by the damping blocks.
• the links are therefore not means of supporting the cell but means of transmitting electric voltages and currents which do not transmit mechanical stresses to the cell.
• One end of each conductive connection preferably comprises a ring in the center of which passes the connection pin of the cell.
• the other end of the link may also include a ring through which passes a pin welded to the printed conductor, the thin metallic strip then being welded to this pin.
• the material of the metal foil is preferably an alloy of copper and beryllium chosen because of its elasticity properties greater than those of copper and its electrical conductivity close to that of copper. The manufacturing process proposed according to the invention is particularly economical because it uses collective machining of a set of electrical connections.
• a method of manufacturing a sensor comprising a housing in which are mounted a microsensor cell wedged in the housing by damping blocks and a printed circuit board associated with the cell, the method comprising the operations following: - machining by cutting a thin and flexible metal sheet so as to form in this sheet several conductive connections in the form of a narrow ribbon having a very low stiffness in all directions, each connection comprising a section curved in an arc in the plane of the leaf, these connections being intended to each connect a respective connection pin of the cell to a printed circuit conductor of the card which passes near the pin, the various connections being secured to each other by bridges forming part of the sheet, - place the cell near the card, and solder each link on one side to a pin and the other to a corresponding conductor leaving a free space above the card between the arcuate section of the narrow ribbon and the card, - and cut the bridges between connections to separate them from each other.
• the machining of the sheet is preferably a chemical machining by photolithography.
• the cutting of the sheet preferably includes the cutting of openings at the locations where components are placed on the card, the sheet being placed on the card on which components have been previously welded. Not only the components but also conductive pins can be soldered to the card, and the conductive link is soldered to the free end of these pins.
• the narrow ribbon can have ring-shaped endings and in this case we thread this ring around a cell pin or a conductive pin welded on the card, before soldering the ring on the pin or the pin.
• FIGS. 1 and 2 The general constitution of the sensor according to the invention is that of FIGS. 1 and 2 with the exception of the conductive connections between pins 12 of the cell and conductors 34 of the printed circuit board, and this general constitution will therefore not be described again.
• the cell is placed at the rear of the card and the pins cross the card to pass on the side of the front face, but we could also have the cell on the side of the front face (the one which carries electronic components), the pins do not need to pass through the card.
• FIG. 3 represents a conductive link 50 put in place (but not welded) above a connection pin 12 of the cell and a conductive pad 34 printed on the card; the link 50 is intended to connect this pin to this pad.
• the hole 36 drilled in the card and in which the pin 12 can freely be threaded near the stud 34 is not shown in FIG. 3, being masked by a part of the conductive link which covers it.
• the conductive link is a very low stiffness link, which is not intended to physically support the weight of the cell, and all of the conductive links associated with the different pins cannot support this weight.
• the weight of the cell like the acceleration forces which it can undergo, is entirely supported by the damping blocks 24, made of elastomer, of FIG. 1.
• the individual connection 50 is cut, preferably by chemical machining, from of a photolithographed drawing, in a thin flexible metallic sheet.
• the thickness is chosen to give a very low stiffness to the connection in the plane perpendicular to the metal sheet, that is to say, in operation, in the plane perpendicular to the printed circuit board.
• the order of magnitude of the thickness is 50 micrometers.
• the sheet is made of elastic material and is a very good conductor of electricity.
• the preferred material is an alloy of copper and beryllium, such as the alloy CuBe2.
• the shape of the cut link is a narrow ribbon (the width can be of the order of 70 to 100 micrometers, for example over the major part of the length of the ribbon), the small width being chosen to give a very low stiffness to the link in the plane of the sheet.
• the narrow ribbon is not straight but has a main part 51 curved in an arc parallel to the plane of the sheet.
• the arc is preferably an arc of a circle, and it extends over a large sector, preferably at least 180 °, and in this example about three quarters of a turn.
• the length of the arch can be of the order of 1 cm.
• the circular arc is shown centered on the pin 12 in the example drawn in the figures, but this is not compulsory and the pin is not even necessarily located inside the curvature of the arc.
• This arc shape extending over a large sector is intended to give the conductive connection a very low stiffness in all directions of the plane of the sheet.
• One end of the ribbon portion 51 in an arc is connected by a first section 52 of small width (for example the same width as the arc of a circle) to a second section 53 wider (order of magnitude: approximately 300 or 400 micrometers) which constitutes the first termination of the link.
• the section 52 extends radially from the center of the circular arc.
• Another end of the ribbon portion in an arc is connected by a third section 54, here also a radial section and of small width, to a fourth section 55 which constitutes a second termination of the connection.
• the sections 52, 54 preferably leave at a right angle from the ends of the section 51. Their function is to allow the latter to work essentially in torsion and not in bending, in the manner of a helical spring.
• the ribbon in an arc and the various sections are configured so that the first termination can come above the conductive pad 34 when the first termination is above the pin 12.
• the second termination 55 is shaped as a ring surrounding the pin 12 ; the width of the ring is preferably greater than the width of the section 54.
• the first termination 53 is shown in FIG. 3 as being a linear strip whose end can be welded to the conductive pad 34; we will see later that this termination 53 can also be in a ring.
• the solder between the first termination and the conductive pad can be indirect in the sense that one can provide that a conductive pin is inserted into a hole in the card in the center of the pad 34, this pin being welded to the conductive pad and the first termination being then welded to the upper part of the pin.
• Figures 4 and 5 which are perspective views of the front or upper face of the card 30, represent the latter solution.
• a conductive metal pin 38 has been welded to the center of the printed pad (in principle after inserting the pin into a hole in the center of the pad 34), at the same time as the various components 32 of the latter were welded onto the card.
• the second termination 55 is threaded on pin 12 ( Figure 4) after the card has been placed above the cell 10 wedged in the housing by the damping blocks; the first termination is placed above the pin 38. Then, the welding operation is performed (FIG. 5), on the two terminations.
• the ring 55 is welded over its entire periphery to the pin 12; the end of the termination 53 is welded to the conductive pin.
• the narrowing of width between the ring 55 and the section 54, or between the termination 53 and the section 52 confines the weld to the ring 55 and the termination 53 and prevents the weld from wetting the sections 52 and 54 of small width, which would have the consequence of increasing the rigidity of the connection.
• the angle formed by the bar 53 with the section 52, and the length of the bar 53 depend on the configuration of the printed circuit on the card and more precisely on the position of the conductive pad relative to the pin to which it is desired to connect it. .
• the stiffness of the connection is very low in the three dimensions and a clearance is possible because the hole 36 has a larger diameter (for example greater than one millimeter) than the diameter of pin 12 and the fact that a vertical space (for example 1 millimeter) is provided between the ribbon in an arc 51 and the card.
• the advantage of using a conductive pin 38 is that a free space can be provided between the conductive connection and the card over the entire length of the ribbon constituting the connection.
• FIG. 6 represents the collective production of the sheet for making and simultaneously mounting the different conductive laces on the different pins of the cell.
• the drawing cut from the sheet includes the various connections, correctly positioned with respect to each other taking into account on the one hand the relative position of the different pins of the cell and the position of the conductive pads to which these pins are to be connected.
• the sections 51 in an arc
• the sections 52, 54 connected to the arc
• the rings 55 are preferably all identical from one link to another, even if they have different orientations from one link to another, in order to minimize structural asymmetries, particularly in the case of an accelerometer which is a very sensitive type of sensor to the asymmetries of constraints it undergoes.
• the connections are connected to a frame 57 which keeps them in place during the welding operation: bridges 58 between the terminations and the frame 57 serve for this maintenance. After the welding operation, these bridges are removed by cutting.
• the metal sheet in the form of a rectangular peripheral frame 57 inside which are arranged only the connections 50 and the bridges.
• the cut metal sheet is constituted by a rectangle having substantially the same surface as the electronic card and which comprises on the one hand the cutouts of connections and bridges and on the other hand cutouts around each component of the card so that the sheet can be placed on the card without being hindered by the components.
• the solid parts of the card, between the cutouts provided around the components, then constitute the frame to which the bridges are attached.
• the thin metal sheet can be cut by photolithography in a continuous ribbon to make not only all the conductive connections between the cell and the card of a sensor but also the connections of a series of sensors in a continuous mass production, this which further reduces the manufacturing cost.
• the operations of placing, welding and cutting the bridges can be carried out by an automatic machine.
• the conductive termination 55 in this example, provision has been made for the conductive termination 55 to be a ring, the internal cutout of which is a grooved shape facilitating placement on the spindle at a determined height (the ring gets stuck on the spindle); it was further provided that the termination 53 also includes a ring shape (also grooved if desired) threading on a conductive pin such as pin 38, previously welded on the card.
• the section 54 which connects the ring 55 to the circular arc 51 is turned radially towards the inside of the circular arc, and the pin 12 is in the center of this arc.
• section 55 could leave in another direction, even towards the outside of the arc or even in the extension of the arc, the spindle not being in the center of the arc nor even necessarily inside the arc.

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• 2003
  • 2003-11-18 FR FR0313495A patent/FR2862413B1/fr not_active Expired - Fee Related
• 2004
  • 2004-10-27 WO PCT/EP2004/052680 patent/WO2005050227A1/fr not_active Application Discontinuation
  • 2004-10-27 US US10/571,933 patent/US7400514B2/en active Active
  • 2004-10-27 EP EP04818818A patent/EP1685411A1/de not_active Withdrawn

Non-Patent Citations (1)

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