MXPA01007233A - Testing assembly for packages of devices mounted on surfaces. - Google Patents

Abstract

The present invention discloses a testing assembly for LGA packages which employs curved contact fingers to make electrical contact between the supports in the LGA package and the circuit of superficial assembly in a circuit board or similar. The assembly includes a guide member with guide apertures in it, separated from the support base with corresponding guide apertures. A fold plate placed between the guide plate and the support base is laterally moved in relation to them, for increasing or reducing the distance between the ends of each contact finger and in this way connecting or disconnecting the contact fingers ends with the LGA package adjacently assembled to the guide plate and to the circuit board pads in which the testing assembly is mounted.

Description

ASSEMBLY OF TEST FOR PACKAGES OF DEVICES MOUNTED ON SURFACES This invention relates to the burning and testing of electronic devices in surface mounted packages. More particularly, it relates to methods and apparatuses for assembling and holding packages of electronic devices during their burning and testing and to establishing and maintaining positive electrical contact with the inlet / outlet terminals or conductors closely separated in these packages without damaging the electronic device, the device package, its interconnection terminals or the test socket and without introducing signal distortion. Advances in microelectronic technology tend to develop electronic device chips and packages that take up less space while performing more functions faster. As a result, the number of electrical interconnections between the device package and the external circuit required for the circuits in the chips to communicate with the outside world is increased and the physical size of each of the interconnections must decrease. In order to provide electrical communication between the chip and the external circuit, the circuit chips are usually contained in a housing or package that supports interconnect pads or supports, conductors or balls, on one or more of its external surfaces. In order to reduce the total length of the conductor from the chip to the external circuit and to provide adequate space between the input / output terminals in the package, devices of high peak amounts are sometimes mounted in packages in which the Input / output terminals are in the form of conductive supports, or pads formed on one or more sides of the package. The supports are often configured in parallel rows adjacent to the peripheral edges on one of the faces with the surface of the supports in the same plane and parallel with (but a little lower than) the bottom surface of the package. The supports can be accommodated in other formats such as parallel rows that cover the entire lower surface in a grid pattern; the supports grouped near the center of the lower surface; or various combinations of said configurations. These device packages (commonly known as support grid arrangement or LGA packages), therefore, can be mounted on circuit patterns on the surface of a circuit board or the like, such that terminal supports are linked to coupling brackets or pads on the board. In many cases, it is desirable that the entire device package be tested and / or burned before being accepted and assembled on the circuit board. While the terminal supports can be directly and permanently mounted on the surface of the circuit board by welding, it is much more difficult to establish and maintain temporary electrical contact with each support without destroying or damaging the support, package or chip of the encapsulated device. In order to reliably test and burn such packages, the package must be temporarily mounted in a reusable rack or mount, which is precisely interconnected between the input / output supports and the outer circuit without introducing signal distortion problems. and without physically damaging the device package. As the package size is reduced and the number of media is increased, the size and space of the media becomes smaller. Smaller and smaller space supports are, of course, more difficult to contact with test probes or the like. In addition, long or massive contact spikes can not be used to connect the external circuits to the input / output supports to be tested when high frequency devices are involved because such contact spikes, particularly when they are in close quarters in order to make contact with the closely spaced supports, introduce an unacceptable signal distortion. Conventional burn and test devices employ test sockets mounted on a burning board, passing the output peak leads of the test or burning bunker through the bottom of the pool and through the holes in a circuit board in a conventional assembly of holes crossed. The interconnection of high frequency devices with an external circuit using these conventional mounts can induce an unacceptable signal distortion by the high density of the parallel terminal conductors passing through the board. Now packages of miniaturized surface mounted devices having input / output terminal supports are very closely spaced on one side of the package. Such packets of devices, because of their extremely small size, configuration and physical construction, are more difficult to handle without causing damage, and nevertheless a good electrical contact with all the input / output terminal supports is essential. Accordingly, it is desirable to invent devices in which small packages can be assembled temporarily in a simple manner (preferably by automation) and which can be tested and / or tested for burning stress, and the like, without damaging the device package. or without introducing signal distortion problems. In accordance with one aspect of the present invention, a reliable and accurate electrical contact is provided between the input / output supports in the LGA packages and the external circuit by a reusable mounting apparatus employing a support base, a guide plate and finger-shaped contact peaks extending through the guides in the guide plate to engage the input / output supports in an LGA package. The guide plate is formed of an electrically insulating material and has a set of guides (such as holes or channels) configured in correspondence with the configuration of the terminal support of the LGA package. The guide plate is supported and separated from the support base having a set of guides configured in correspondence with the input / output supports in an external circuit means such as a circuit board, a burning board, or the like. An axially elongated peak or finger having first and second ends supported by a rod is positioned such that the first end of the contact finger extends through the guide in the guide plate, and the second end of the finger extends through the guide plate. contact extends through the guide in the support base to make contact with an input / output support on an external circuit board, such as a burning board or the like. The rod of each contact finger extends through an opening in a bending plate placed intermediate the guide plate and the support base. When the bending plate moves in a first direction with respect to the guide plate and the support base, the contact finger is bent, thereby directing the ends of the fingers toward the bending plate. When moving in the opposite direction, the curvature of the fingers is reduced and the ends move outwardly through the guides in the guide plate and the support base. As the ends of the fingers are moved outward, they engage the terminal brackets in an LGA package mounted adjacent to the guide plate and the terminal brackets on a circuit board or the like on which the base is mounted. support. With the space between the brackets in the LGA and the brackets of the circuit board secured by the size of the mounting apparatus, the contact pressure applied to the contact brackets can be tightly controlled by the movement of the bending plate. The extension and retraction of the ends of the contact fingers by folding the fingers, also makes the ends of the fingers fingers move slightly laterally (in the opposite direction to the direction of movement of the fold plate) thereby making the ends of the fingers scrape the surface of the terminal supports very lightly to ensure good electrical contact. One end portion of each contact finger is supported on the guide plate and the other end portion is supported on the support base. Each contact finger is forced in such a way that its ends can only move axially and are precisely aligned with the surfaces of the input / output supports on the support board and the package of the device under test. Because the ends of the contact fingers are forced to move only axially, the contact fingers of an extremely small diameter can be used to contact closely spaced and very small terminal supports. Because the contact fingers are very small and relatively short, they have a very small mass. In this way, the signal distortion induced by the capacitance, induced by the inductance, and induced by the impedance is minimized. More significantly, the physical distance (the length of the conductor) between the input / output support and the external circuit to which it is connected by the contact peak is minimized.

The interconnection configuration of the invention can be used for testing and burning of devices in extremely high frequency packet, using very closely spaced terminal supports without introducing signal distortion problems. Due to the simplicity of design and operation, the inventive basketball devices can be produced from a wide variety of available materials. Because the basketball is loaded from above, automated processes are used to load and unload the basketball without damaging the package of the device or the basketball and exposing the upper surface of the package of the device for cooling and / or for connecting a subsidence of heat. Other features and advantages of the invention will become more readily understood from the following detailed description taken in connection with the appended claims and the accompanying drawings in which: Figure 1 is a perspective view separated into parts of the assembly of a package of the support grid arrangement device, with a preferred embodiment of the assembly of the invention. Figure IA is an exaggerated fragmented view of the upper surface of the assembly apparatus of Figure 1.

Figure IB is an exaggerated fragmented view of the surface of the package grid arrangement of the support grid arrangement device of Figure 1. Figure 2 is a partial sectional view of the assembly apparatus of Figure 1 taken throughout of line 2-2 showing the position of the contact fingers when the assembly apparatus is in the open condition. Figure 3 is a partial sectional view of the assembly of Figure 1 taken along line 2-2 showing the position of the contact fingers when a support grid arrangement package has been inserted into a baseball, and the basketball is in the closed position. Figure 4 is a partial sectional view of the assembly of Figure 1 taken along lines 4-4 of Figure 1. As used herein, the term "LGA package" includes any package or chip, either encapsulated or not, which employs a plurality of substantially coplanar entry / exit terminals supports or conductors with surfaces extended in a plane substantially parallel to one of the faces of the chip or packet that can be physically contacted by the end of one of the contact peaks or fingers extending in a direction substantially normal to the plane of the surface of the terminal supports or conductors, or guides. The terms "mounting apparatus" and "baseball" are used synonymously herein, to describe any device or apparatus for holding such LGA packages while providing electrical communication between their terminals and the external circuit such as a circuit board, burning board , or similar . In Figure IB a conventional LGA package 10 is illustrated having input / output terminal supports 12 configured in a grid arrangement on its lower surface 11. The supports 12 are typically highly conductive metals such as gold or the like, electrically connected to a circuit within the package 10 and configured in the lower surface 11 to be aligned in register with, and welded to, the corresponding supports, solder balls, or the like in a circuit board or the like, employing conventional surface mounting technology. Various methods for forming such terminals are known and do not form part of this invention. The number and configuration of the supports 12 will depend, of course, on the configuration and size of the package 10 and the chip or chips encapsulated therein. As the density of the supports 12 on the surface increases, the supports become smaller and the space between the supports is reduced. Obviously, make a reliable temporary electrical contact with the surfaces of closely spaced supports, requires extremely small contact peaks that have to be maintained with precise alignment. In Figure 1 there is illustrated an operational configuration of the LGA package 10 with the preferred embodiment of the assembly of the invention. The device package 10 has a lower face 11 (see Figure IB) in which a plurality of terminal supports 12 are formed. The LGA package 10 is placed on, or parallel with, the upper face of the guide plate 21 in the assembly 20 and is positioned in such a way that the surface of each terminal support 12 is aligned in register with an opening 22 in the guide plate 21. Adjustable alignment templates 13 can be used to accommodate various sizes and shapes of packages 10 and aligning the supports 12 with the openings 22. An articulated cover 14 or other conventional closing mechanism is used to secure the LGA package 10 in a fixed relationship with the upper surface of the guide plate 21. In the illustrated embodiment, the guide plate 21 and the support base 25 are supported in a housing 30 in a fixedly spaced relationship with one another. The guide plate 21 has a plurality of openings 22 extended therethrough, from its first surface 23 to its second surface 24, which act as guides for the contact fingers 40. The support base 25 has corresponding guides 26 extended through it, from its inner surface 27 to its outer surface 28. The guide plate 21 and the support base 25 are supported in a housing 30 in a parallel relationship spaced apart such that the inner surface 27 of the base 52 is spaced from the second surface 24 of the guide plate. The openings 22 of the guide plate 21, and the openings 26 in the support base 25 are aligned in a fixed relationship with one another. In the illustrated embodiment, the apertures 22 in the guide plate 21 are directly aligned with the apertures 26 in the support base 25. In any case, a corresponding direct alignment is not necessary, as long as a direct relationship between each pair is maintained. guides 22, 26. A contact spike or finger 40 is supported on each pair of guides 22, 26, such that the end portion 41 adjacent the first end 42, is placed on a guide 22, and the end portion 43 adjacent the second end 44 is placed within the corresponding guide 26. The first end portion 41 and the second end portion 43 are connected by an elongated central portion or shank 45. A widened tab 46 (see Figure 4) adjacent to the second portion 43 is comfortably enclosed between the inner surface 27 of the support base 25 and a trap plate 50 which is parallel with, and spaced apart from, the interior surface 27 of the support base 25. The trap plate 50 has a plurality of openings 51 therein aligned with the guides 26 in the support base 25. The openings 51 and the guides 26 are dimensioned in such a way that the rod 45 and the second end portion 43 pass easily through them, but preventing the passage of the tongue 46. The surface of the trap plate 50 is spaced from the inner surface 27 of the support base 25 to comfortably trap the tongue 46 therebetween. Thus, the axial movement of the contact finger 40 is limited such that the first end portion 41 can not be completely removed from the guide 22 in the guide plate 21, and the second end portion 43 can not be completely removed from the guide plate. the guide 26. The end portions 41 and 43 can be moved axially within the guides 22 and 26, respectively, but axial movement is limited and the dimensions of the guides 22, 26 prevent further movement of the contact finger 40. bending plate 60 is supported between and parallel with guide plate 21 and support base 25. Bending plate 60 has a configuration of openings 61 therein, corresponding to the configuration of guides 22 on guide plate 21 and with the guides 26 in the support base 25. The fold plate 60 is positioned in such a way that the rod 45 of each contact finger 40 can pass directly through the opening 61. However, the fold plate 60 is mounted for a lateral movement in a plane parallel with the second surface 24 of the guide plate 21 and the inner surface 27 of the support base 25 in response to the rotation of the cam 65. As shown in Figure 2 the ends 42, 44 of the contact finger 40 are directed inwardly (towards the fold plate 60) when the cam 65 is rotated to engage the lobe 66 with the end of the fold plate 60, and move the fold plate laterally (to the left as shown in Figure 2). This bends the fingers 40 in a curve and reduces the distance between the ends 42, 44 to position the fingers 40 in the "open" position. Surface mounting of test and burnout sockets can minimize signal distortion resulting from interference, reactive capacitance, etc., by extending the interconnection circuit across the board surface, and reducing the driver's length parallel. In accordance with the above, the assembly 30 is mounted directly on the surface of the circuit board 70, the burning board, or the like, which has surface mounted contact pads 71 on its surface configured in the pattern corresponding to the footprint of the output peak of the LGA package. In this way, the assembly 30 provides direct contact between the pads 71 on the board and the supports 12 of the LGA package. It will be appreciated, of course, that the assembly 30 may be designed to extend the second ends 44 in such a way that the footprint of the output peak is enlarged. With the assembly 30 mounted on the board 70, an LGA package is placed adjacent to the upper surface of the guide plate 21 with its supports 12 aligned in registration with the guides 22 on the guide plate 21. With the cam 65 rotated in such a way As the lobe 66 urges the fold plate 60 to the left as shown in Figure 2, the ends 42, 44 of the contact fingers 40 are aligned but slightly spaced from the supports 12 and the pads 71, respectively. The mounting rack is closed by rotating the cam 65 such that the fold plate 60 moves in the opposite direction (to the right as shown in Figure 3). The bending plate can be moved to the closed position by any suitable means, such as by means of springs (not shown) or cams such as cam 65. With the proper selection of materials, the fingers 40 can have sufficient memory to move the plate. fold 60 back to your relaxed position (not forced). As the fold plate 60 moves to the right as shown in Figure 3, the ends 42, 44 move outward and, guided by the guides 22, 26, engage the faces of the supports 12 and the pads 71, respectively. It should be noted that as the ends 42, 44 move outwards, they also move very slightly laterally because the curvature of the fingers 40 is reduced. The ends 42, 44 thus lightly scrape the surfaces with which they are coupled, to remove any rust and ensure good electrical contact with the contact finger 40. Although the fold plate 60 moves all the fingers 40 simultaneously, the pressure exerted by each finger is independent of the other fingers. By selecting the composition, size, and shape of the fingers 40, and controlling the movement of the fold plate 60, the pressure exerted on the contact ends 42, 44 of each contact finger can be controlled precisely. In the preferred embodiment, the fingers 40 are flat and thin strips and the guides 22, 26 are openings of the corresponding shape and size, in such a way that they limit the movement of the contact fingers to a solely axial movement. It will be easily recognized, in any way, that both the fingers 40 and the guides 22, 26 can take on another form, provided that the guides 22, 26 control the direction of movement of the ends of the fingers 40.

Preferably, the fold plate 60 is positioned approximately midway between the guide plate 21 and the support base 25, and moves laterally with respect to the guide plate and the support base. It will be easily recognized, however, that other configurations will produce similar results. For example, the fold plate 60 and either the guide plate 21 or the support base 25 could remain stationary and the other move relative to it. Similarly, the function of the trap plate 50 can be realized by the bending plate 60 if the tabs and the bending plate have adequate size and position. All the components of the assembly apparatus of the invention can be manufactured from easily available materials using conventional techniques. Of course, when the assembly apparatus is to be used as a burnout socket, the materials must be selected in such a way as to withstand the temperatures involved, as well as repeated use. It will also be recognized that the loading and unloading of the device packages 10 can be easily automated using conventional techniques. In the same way, although the illustrated embodiment employs the templates 13 and the cover 14 for orienting and holding an LGA package of the type shown in Figure 1 with respect to the guide plate 21, other different structures can be used to receive other types of packages or chips such as a bare die, blow chips, and packets with conductors configured to be LGA packets as that term is defined herein. It will be apparent, from the above description, that the principles of the invention can be used to assemble and form temporary electrical contact with the conductors or terminal supports of different device packages without risk of damage to the device or its input terminals. departure. Due to the unique structure, the mounting apparatus employed in the invention can be used for burning and / or testing high frequency devices without worrying about the signal distortion introduced by the test stand or its interconnection with the burning board or other means of support. The sockets employing the principles of the invention can be designed and used to assemble, test and burn device packages using any of a wide variety of input / output terminal configurations. LGA terminal stands, for example, can be configured in multiple rows, in centralized groups, or in a complete grid arrangement. Also, the mounting rack can be designed to accommodate packages of devices with conductors wherein the conductors, at some point of their manufacture, have a configuration in which the conductors have a surface that can be contacted from the bottom (such as packages with conductors where the conductors are held in a molded conveyor ring). The sockets according to the present invention can also be designed to contact the bottom of the extended conductors from in-line double packs, single-wing packs, or other different packages, before (or after) the conductors are formed terminals in their final configuration. It is only necessary that the package under test has a plurality of coplanar supports or terminal surfaces that can be contacted directly from below the package by vertically extended contact fingers that electrically connect the circuit of the surface of an external board and the terminal support or conductor of the device package. Moreover, it should be understood that the invention is not limited only to the assembly of packages of conventional encapsulated devices. The input / output terminal supports are sometimes formed into uncovered chips or hit chip devices to form electrical interconnections with other chips or support means in multi-chip encapsulation packages. For example, sometimes a plurality of uncovered chips having terminal supports are mounted on a single support means mounted inside a single encapsulated package. It is often desirable to test these chips before they are assembled, so that only one "good known" die is mounted in the multi-chip configuration. Such chips are characterized by having input / output supports on one of their faces, and can be mounted in test sockets using the principles of the invention.

Claims (11)

1. An apparatus for mounting an LGA package having a plurality of terminal supports or conductors with surfaces extended in a plane substantially parallel to one of the faces of the LGA package, which comprises: (a) a guide member having first and second side facing each other and a plurality of guides extending therethrough from the first face to the second face, and configured in such a way as to correspond to the terminal surfaces in the LGA package; (b) a support base having opposingly arranged internal and external major faces, and a plurality of guides extending therethrough, from the inner face to the outer face supported in a separate relationship with the guide member in such a manner that the inner face is substantially parallel with, and spaced apart from, the second face of the guide member, with the guides in the support base configured to correspond with the guides in the guide member; (c) a bend plate having apertures therein substantially corresponding to the guides in the guide member, positioned between the guide member and the support base and adapted for lateral movement with respect to at least one of the base of support and the guide member; (d) a plurality of axially elongated contact fingers, each having a first free end, a second free end and an elongate rod extended between the first free end and the second free end, with the portion of the rod adjacent to the first free end placed in a guide of the guide plate, the portion of the rod being adjacent the second free end placed in a guide of the support base, and passing the rod through an opening in the folding plate; and (e) elements for moving the fold plate laterally with respect to at least one of the support base and the guide member, to bend each contact finger, and thereby increasing or decreasing the distance between the first free end and the second free end of each of the contact fingers.

2. An apparatus as defined in claim 1, which includes elements for limiting axial movement of the contact fingers.

3. An apparatus as defined in claim 1, which includes elements for securing an LGA package adjacent to the first face of the guide member.

4. An apparatus as defined in claim 3, which includes: (i) an LGA package secured adjacent the first face of the guide member; and (ii) a circuit board with circuit pads on at least one face thereof, and there secured adjacent the outer face of the support base, with the contact pads aligned with the guides in the support base.

5. An apparatus as defined in claim 1, wherein the element for moving the bending plate is a cam. An apparatus as defined in claim 1, wherein the fold plate and the support base are fixed with respect to each other and the guide plate is movable laterally with respect thereto. 7. An apparatus as defined in claim 6, wherein the functions of the bending plate and the support base are performed by the same structure. 8. An apparatus as defined in claim 1, wherein the fold plate and the guide plate are fixed with respect to each other and the support base is laterally movable with respect thereto. An apparatus as defined in claim 1, which includes: (i) a trap plate positioned between the guide member and the support base, having openings therein configured to correspond with the guides in the member of guidance and the support base; and (ii) tabs on the contact fingers placed between the trap plate and the support base, which will not pass through the openings of the trap plate. 10. A mounting apparatus for an LGA package, which comprises: (a) a support base having a plurality of guide openings extended therethrough; (b) a guide plate separated from the support base, and having guide openings extended therethrough, which correspond to the openings of the support base; (c) a plurality of contact fingers having first and second free end portions suspended between the support base and the guide plate, the first portions of free ends being placed in the guide openings of the guide plate, and the second ones being placed free end portions in the guide openings of the support base; and (d) elements for bending the contact fingers, thereby increasing or decreasing the distance between their free ends. 11. The method for establishing electrical contact between the terminal supports in an LGA package and the circuit pads in a circuit board or the like, which comprises the steps of: (a) supporting an LGA package with input terminal brackets / outputs separated from the circuit board, matching the circuit pads with the input / output terminal supports in the LGA package, (b) ensuring a mounting between the LGA package and the circuit board, which has: (i) a support base with guide openings adjacent to the circuit board, the guide openings being aligned in register with the circuit pads; (ii) a guide plate with guide openings aligned in register with the terminal supports in said LGA package; and (iii) contact fingers, each having a first free end portion and a second free end portion, suspended between the guide plate and the support base, with the first free end portion of each of the fingers contact mounted in a movable manner in a guide opening in the guide plate, and the second free end portion of the contact finger movably mounted in a guide opening of the support base; and (c) in an alternative manner, bending the contact fingers in a first direction to decrease the distance between the ends thereof and bending the contact fingers in a second direction to increase the distance between the ends thereof and force at one end of each contact finger for contacting an input / output terminal support in the LGA package, and at the opposite end of each contact finger for contacting a circuit pad in the circuit board.