FR2721145A1 - Apparatus for mounting a device comprising a grid network for ball-shaped terminals for testing electronic circuits. - Google Patents

Abstract

The devices comprising a grid network for ball-shaped terminals are mounted in a test and accelerated aging socket which has an upper surface (24) with windows (23) for the terminals depending on the device. Contact fingers mounted on the base of the socket extend through a bending plate to the windows from the opposite side of the top surface. When the bending plate is moved laterally with respect to the upper surface, the ends of the contact elements are brought into contact with the terminals. The ends of the contact elements are urged to come into contact with the terminals between the center of the bead-shaped terminal and the surface of the grating network, hence the maintenance of the device in the socket.

Description

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  The present invention relates to an apparatus

  for mounting and testing electronic devices.

  More particularly, it relates to a socket device for maintaining and making electrical contact with the input / output terminals of devices comprising a grating network for bead-shaped terminals during the tests, accelerated aging, etc. Advances in microelectronics technology tend to develop device chips that take up less space while performing more functions. As a result, the number of electrical interconnections between the chip and all of the external circuits necessary for the circuit of the chip to communicate with the outside world increases and that the physical dimensions of such an interconnection must decrease. In order to provide electrical communication between the chip and all of the external circuits, the chips are generally contained in a housing or block which supports the interconnection wires, the pads, etc., on one or more of its external surfaces . In order to reduce the overall length of the wires going from the chip to the set of external circuits and to provide a suitable spacing between the input / output terminals on the block, high pin counting devices are generally mounted in blocks in which the input / output terminals are arranged in the pattern of a grid on one face of the block. The terminals may be in the form of pins extending from the block (generally called a pin grid assembly) or contact pads placed on the surface of the block. To physically fix the chip to a substrate and make the electrical connection between the pads of its terminals and similar interconnection pads on the surface of a substrate such as a circuit board, etc., on which the block must be mounted, a small drop or a solder ball,

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  etc., is attached to each stud on the device block. Since the drop of solder forms a projection similar to a ball which extends from the stud, devices of this kind are generally called a grid network for balls. While the term "grid array device for balls" is generally applied to a device block which has substantially spherical contacts extending from one of its faces, the term also applies to other structures. For example, bare chips (not encapsulated) sometimes include a network of contact grids in the form of a ball for mounting in a block. However, at some stage of manufacturing, the bare chip with ball-shaped contacts is fairly well described as a grid array device for balls. In a similar way, the finished chips are sometimes equipped with terminal pads on a surface with solder deposits similar to a ball forming the interconnections on the terminal pads. The chip is then inverted and fixed directly to a corresponding pattern of the interconnection pads on a substrate. When heated, the solder balls are subjected to a reflux forming the electrical and physical connections. This process (which is sometimes called in English technology "flip-chip") obviously uses devices which one can call devices in network in grid for balls. By

  Consequently, for the purposes of this description, the

  expressions "grid array for beads" and "grid array device for beads" mean any structure, including device blocks, "flip-chips" and bare cubes, carrying a multitude of interconnections having substantially the shape of 'a ball on one of their faces which are arranged in a pattern substantially similar to a grid. The ball-shaped terminals are substantially spherical and arranged on one face of the device block in a pattern

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  predetermined. As the ball-shaped terminals are substantially spherical and of uniform size, each terminal has a geometric center which is distant from the surface of the block on which the ball-shaped terminal depends and the geometric centers of the terminals are located substantially in a plane parallel to the block surface

  on which the terminals depend. This plan (or corresponding plan-

  weighting for each individual terminal) is designated here by center, axis or extended axis of the terminal in the form of

ball.

  Many electronic devices are subjected to accelerated aging and testing at some point in the manufacturing process. For accelerated aging and testing, the device must be removably mounted on a test device that provides the electrical connection with each of the input / output terminals while the device is functionally tested and subjected to an evaluation. In many cases, the device is subject to the conditions of a hostile environment (such as heat, etc.), as well as to electrical constraints in order to assess and ensure the full functionality of the finished device. In order to provide effective accelerated aging and testing, the apparatus for accelerated aging and testing must allow rapid and easy insertion and removal without damaging the device, the block of the

  delicate device or ball-shaped terminals.

  However, the very characteristics of the grid array device for balls that make it attractive as a device structure (i.e., very small contacts tightly grouped on a hidden side) make it extremely difficult to mount it reliably in a test socket without damaging the

structure of the device.

  In conventional test structures, the grid array device for balls is positioned on an interconnection substrate comprising studs

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  interconnection in a network corresponding to the pattern of the grid network for balls. The grid array device for balls is placed on the substrate so that the terminal balls are individually in contact with interconnection pads on the substrate under test. However, to maintain the network device in the correct position and orientation for the test, a cover must be used which encloses the device and keeps the network aligned

  and in contact with the interconnection pads.

  Unfortunately, the cover interferes with the correct circulation of cooling air around the device and prevents the use of heat sinks even if the device can be designed to operate only in conjunction with a particular heat sink. Since it is also difficult to handle the covers, these can damage the device and generally prevent automated loading and unloading of the sockets

test.

  The present invention avoids the difficulties of the prior art by providing a mounting housing

  or socket with the upper end open.

  No cover is required. Thus, the upper face of the device under test is available for the attachment of a heat sink or is open to cooling air, etc. In addition, since the top of the socket or mounting housing is open, the devices to be tested can be inserted and removed by automated processes without fear

  damage the mounting devices or device.

  The socket or mounting housing of the present invention comprises a support element having an upper face which includes a multitude of windows for receiving the network of balls of the interconnection terminals depending on the face of the network in grid for balls. The socket also includes a basic element in which are anchored a multitude of pins

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  or axially elongated contact fingers. One end of each contact finger extends through the base to provide a mounting tail that can be welded

  to an accelerated aging panel or the like.

  The opposite end of each finger projects into one of the windows. The central part of each finger (between the free end and the base) extends through an opening made in a bending plate mounted between the base and the support element. The bending plate can be fixed or movable laterally with respect to the support element in order to move the free ends of the contact fingers with respect to the windows. The end portion of each free end is curved or arched so as to define a contact tip at the very end of the free end which deviates from the axis of the finger. The fingers are mounted so that in the open configuration, the free end portions of the contact fingers are adjacent to one side of their respective windows. When a lattice grating device for balls is placed on the upper face of the support element, the balls protrude in the windows. In the preferred embodiment, a cam is used to move the flexure plate laterally, hence the simultaneous and uniform movement of the free ends of the contact fingers in the same direction. The end portions are thus urged to come into contact with the balls of the terminals occupying the windows. The extreme portion of each finger (which is deviated from the axis of the finger) is placed in the vicinity of the upper part of the window. Thus, when the finger is moved by the bending plate, the end contacts the terminal ball located above its horizontal axis. The fingers thus provide individual electrical contact with each ball and, as they are in contact with the balls located above their axis (between the center of each ball and the face of the

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  they depend on), they hold the balls in their respective windows and thus catch the grid network device. As the grid network device is held in place by the end portions which are in contact with the balls above their axes, the size of the balls can vary within certain limits without affecting the gripping effect of the contact fingers. Because of the simplicity of design and operation, the socket devices of the present invention can be made from a wide variety of materials available. Since the top of the socket is open, automatic methods can be used to load and unload the socket without damaging the devices or sockets and the top surface of the device is exposed for cooling and / or

  attachment to a heat sink.

  The present invention will be well understood

  during the following description made in connection with

  the accompanying drawings, in which: Figure 1 is an exploded perspective view of the assembly of a grating array device for balls with a preferred embodiment of the housing of the invention; Figure 1A is a partial enlarged view of the upper surface of the mounting housing of Figure 1; FIG. 1B is a partial view on a large scale of the surface of the grid network of the device of FIG. 1; Figure 2 is a partial sectional view of the mounting housing taken along lines 2-2, showing the position of the contact fingers when the housing is in the open state; Figure 3 is a partial sectional view of the mounting housing of Figure 1 taken along lines 2-2, showing the position of the fingers of

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  contact when a grid network has been inserted into a socket and the socket is in the closed position; Figure 4 is a partial sectional view of the mounting housing of Figure 1 taken along lines 4-4 of Figure 2; Figure 5 is a schematic representation of the relationship between the end portion of a contact finger as used in the invention and terminal balls of various nominal dimensions which extend from the surface of the device grid network; Figure 6 is a partial sectional view of an alternative embodiment of the mounting housing of Figure 1, in which the bending plate is held stationary and the upper support member is used to move the grating network device relative to the contact fingers; and FIG. 7 is a partial sectional view of the device of FIG. 6 showing the relative positions of the ends of the contact fingers and of the grating network device when the socket is

found in the closed position.

  The terms "mounting housing" and "socket" are used herein as synonyms to describe a device or apparatus for maintaining a grating array device for balls while providing electrical contact with each of the terminal balls. For clarity of illustration, the same reference numbers are applied to parts

identical in all drawings.

  The operational arrangement of a device 10 with a grid network for balls is illustrated in FIG. 1

  with the mounting housing according to the present invention.

  The grid network for balls of the device 10 has a lower face 11 (see FIG. 1B) on which are

  formed a multitude of terminals 12 of spherical shape.

  Terminals 12 are formed by depositing solder at predetermined locations on mounting pads

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  or the like (not shown) on the face 11 of the device. Various methods for forming such terminal beads are known and do not form part of the present invention. Such methods normally produce substantially spherical bodies (see Figure 5) which depend on the underside 11 of the grid array device. The balls 12 are generally solder which has been deposited and heated so as to contract to take the form of a ball under the effect of surface tension. Regardless of the manufacturing process, for reference purposes, the bead-shaped terminals that extend from the face of the grid array are referred to herein as

  terminal balls or ball-shaped terminals.

  The balls 12 are arranged on the underside of the device 10 in a predetermined pattern similar to a grid. To receive the grid array device for beads, the mounting housing of the present invention employs an upper support member 22 which has a plurality of windows 23 extending therethrough. The windows 23 are arranged in the form of a grid pattern adapted to the grid pattern of the ball terminals 12. To receive grid network devices having different dimensions, the upper face 24 of the support element 22 can include removable spacers 35 of various dimensions. The spacers 35 define the periphery of each particular network device and position this device to prevent its movement in the lateral direction relative to the upper face 24. The spacers 35 therefore give the assurance that each network is aligned with the dependent terminals 12 of its lower face 11 in correct framing and orientation with the windows 23 and can be modified as necessary for each size and shape of the device block. In the preferred embodiment shown in Figure 1, the socket of the invention is

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  formed by a multitude of components similar to a plate (which is described below in detail) contained inside a unitary housing 100 similar to a box, having an open upper part and a lower part. As shown in Figures 2, 3 and 4, the housing contains a basic element 21 which has a multitude of openings 30 placed substantially in alignment with the windows 23 of the support element 22. Each opening 30 has an internal shoulder 31 (see figure 4). A finger of

  elongated contact 40 is placed in each opening 30.

  In the preferred embodiment, each contact finger defines an axially elongated body of an electrically conductive elastic material such as nickel-plated steel or the like. The middle section 43 of each finger 40 is substantially enlarged to form shoulders 45 and 46 at its opposite ends. Therefore, when the contact fingers 40 are inserted into the base member 21, the tail portions 41 protrude through the openings 30 and the shoulders 46 rest on the shoulders 31. A gripping plate 25 having openings 32 and shoulders 33 in alignment and in correspondence with the openings 30 is fixed to the base element 21 and the shoulders 33. The upper portion 44 of each finger extends through an opening 32 and the shoulders 33 of the opening 32 are in contact with the shoulders 45 on the extended middle sections 44 of the contact fingers. Therefore, the contact fingers 40 are securely gripped and held in place

  in the base element 21 by the plate 25.

  The lower ends of the contact fingers 40 extend from the underside of the base support 22 to define the input / output tails 41. The tails 41 can be fixed in a suitable circuit board, to a board for accelerated aging, etc. Alternatively, other means for making contact

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  electric with all the circuits in the middle of

support can be used.

  The upper portion 44 of each contact finger 40 which extends above the middle section 43 projects into an opening 54 made in the bending plate 28 with its free end 42 ending in the window 23. In the mode of preferred embodiment, the free end portion 42 of each finger 40 is sufficiently elongated to define a generally central axis which is substantially perpendicular to the support surface 24 and extends in a window 23. However, the free end 42a is arched or curved so as to be deflected with respect to the central axis and extends into the window 23 in the direction of the surface of the support 24 but does not extend through the window 23 or the surface 24. To obtain the best results, end 42a should extend as close as possible

  from surface 24 without extending through it.

  However, only the end 42a must be above the axis of the ball-shaped terminal with

which is in contact.

  In the preferred embodiment, each window 23 has a small recess 23a which receives the end portion 42 of the contact finger 40. As shown in Figures 2, 3 and 4, the bending plate 28 is placed between the gripping plate 25 and the support element 22 but is free for lateral movement back and forth relative to the housing. As the middle sections 43 of the fingers 40 are securely anchored between the base element 21 and the gripping plate 25, the lateral displacement of the plate 28 causes a corresponding lateral displacement of the end portions

free 42 of contact fingers 40.

  A rotary cam 50 extends horizontally through the mounting housing near the end surface 29 of the flex plate. The cam 50 is fixed in the housing 100 at one of its ends 2721145 by a retaining member 53. The opposite end of the cam 50 is controlled by a lever 52. A lobe 51 extending from the cam 50 is brought into contact with the end surface 29 of the plate 28 when the lever 52 is moved in a first direction. Thus, the rotation of the cam 50 (anti-clockwise as shown in FIG. 2) subjects the bending plate 28 in the same direction to a cam effect (to the left of FIG. 2). The movement of the bending plate 22 thus drives the free end portions 42 in the same direction, extracting them from the recesses 23a and causing them to pass laterally through the window 23. It must be recognized that a rotating cam 50 is the currently preferred means for moving the plate 28. Other means such as wedge plates, ratchets, plungers, and rack and pinion arrangements, to name a few, can be designed to perform the function of the relative movement of drug. Thus the terms "cam" and "cam plate" are used here to describe any mechanical arrangement which has the effect of moving the upper portion 44 of the contact fingers in the lateral direction relative to the element of

support 22.

  The position of the upper portions 44 of the contact fingers 42 in the housing in the open state is shown in FIG. 2. In this position, the contact fingers 40 are either released or forcibly driven into the open position by the plate. bending 28. If necessary, a spring (not shown) can be placed between the housing 100 and the end of the plate 28 opposite the end 29 to ensure that the free end portions 42 are enclosed in the recesses 23a. Consequently, a grid system for balls can be placed with the terminals 12 in the form of a ball in the windows 23 by simply positioning the network in the correct position. As the free end portions 42 are

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  enclosed in the recesses 23a, the terminals 12 simply depend on the windows 23. Thus, no pressure of any kind is applied to

  any portion of the network 10 or terminals 12.

  In addition, no force is applied (other than by gravity) to any part of the socket by the block of the electronic device or the ball-shaped terminals. When the grid network device is fixed in place, the lever 52 is moved to rotate the cam 50 and bring the lobe 51 into contact with

  the end surface 29 of the bending plate 28.

  When the plate 28 moves (to the left in FIG. 2) under the effect of the lobe 51, the free end portions 42 of the contact fingers 40 move uniformly and simultaneously to be in contact with

  the terminals 12 depending on the windows 23.

  As best seen in FIG. 1A and as shown graphically in FIG. 5, the free end portions 42 of the contact fingers 40 are positioned so as to extend in the windows 23 near the surface 24 but do not 'do not extend above this surface. In addition, the free end portions 42 are arched so that the whole end 42a deviates from the vertical axis of the pin 40 in the direction of the terminal 12 to form

  a cut or hook at the end 42a of the finger 40.

  As shown in FIG. 5, the end 42a of the free end portion 42 must extend above the axis of the terminal 12. For illustration purposes, FIG. 5 indicates the relative position of the end 42a in contact with a ball-shaped terminal when the nominal diameter of the balls is 0.75 mm. This diameter can vary from approximately 0.9 mm to approximately 0.6 mm. Thus, the point of contact on the ball may vary slightly with the change in the diameter of the ball. However, as shown in Figure 5, where the end 42a of the free end portion 42 extends from at least 0.025 mm to about 0.050 mm above the extended axis (line

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  horizontal passing through the center of terminal 12), the point of contact between the end 42a of the finger

  contact 40 will be approximately five degrees (5) above

  above the extended axis of the terminal 12. Thus, since the device 10 is grasped and cannot move horizontally because of the spacers 35, the pressure exerted against the terminals 12 by the ends 42a of the contact fingers 40a a lateral force component as well as a small directed force component

  down. The device 10 is thus seized and insured

  jetti to the upper face 24 of the support element 22 by the lateral pressure, directed downwards, which is

  exerted on the terminals 12 by the fingers 40.

  The relative positions of the components of the mounting housing and of the grating network device when the housing is in the closed position are shown in FIG. 3. It will be noted that the lobe 51 of the cam 50 has driven the plate 28 to the left of Figure 3. The ends 42a of the contact fingers 40 have moved in the same direction until they are in contact with the surface of the terminals 12. As the bending plate 28 continues to move to the left, the middle section 44 of each finger 40 is bent until a contact pressure of about 35 grams is applied to each terminal. As the end 42a of the finger 40 is above the axis of each terminal 12, this pressure securely blocks the entire grid network device contiguous to the upper surface 24 of the mounting housing, and each finger 40 is in electrical contact with a terminal 12 for testing an electrical function, etc. However, a pressure in the range of about 35 grams is not enough

  to damage or dislodge terminals 12.

  After the test, the accelerated aging test or other procedure applied to the device 10, it is released by simply moving the lever 52 in the opposite direction, allowing the fingers 40 (and the springs, if there are any) to request plate 28

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  in the opposite direction and at the ends 42a to be enclosed in the recesses 23. The apparatus of the present invention therefore provides a bushing with zero insertion force for the mounting of lattice grating devices for balls for the purpose of and accelerated aging. The test device can simply be placed on the upper face of the mounting housing under the effect of gravity. No force of any kind is applied to the device block or to terminals 12 during insertion or removal. In the embodiment discussed in detail above, the bending plate 28 is moved laterally so that the free ends 42 of the contact fingers 40 come into contact with the balls 12 of the terminals. However, it will be noted that other arrangements can be used to move the balls 12 relative to the free ends

42 of the contact fingers.

  In the embodiment shown in Figures 6 and 7, the bending plate 28 is held in a fixed position and the upper support member 22 moves laterally so as to simultaneously drive the terminals 12 to put them in physical contact with the free ends 42 of each contact finger. In this embodiment, the upper portion 44 of each finger 40 extends through an opening 54 formed in the bending plate 28. The openings 54 are placed relative to the openings 32 so as to urge the free ends 42 of the fingers of contact in a direction which is offset from the openings 32. In the embodiment shown in Figures 6 and 7, the contact fingers are curved in the opposite direction in the section which passes through the bending plate 28 and the openings 54 of the plate 28 are placed so as to stress the

  ends 42 in the direction of the curvature.

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  It will be noted that the free ends 42 rest in the recesses 23a in the windows 23

  when the sleeve is in the open position.

  However, when the upper support element 22 is moved (to the right of FIG. 7), the ball-shaped terminals are simultaneously brought into contact with the free ends 42a of the fingers 42 as described above in connection with the embodiment in which the bending plate 28 is driven by a

  cam effect to move the contact fingers.

  Other arrangements for effecting relative movement

  will appear to the technician.

  When the socket is in the closed position, the ends 42a of the fingers 40 each exert a lateral force and directed downwards on the ball-shaped terminal at approximately five degrees (5) above the axis. The pressure exerted by each finger is limited so that there is no risk of damaging the terminals 12. Similarly, when the fingers 40 are driven (or the upper plate is removed) until the open position, the device 10 can be removed simply under the effect of gravity or with a vacuum pencil or the like. It should be noted that the present invention not only allows a completely zero insertion force and extraction force, no pressure of any kind is ever applied to the device except for the balls 12. done, the entire upper surface of the device is exposed because no cover is used. Cooling air can circulate on top or a heat sink can be applied to it. Furthermore, since the test devices can be loaded simply by a vertical movement under the effect of gravity, the test device of the present invention can be easily loaded and unloaded by a

automated equipment.

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  It should be noted more particularly that in all the configurations of the invention, the reaction forces caused by the engagement between the device and the socket are contained in the body of the socket housing and not transmitted to the accelerated aging wafer. It will be noted that the opening (or closing) of the socket by the movement of the ends 42 of the contact fingers with respect to the balls 12 can involve a large force. For example, a typical contact force is about grams which is exerted on each ball 12 by each finger 42. In blocks having a thousand or more terminal balls, the cumulative contact force which is applied is greater than thirty (30 ) kilograms. This is an important force to be reckoned with because an accelerated aging insert, etc., can have a multitude of sockets and each

  socket is repeatedly loaded and unloaded.

  However, as the contact fingers are moved simultaneously with respect to the ball terminals by the rotation of a carriage, all the opening and closing forces (and their reaction forces) are contained in the socket. In addition, the fingers are each individually in contact with a terminal. Thus, only a force of about thirty grams is applied to any of the terminals. No significant force is ever applied to the device block or to the accelerated aging support wafer. On the contrary, all the forces (and reaction forces) applied are contained in the housing of the socket. It will be readily recognized that the materials used for the manufacture of the mounting housing of the present invention may be variable, depending on the application. Similarly, the physical dimensions and the shape of the components can be chosen to take into account any particular grid system device. For example,

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  the contact fingers 40 are shown as axially elongated metal strips, cut or stamped from a flat ribbon. However, the fingers 40 could be formed of a wire and take any configuration without departing from the principles of the invention. Likewise, the fingers can be anchored in the sleeve by any suitable means. If the sleeve is to be used for accelerated aging, heat-resistant materials must of course be used. The embodiment is particularly attractive for use in hostile environments, because in the preferred embodiment, very few moving parts are used, and the opening and closing functions can be easily automated. Thus, the preferred structure is extremely reliable and

  functional in extensive repetitive use.

  The present invention is not limited to the embodiments which have just been described, it is on the contrary subject to modifications and

  variants which will appear to those skilled in the art.

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Claims (17)

  1 - Apparatus for mounting a device (10) comprising a grid network for balls, characterized in that it comprises: (a) a support element (22) having a support face (24) with a multitude windows (23) arranged in a pattern to correspond and receive terminal-shaped balls (12) depending on one face of a device comprising a grating network when this device is placed on the support face of the element support; (b) a base element (21); (c) a bending plate (28) having openings (54) which substantially correspond to the windows placed between the base member and the support member and intended to move laterally relative to the support member; (d) a multitude of elongate contact elements (40) anchored in the base element, each having an interconnection end (41) and a free end portion (42) disposed on opposite sides of a central section (43), the central section projecting through an opening in the bending plate and the free end portion being placed in a window of the support element; and (e) a cam (50) intended to move the position of the flexion plate in the lateral direction with respect to the support element and thus urge the free end portions to bring them into contact with the balls of the terminals between their axis and face on which they depend.   2 - Apparatus according to claim 1, characterized in that the free end portion (42) of each of the contact elements (40) has a generally central axis and the whole end (42a) of the end portion is deviated from the 'axis generally central. 19 2721145   3 - Apparatus according to claim 2, characterized in that each end portion (42) extends to a window (23) of the support element   (22) but does not extend therethrough.   4 - Apparatus according to claim 1, characterized in that the cam (50) is in contact with   the bending plate (28) and moves it.   - Apparatus according to claim 1, characterized in that the cam (50) is in contact with   the support member (22) and moves it.   6 - Apparatus according to claim 4, characterized in that it further comprises a spring means, for biasing the bending plate (28) in the lateral direction relative to said support member (22).   7 - Apparatus according to claim 5, characterized in that it further comprises a spring means for biasing the support element in the   lateral direction with respect to the bending plate.   8 - Apparatus according to claim 2, wherein the entire end (42a) of the free end portion of each of the contact elements (40) extends to a window (23) formed in said support element (22) a sufficient distance to be in contact with a terminal (12) placed in the window between the center of the terminal and the face of the device whose depends on such a terminal.   9 - Apparatus according to claim 1, characterized in that it further comprises spacers (35) removably fixed by being adjacent to the support face to at least partially define the periphery of a grid network device for balls to be placed on the support face. 10 - Apparatus for mounting a device (10) comprising a grid network, characterized in that it comprises: 2721145   (a) a support member (22) having a support face (24) with a multitude of interior windows (23) which are arranged in a pattern to match and receive terminal shaped balls (12) which depend on the face of a device comprising a grid network when this network is placed on the support face of this support element; (b) a base element (21); (c) biasing means having openings which substantially correspond to the windows placed between the base member and the support member; (d) a multitude of elongate contact elements (40) anchored in the base element, each having an interconnection end (41) and a free end portion (42) disposed on opposite sides of a central section (43), this central section projecting through an opening made in the biasing means and the free end portion defining a generally central axis with the free end portion deflected from this central axis and placed in a window of the support element; and (e) means for moving the portions   free extremes compared to the window.   11 - Apparatus according to claim 10, characterized in that each end portion (42a) extends to a window (23) of the support element   (22) but does not extend through said window.   12 - Apparatus according to claim 10, characterized in that it further comprises spacers (35) removably attached by being contiguous to the support face (24) to at least partially define the periphery of the devices comprising a network in grid to be placed on the support surface.   13 - Combination, characterized in that it comprises: (a) a device comprising a grid network for balls having a first face and a 21 2721145   multitude of terminal balls (12) depending on the first face in a predetermined pattern, each of the ball-shaped terminals defining a geometric center spaced from the first face; and (b) a mounting apparatus comprising: (i) a support member (22) having a support face (24) with a multitude of windows (23) arranged in a pattern to match and receive balls dependent on the first face of the device; (ii) a basic element (21); (iii) a bending plate (28) having openings (54) which substantially correspond to the windows placed between the base member and the support member; and (iv) a multitude of elongate contact elements (40), each having an interconnection end (41) and a free end portion (42) disposed on opposite sides of a central section (43), the section central projecting into an opening of the bending plate and the free end portion being placed in one of the windows of the support element and ending between the first face of the grating network and the geometric center of a ball terminal (12). 14 - Combination according to claim 13, characterized in that the free end portion (42) of each of the contact elements (40) has a generally central axis and the very end of the portion 22 2721145   extreme (42a) is deviated from this axis generally central.   - Combination according to claim 14, characterized in that each free end portion (42) extends to a window (23) of the support element   (22) but does not pass through said window.   16 - Combination according to claim 13, characterized in that it comprises means for moving the free end portions relative to the Windows.   17 - Combination according to claim 16, characterized in that the displacement means comprises a rotary cam (50) contiguous to the bending plate (28) which, when it rotates, acts mutually with the bending plate to move this plate   laterally with respect to the support element.   18 - Combination according to claim 17, characterized in that the displacement means comprises a spring placed so as to urge the plate   bending laterally with respect to the support element.   19 - Combination according to claim 16, characterized in that the displacement means comprises a rotary cam (50) contiguous to the support element (22) which, when it rotates, acts mutually with the support element for the move sideways by compared to the bending plate.   - Combination according to claim 19, characterized in that the displacement means comprises a spring placed so as to urge the support means (22) laterally relative to the plate bending (28).   21 - Method for mounting a device (10) comprising a grid network for balls having a multitude of terminal balls (12) which extend from one face (24) of the network, characterized in that it comprises the stages consisting in: 23 2721145   (a) providing a support plate with a top surface and a multitude of windows (23) arranged in a given pattern; (b) positioning one end (42a) of an elongated contact element (40) in one side of each window and being adjacent to this side; (c) positioning a device comprising a grating array for balls on the upper surface with the dependent terminal balls in the windows; and (d) moving said end of each of the elongated contact elements to bring it into contact with the dependent terminal in the window occupied by the end of this contact element, hence maintaining   of the device against the upper surface.   22 - The method of claim 21, characterized in that it comprises the step of defining at least a portion of the periphery of the device placed on the upper surface with a spacer (35) removably attached by being   contiguous to the upper surface.