JP4170259B2 - Ball grid array device mounting device - Google Patents

Description

  The present invention relates to a ball grid array device mounting apparatus for mounting and testing an electronic device. More specifically, the present invention relates to an input / output terminal of a ball grid array apparatus during testing and burn-in. The present invention relates to a mounting device for a ball grid array device corresponding to a socket device for holding and electrically connecting.

  Advances in microelectronic technology tend to develop device chips that can perform more functions in less space. Since the number of electrical interconnections required for circuits within a chip between the chip and external circuits to communicate with the outside world increases, the physical space for this interconnection must be reduced. In order to make electrical contact between the chip and external circuitry, the circuit chip is usually housed in a housing or package that supports interconnect leads, pads, etc. on one or more external surfaces. ing. In order to shorten the overall length of the leads from the chip to the external circuit and form an appropriate space between the input / output terminals of the package, a high pin count device is attached to the package, and the input / output terminals are It is arranged in a grid pattern on one side of the package. The terminals may be in the form of pins protruding from the package (usually described as a pin grid array or PGA) or in the form of contact pads on the surface of the package. In order to physically fix the chip to the substrate and to electrically connect between pads on the surface of the substrate such as a circuit board to which the package is to be attached and between similar interconnection pads, solder etc. When the droplet is dropped, it is fixed to each terminal pad of the device package. Since the solder droplets form spherical protrusions on the terminal pads, such a device is called a ball grid array (BGA) device.

  The term “ball grid array device” is generally applied to device packages with substantially spherical contacts protruding from one side, but the term also applies to other structures. The For example, a bare (uncoated) chip may be provided with a grid array of spherical contacts for mounting in a package. However, at some point during manufacture, bare chips with spherical contacts are often described as ball grid array devices. Similarly, the finished chip may be provided with terminal pads on one surface and spherical interconnects formed on the terminal pads. The chip is then inverted and attached directly to the corresponding pattern of interconnect pads on the substrate. When heated, the spherical solder flows again, forming an electrical and physical connection. This process (sometimes referred to as “flip chip” technology) clearly uses so-called ball grid array devices. Therefore, in this specification, “ball grid array” and “ball grid array device” are a plurality of elements arranged in a substantially grid pattern on one side, such as a device package, flip chip, and bare die. Any structure that forms a generally spherical connection is meant. The ball terminals are substantially spherical and are arranged in a predetermined pattern on one surface of the device package. Since the ball terminals are substantially spherical and are substantially uniform in size, the geometric center of each ball terminal is spaced from the surface of the device package. The ball terminal depends from the package, and the geometric center of the ball terminal is substantially in a plane parallel to the surface of the device package from which the ball terminal depends. This plane (or a plane corresponding to each ball terminal) is referred to herein as the center, center line, or center extension line of the ball terminal.

  Many electronic devices undergo burn-in testing during the manufacturing process or at some stage after fabrication. To perform a burn-in test, the device must be attached to and removed from the test fixture. With the fixture, each terminal of the input / output terminals is electrically connected, and the function of the device is tested and evaluated. In many cases, devices are exposed not only to electrical stress but also to harsh environmental conditions (eg, heat, etc.) in order to verify the integrity and functional integrity of the finished device. To perform an effective burn-in test, the device is mounted in a fixture that can be quickly and easily inserted and removed without damaging the device, device package or sophisticated ball terminals. It must be able to be taken out. However, a feature of the ball grid array device that makes it attractive as a device structure (e.g., very small contacts densely placed on a hidden surface) is the ability to fit in a test socket without damaging the device structure. It is extremely difficult to install securely.

  In the conventional test socket construction, the ball grid array is placed on an interconnect substrate having interconnect pads in the array corresponding to the ball grid array pattern. The ball grid array device is placed on the substrate such that the terminal balls are in individual contact with the interconnect pads on the test substrate. However, in order to perform the test, the ball grid array device must be maintained in the proper position and orientation, so that the device can be entraped using a lid or cover to align the ball grid array with the interconnect pads. Maintain contact. Unfortunately, the trap lid prevents proper circulation of cooling air around the device, thus eliminating the use of a heat sink even if the device is designed to operate only in conjunction with a particular heat sink. Such lids or covers are difficult to operate, can damage the device and prevent automated loading and unloading of test sockets.

  The present invention eliminates the disadvantages of the prior art by providing an opening at the top of the mounting housing or socket. A lid, cover, etc. are not required. Thus, the top surface of the device is used to attach to the heat sink during testing and is open to cooling air and the like. Furthermore, since the socket, ie the top surface of the mounting housing, is open, the device to be tested can be inserted or removed by an automated process without the risk of damaging the device or the mounting device.

A ball grid array device mounting apparatus according to the present invention includes a base member and a terminal ball fixed to the base member and having an interconnecting end on one side in the longitudinal direction, and the other hanging from the lower surface of the ball grid array device. A plurality of elongate contact members having a free end portion configured to apply a laterally downward pressure by contacting from a side to a position exceeding a horizontal line passing through the center of the lower surface side , and a free end portion of the contact member. A ball grid array device mounting device comprising: a moving member that opens and closes and moves a free end portion of the contact member to and from a terminal ball of the ball grid array device, the center of the terminal ball of the ball grid array device being side as relative position beyond the horizon to the lower surface side, the free end of the contact member imparts lateral downward pressure through Characterized by being in contact from.

  To further illustrate, in the present invention, the socket or mounting housing includes a support member, the top surface of the support member having a plurality of windows for receiving an array of interconnect terminal balls depending from the surface of the ball grid array package. It has been established. The socket also includes a base member to which a plurality of axially extending contact pins or fingers are secured. One end of each finger penetrates the base and serves as an attachment end, and is soldered to a burn-in board or the like. The opposite end of each finger penetrates one of the windows. The central part of each finger (between the free end and the base) passes through a hole in a bending plate attached between the base and the support member. The flexure plate may be fixed or movable laterally with respect to the support member to move the free end of the contact finger relative to the window. The end of each free end is bent so as to deviate from the axis of the finger, and a contact tip is formed at the tip of the free end. The fingers are mounted such that when in the open state, the free ends of the contact fingers are located near one side of each window. When the ball grid array device is placed on the top surface of the support member, the terminal balls protrude or hang down into the window. In the preferred embodiment, a cam is used to move the bending plate laterally, moving the free ends of all contact fingers simultaneously and uniformly in the same direction. For this reason, an edge part is made to contact with a terminal ball | bowl, and a window is closed. The tip of each finger (off the finger axis) is located near the top of the window.

  When the finger is moved by the bending plate, the end comes into contact with the terminal ball above its center line. The fingers are in electrical contact with each ball individually. Since the fingers make contact with the balls above their centerline (between the center of each ball and the surface of the device on which it hangs), the fingers hold the balls in each window and hold the ball grid array device Trap. Since the ball grid array device is held in place by the edge and contacts the ball above the centerline, the ball size can be varied within a certain range without affecting the trapping effect of the contact fingers. Good.

  Due to the simplicity of construction and operation, the ball grid array device mounting apparatus of the present invention can be made from a wide range of materials. Since the top of the socket is open, using an automated process for socket loading and unloading will not damage the device or socket, the top surface of the device may be exposed to a cooling atmosphere, and / or Alternatively, it can be attached to a heat sink. The features and advantages of the present invention will be readily understood from the following detailed description and drawings in conjunction with the appended claims.

  As used herein, the terms "mounting housing" and "socket" are used interchangeably and are devices for receiving a ball grid array in electrical contact with each of the ball grid array terminal balls. Or it is used to represent a mounting device. In the drawings, similar elements are denoted by the same reference numerals.

  The use state of the ball grid array device (10) provided with the mounting housing of the present invention is shown in FIG. The ball grid array device (10) has a bottom surface (11) (see FIG. 3), and a plurality of spherical terminals (12) are formed on the bottom surface. The terminal (12) is formed by piling up solder at a predetermined position on a mounting pad or the like (not shown) on the surface (11) of the device. Various methods for forming such terminal balls are known and do not form part of this invention. By these methods, a substantially spherical body is made (see FIG. 7) and hangs down from the lower surface (11) of the ball grid array device. The terminal ball (12) is usually formed by applying solder and heating, and contracting into a ball shape by surface tension. Regardless of the fabrication method, the spherical terminals protruding from the surface of the ball grid array device shall be referred to as terminal balls or ball terminals.

  The terminal balls (12) are provided in a predetermined grid pattern on the lower surface of the ball grid array device (10). In order to accommodate the ball grid array device, the mounting housing of the present invention uses an upper support member (22) through which a plurality of windows (23) pass. The window (23) is formed in a grid pattern corresponding to the grid pattern of the ball terminals (12). In order to accommodate ball grid array devices of different dimensions, spacers (35) of various sizes are detachably arranged on the upper surface (24) of the support member (22). Spacers (35) define the perimeter of each particular ball grid array device and position the ball grid array device so that the ball grid array device does not move laterally with respect to the top surface (24). Thus, by the spacer (35), each ball grid array can be arranged so that the ball terminal (12) hanging from its lower surface (11) is aligned with the window (23) in position and direction, Also, the size and shape of the ball grid array package can be changed as required.

  In the preferred embodiment shown in FIG. 1, the socket of the present invention is formed from a plurality of plate-like elements (discussed in detail below), which comprise a single box-like housing (100) open at the top and bottom. Is housed inside. As shown in FIGS. 4, 5 and 6, the housing includes a base member (21), and the base member has a plurality of positions substantially coincident with the window (23) of the support member (22). A hole (30) is formed. Each hole (30) has a shoulder (31) inside (see FIG. 6). Each hole (30) is provided with an elongated contact finger (40) as a contact member. In the preferred embodiment, the elongate contact fingers are axially elongate members and are formed from an elastic conductive material, such as, for example, nickel coated steel. The center part (43) of the contact finger (40) has a wide width, and shoulders (45) and (46) are formed at both ends thereof. Therefore, when the contact finger (40) is inserted into the base member (21), the tail (41) passes through the hole (30) and the shoulder (46) is above the shoulder (31). On. A trap plate (25) having a hole (32) and a shoulder (33) corresponding to the hole (30) is fixed to the base member (21) and the shoulder (33). The upper part (44) of each contact finger (40) passes through the hole (32), the shoulder (33) of the hole (32) and the shoulder (45) of the enlarged central part (44) of the contact finger. Contact. Thus, the contact finger (40) is inserted into place in the base member (21) by the trap plate (25) and held firmly.

  The lower end of the contact finger (40) protrudes from the lower surface of the base support (22) and constitutes an input / output end. The tail part (41) may be fixed in a suitable circuit board, burn-in board or the like. Alternatively, other means that can be in electrical contact with the circuit of the support medium may be used.

  The upper part (44) above the central part (43) of the contact finger (40) passes through the hole (54) of the bending plate (28) as a moving member, and its free end (42) is the window part (23 ). In the preferred embodiment, the free end (42) of each finger (40) is sufficiently elongated and constitutes a substantially central axis that penetrates into the window (23) substantially perpendicular to the support surface (24). However, the tip (42a) bends and deviates from the central axis and extends through the window (23) towards the support surface (24) but does not cross the window (23) or surface (24). . In order to obtain the best results, it is desirable that the tip (42a) be as close to the surface (24) as possible without penetrating the surface (24). However, it is only necessary that the tip end portion (42a) exceeds the center line of the contacted ball terminal.

  In the preferred embodiment, each window (23) has a small recess (23a) that houses the end (42) of the contact finger (40). As shown in FIGS. 4, 5 and 6, the bending plate (28) is disposed between the trap plate (25) and the support member (22), but is free to reciprocate laterally with respect to the housing. It is. Since the central part (43) of the contact finger (40) is firmly fixed between the base member (21) and the trap plate (25), the lateral movement of the bending plate (28) causes the contact finger ( The free end (42) of 40) also moves laterally.

  A rotatable cam (50) as a moving member passes horizontally through the mounting housing near one end surface of the bending plate. The cam (50) is attached to one end of the housing (100) by a retainer (53). The opposite end of the cam (50) is controlled by a lever (52). When the lever (52) moves in the first direction, the protrusion (51) of the cam (50) moves and contacts the end surface (29) of the plate (28). In this way, the bending plate (28) moves in the same direction (leftward in FIG. 4) by the rotation of the cam (50) (counterclockwise in FIG. 4). Due to the movement of the bending plate (28), the free end (42) also moves in the same direction, so the free end (42) escapes from the recess (23a) and moves in a direction across the window (23). It will be appreciated that the rotating cam (50) is a desirable means for moving the plate (28). As other means for moving the cam relative to each other, a wedge-shaped member, a ratchet, a plunger, a rack-pinion, or the like can be used. As used herein, the terms “cam” and “cam plate” shall mean any mechanical structure capable of moving the upper part (44) of the contact finger laterally with respect to the support member (22). .

  The position of the upper part (44) of the contact finger (40) when the housing is open is shown in FIG. In this position, the contact finger (40) is relaxed or forced to the open position by a flex plate. If necessary, a spring (not shown) is placed between the housing (100) and the opposite end (29) of the plate (28), with the free end (42) in the recess (23a). You can be sure to get in. Thus, the ball grid array device can be positioned by ball terminals (12) depending in the window (23) simply by placing it in the appropriate position. Since the free end (42) is retracted into the recess (23a), the ball terminal (12) easily enters the window (23). For this reason, no kind of pressure is applied to any part of the ball grid array device (10) or the hanging ball terminal (12). Furthermore, no force (force other than gravity) is applied to any part of the socket from the electronic device package or the ball terminal. When the plate (28) is moved by the protrusion (51) (to the left in FIG. 4), the free end (42) of the contact finger (40) is suspended from the ball terminal (12) in the window (23). Towards the ball terminal, it moves uniformly and simultaneously to contact the ball terminal.

Although best shown in FIG. 2 and illustratively shown in FIG. 7, the free end (42) of the contact finger (40) penetrates into the window (23) near the surface (24). Do not exceed the surface (24). Further, the free end (42) is bent so that the tip (42a) is deflected from the vertical axis of the pin (40) toward the ball terminal (12), and the tip (42a) of the contact finger (40) ) To form a cup or hook. As shown in FIG. 7, the tip end portion (42a) of the free end portion (42) extends beyond the center line of the ball terminal (12). For example, FIG. 7 shows the relative position when the tip (42a) is in contact with the ball terminal when the nominal size of the ball is 0.030 inches. The nominal ball size of 0.030 inches may vary from about 0.035 to about 0.024 inches in diameter. Thus, the ball contacts may vary slightly with variations in ball dimensions. However, as shown in FIG. 7, the free end (42) tip (42a) exceeds the extended center line (horizontal line passing through the center of the ball terminal (12)) by at least 0.001 inch to 0.002 inch or more. The contact of the tip part (42a) of the contact finger (40) is about 5 degrees beyond the extended center line of the ball terminal (12). In this way, since the ball grid array device is trapped and horizontal movement by the spacer (35) is prevented, the pressure acting on the ball terminal (12) by the tip (42a) of the contact finger (40) is lateral. Force component and a small downward force component. The ball grid array device (10) is thus trapped and fixed against the upper surface (24) of the support member (22) by the lateral downward pressure acting on the ball terminal (12) from the contact finger (40). The
It should be noted that the plate (28) is biased to the left in FIG. The tip (42a) of the contact finger (40) moves in the same direction until it contacts the surface of the ball terminal (12). As the bending plate (28) moves further to the left, the central portion (44) of each contact finger (40) bends until approximately 35 grams of contact pressure is applied to each ball terminal. Since the tip (42a) of the contact finger (40) exceeds the center line of each ball terminal (12), this pressure firmly secures the entire ball grid array device near the top surface (24) of the mounting housing. Each contact finger (40) is locked and can be in electrical contact with the ball terminal (12) to test the electrical function and the like. However, a pressure in the range of about 35 grams is insufficient to damage or drop the ball terminal (12).

  After inspection, burn-in or other processes are applied to the ball grid array device (10), simply moving the lever (52) in the opposite direction will release the device and contact finger (40) (if included) Further, the plate (28) is forcibly moved in the opposite direction by a spring), and the tip end portion (42a) enters the recess (23). In the case of the apparatus of the present invention, when the ball grid array device is mounted for performing a burn-in test, the force inserted into the socket is completely zero. The test device need only be placed on the top surface of the mounting housing using gravity. During insertion or removal, no force of any kind acts on the device package or ball terminal (12).

  In the embodiment described above, the bending plate (28) moves laterally by the cam action, and moves the free end (42) of the contact finger (40) to contact the terminal ball (12). However, other configurations can be used to move the terminal ball (12) with respect to the free end (42) of the contact finger.

  In the embodiment shown in FIGS. 8 and 9, the bending plate (28) is maintained in a fixed position, and when the upper support member (22) is moved laterally, the ball terminal (12) is at the same time the free end of the contact finger. In physical contact with the part (42). In this embodiment, the upper portion (44) of each contact finger (40) passes through the hole (54) of the bending plate (28). The hole (54) is positioned with respect to the hole (32) to bias the free end (42) of the contact finger in a direction away from the center of the hole (32). As shown in FIGS. 8 and 9, the contact finger is bent in the opposite direction at the portion passing through the bending plate (28), and the hole (54) of the bending plate (28) has the end portion (42) in the direction of curvature. Is positioned so as to be biased.

  It will be observed that the free end (42) is located in the recess (23a) of the window (23) when the socket is in the open position. However, as described with respect to the embodiment in which the bending plate (28) moves the contact finger by cam action, when the upper support member (22) moves to the right in FIG. 42) is in contact with the free end (42a) at the same time. Those skilled in the art will be able to use other configurations to perform the desired relative movement from the above description.

  When the socket is in the closed position, each of the tips (42a) of the contact fingers (40) has a lateral downward force acting on the ball terminal approximately 5 degrees above its centerline. Since the pressure acting from each finger is limited, there is no possibility of damaging the ball terminal (12). Similarly, when the contact finger (40) is returned to the open position (or the upper plate is moved), the ball grid array device (10) can simply be removed by gravity, or a vacuum pencil, etc. It can also be removed using. It should be noted that the present invention not only nulls the force for insertion and removal, but does not apply any pressure to the ball grid array device other than the terminal balls (12). In fact, since no lid or cover is used, the entire upper surface of the ball grid array device is exposed. Cooling air may be circulated thereon, and a heat sink may be provided. Furthermore, since the test apparatus can be easily loaded by moving vertically using gravity, the test apparatus of the present invention can easily perform loading and unloading by an automated apparatus.

  It should be particularly noted that in all configurations of the present invention, all reactive forces caused by contact between the device and the socket are in the body of the socket housing and are not transmitted to the burn-in board. is there. Opening (or closing) the socket by moving the end (42) of the contact finger relative to the terminal ball (12) requires substantial force. For example, the force required to contact is the force applied from each finger (42) to each terminal ball (12), typically about 1 ounce. For device packages with 1000 or more terminal balls, the total contact force is greater than 62 pounds. This force is a substantial force to be taken into account, because a burn-in board or the like includes a large number of sockets, and each socket is repeatedly loaded and unloaded. However, since the contact fingers are moved simultaneously with respect to the ball terminal by rotation of the cam, all the forces for opening and closing (and the reaction force in the opposite direction) are in the socket. Furthermore, each finger individually contacts only one ball terminal. Thus, only about 1 ounce force acts on one terminal on any terminal. Virtually no force is applied to the device package or support burn-in substrate. Instead, all forces (and reaction forces) acting are in the socket housing.

  It will be appreciated that the materials used to make the mounting housing of the present invention can vary as needed depending on the application. Similarly, the physical size and shape of the elements can be adjusted to accommodate a specific ball grid array device. For example, the illustrated contact finger 40 is an axially elongated metal piece, but can be cut or stamped from a flat ribbon material. However, the fingers (40) may be formed from wire rods and may be formed in various shapes without departing from the principles of the invention. Similarly, if desired, the fingers may be secured in the socket using suitable means. If the socket is used for burn-in, a heat resistant material should be used. In its preferred embodiment, few moving parts are used and it is particularly attractive when used in a hostile environment because the opening and closing function can be easily automated. Thus, the preferred embodiment is very reliable and functional in repeated use.

  As will be appreciated from the foregoing description, the principles of the invention may be employed in a variety of forms to obtain many of the advantages of the disclosed features. Therefore, it should be understood that the disclosure herein is merely exemplary, even though numerous features and advantages of the present invention have been described in conjunction with details of the structure and function of the invention. Various changes and modifications may be made in detail, particularly in size, shape and arrangement of parts, without departing from the scope and spirit of the invention as defined in the claims.

1 is an exploded perspective view showing an assembled state of a preferred embodiment of a ball grid array device having a mounting housing of the present invention. It is a figure which expands and shows a part of upper surface of the attachment housing of FIG. It is a figure which expands and shows a part of ball grid array surface of the ball grid array device of FIG. FIG. 2 is a partial cross-sectional view of the mounting housing device taken along line 2-2 of FIG. 1, showing the position of the contact fingers when the mounting housing is in the open position. FIG. 2 is a partial cross-sectional view of the mounting housing device taken along line 2-2 of FIG. 1, showing the position of the contact fingers when the ball grid array is inserted into the socket and the socket is in the closed position. FIG. 5 is a partial cross-sectional view of the mounting housing of FIG. 1 taken along line 4-4 of FIG. FIG. 4 is an explanatory diagram showing the relationship between the ends of the contact fingers used in the present invention and the terminal balls of balls of various nominal sizes protruding from the surface of the ball grid array device. FIG. 3 is a partial cross-sectional view of another embodiment of the mounting housing device shown in FIG. 1, wherein the flexure plate is maintained in a fixed state and an upper support member is used to move the ball grid array device with respect to the contact fingers. FIG. 9 is a partial cross-sectional view of the device of FIG. 8 showing the relative positions of the contact fingers and the end of the ball grid array device when the socket is in the closed position.

Explanation of symbols

(10) Ball grid array device
(12) Terminal ball
(21) Base member
(22) Support member
(23) Windows
(25) Trap plate
(28) Bending plate
(40) Contact finger
(50) Cam
(100) Housing

Claims (1)

A base member;
From the side to a position where a horizontal line passing through the center of the terminal ball , which is fixed to the base member and has one end in the longitudinal direction and the other is suspended from the bottom surface of the ball grid array device, extends to the bottom surface side. A plurality of elongate contact members having a free end shaped to apply laterally downward pressure by contacting;
A mounting device for a ball grid array device, comprising: a moving member that opens and closes a free end portion of the contact member to move the free end portion of the contact member into and out of contact with a terminal ball of the ball grid array device;
The free end of the contact member is in contact from the side so as to apply a downward pressure in the lateral direction with respect to a position where a horizontal line passing through the center of the terminal ball of the ball grid array device extends to the lower surface side . A ball grid array device mounting apparatus.