KR20030009769A - Test mounting for surface mount device packages - Google Patents

Abstract

The test mounting device for the LGA package of the present invention uses a curved contact finger to make an electrical contact between the lands on the LGA package and a surface mount circuit on the top of the circuit board or the like. The mounting apparatus includes a guide member having a guide hole therein spaced from a support base having corresponding guide holes. The bending plate located between the guide plate and the support base is laterally moved about it to increase or decrease the distance between the ends of each contact finger, so that the circuit is mounted with the LGA package mounted adjacent to the guide plate and the test mounting. The end of the contact finger with the circuit pad on the substrate is connected or not connected.

Description

TEST MOUNTING FOR SURFACE MOUNT DEVICE PACKAGES}

The present invention relates to burn-in and testing of electronic devices in surface mount packages. In particular, it is possible to secure electrical to finely spaced input and output terminal lands or leads on the package without damaging the electronic device, device package, its interconnect terminals or test sockets, and without generating signal distortion. A method and apparatus for mounting and maintaining an electronic device package during burn-in and testing to establish and maintain a connection.

In microelectronics technology, the development trend is to develop electronic device chips and packages that perform more functions faster and take up less space. As a result, the number of electrical interconnections between device packages and external circuits required for circuitry within the chip for communication with the outside world is increasing, and the physical size of each such interconnection must be reduced. In order to provide electrical communication between the chip and external circuitry, the circuit chip is typically contained within a housing or package that supports interconnect pads or lands, leads or balls on one or more interior surfaces.

High pin count devices in a package in which I / O terminals are formed in the form of conductive lands or pads on one or more faces of the package to reduce the overall lead length from the chip to the external circuit and provide adequate spacing between the input and output terminals on the package. High pin count devices are sometimes mounted. The lands are usually opened in parallel and adjacent to the peripheral edge of one face which is in common plane with the surface of the land and arranged parallel to the bottom surface (slightly below) of the package. Parallel rows in which lands cover the entire bottom face in a grid pattern, lands may be grouped adjacent to the center of the bottom face, or arranged in different patterns, such as in various combinations of such arrangements. Such a device package (usually a land grid array or LGA package) is mounted on a circuit pattern on the surface of a circuit board or the like so that the terminal lands are joined to match the lands or pads on the substrate.

In many cases, it is desirable to burn in or test the completed device package before allowing assembly on the circuit board. Terminal lands are mounted directly and permanently on the circuit board by soldering, while establishing and maintaining temporary electrical contacts with each land without damaging or damaging the land, package or encapsulated device chip. It is difficult. For reliable testing and burn-in in such packages, the packages are reusable sockets that precisely interconnect between the input and output lands and external circuits without causing signal distortion problems and without physically damaging the device package, or It should be temporarily mounted on the mounting.

As the size of the package decreases and the number of lands increases, the size and spacing of the lands become smaller. Of course, the smaller and more closely spaced lands, the more difficult it is to contact a test probe or the like. Moreover, for testing when high frequency devices are employed, elongated or lumped contact pins, because the contact pins produce unacceptable signal distortion, especially when finely spaced to contact finely spaced lands. Cannot be used to connect an external circuit to an input / output land.

The conventional burn-in and test apparatus uses a test socket mounted on a burn-in board with a pin-out lead of the test and burn-in socket through the bottom of the socket and through a hole in the circuit board in a conventional through hole mounting. Adopt. Interconnection of high frequency devices with external circuits using such conventional mounting can cause unacceptable signal distortion because the parallel terminal leads through the substrate are high density.

Miniaturized surface mount device packages are currently developed with very finely spaced input and output terminal lands on one face of the package. Such a device package is extremely difficult to handle without damage in shape and physical structure because of its extremely small size, and thus, it is still necessary to make good electrical contact with all the input / output device lands.

Therefore, it is desirable to devise an apparatus that is easy to temporarily mount a small package (preferably automatically) and that is tested or stress tested by burn-in or the like, without causing signal distortion problems or damaging the device package. .

According to one aspect of the present invention, an input and output land on an LGA package is provided by a reusable mounting device that employs a support base and a finger contact pin extending through a guide in the guide plate to engage the guide plate and the input and output lands on the LGA package. Reliable and precise electrical contact is provided between external circuits. The guide plate is formed of an electrically insulating material and has a set of guides (such as holes or channels) arranged to correspond to the terminal land arrangement of the LGA package. The guide plate is supported on and spaced apart from a support base having a set of guides arranged to correspond to input and output lands on an external circuit medium such as a circuit board, burn-in board, or the like. An axially elongated contact pin or finger having first and second ends supported by the shank is such as a substrate such that the first end of the contact finger extends through the guide in the guide plate and the second end of the contact finger burns. It is positioned to extend through the guide in the support base to contact the input and output lands on the external circuit board. The shank of each contact finger extends through a hole in a bending plate located midway between the guide plate and the support base.

When the bending plate is moved in the first direction with respect to the guide plate and the support base, the contact finger is bent to pull the end of the finger toward the bending plate. When moved in the opposite direction, the curvature of the finger is reduced and its end moves outwards through the guides in the guide plate and the support base. As the ends of the fingers move outwards, they engage the guide plates on the circuit board on which the support base is mounted and the terminal lands on the LGA package mounted adjacent to the terminal lands. According to the distance between the land on the LGA and the lands on the fixed circuit board by the size of the mounting apparatus, the contact pressure applied to the contact land is finely controlled by the movement of the bending plate. When the end of the contact finger is expanded and contracted by bending the finger, the ends of the finger move slightly laterally (in a direction opposite to the direction of movement of the bending plate), so that the ends of the finger are very slightly over the surface of the terminal land. Rub, good electrical contact.

One end of each contact finger is supported by the guide plate and the other end is supported by the support base. Each contact finger moves its end only in the axial direction so that it is precisely aligned with the input and output land surfaces on the support substrate and device package under test. Since the ends of the contact fingers are moved only in the axial direction, extremely small diameter contact fingers are used to contact very small and finely spaced terminal lands. Since the contact fingers are very small and relatively short, they have a very small mass. Thus, signal distortions of capacitance induced, inductance induced and impedance induced induced are minimized. In particular, the physical length (lead length) between the input / output land and the external circuit connected by the contact pin is minimized.

The interconnect arrangement of the present invention is used in testing and burn-in of microwave devices in packages that employ very finely spaced terminal lands without causing signal distortion problems. Because of the simplicity of design and operation, the socket device of the present invention is made of various available materials. Since the socket is fed from the top, an automated process can be employed to load / unload the socket without damaging the socket or device package, and the top surface of the device package is exposed for cooling and attachment of the heat sink. .

Further features and advantages of the invention will be readily apparent from the following detailed description taken in conjunction with the appended claims and the accompanying drawings.

1 is an exploded perspective view of an assembly of a land grid array device package according to a preferred embodiment of the mounting apparatus of the present invention;

1A is a partially enlarged view of the top surface of the mounting apparatus of FIG. 1,

FIG. 1B is an enlarged partial view of the land grid array surface of the land grid array device package of FIG. 1;

FIG. 2 is a partial cross-sectional view taken along line 2-2 of the mounting apparatus of FIG. 1 to indicate the position of the contact fingers when the mounting apparatus is in an open state, FIG.

3 is a partial cross-sectional view taken along line 2-2 of the mounting apparatus of FIG. 1 to indicate the position of the contact finger when the land grid array package is inserted into the socket and the socket is in the closed state;

4 is a partial cross-sectional view taken along line 4-4 of the mounting apparatus of FIG.

<Description of the symbols for the main parts of the drawings>

10: LGA Package 12: Terminal Land

13: alignment plate 14: lid

21: guide plate 22, 26: guide hole

23: first page 24: second page

25 support base 27 inner surface

28: outer surface 30: housing

40: finger 41,43: end

42,44: contact end 45: shank

46: tab 50: trap plate

51: hole 60: bending plate

65: Cam 66: Rob

70: substrate 71: pad

The term "LGA package" as used herein includes any package or chip that is encapsulated or not, which package or chip extends in a direction tangential to the plane of the surface of the terminal lands or leads in a direction tangential to the contact pin or finger. It employs a plurality of input and output terminal lands or leads in a plane substantially common with a surface extending in a plane parallel to one face of the chip or package that is in physical contact by the end of the chip. The terms "mounting device" and "socket" are used synonymously to describe a device or device that holds an LGA package while providing electrical communication between an external circuit, such as a circuit board, burn-in boards, and its terminals.

A conventional LGA package 10 having input and output terminal lands 12 arranged in a grid array on the bottom 11 is illustrated in FIG. 1B. The lands 12 are highly conductive metals such as gold lamps which are electrically connected to the circuits inside the package 10 and are soldered to the lands corresponding to the tops of circuit boards employing the conventional surface mount technology and arranged in the resistors. It is arrange | positioned on the surface 11 and upper parts, such as a solder ball. Since various methods are known for forming such terminals, they do not form part of the present invention. Of course, the number and arrangement of lands 12 depends on the size and shape of the package 10 and chips and chips encapsulated therein. As the density of lands 12 on the surface increases, the lands become smaller, and the spacing between lands decreases. Making reliable temporary electrical contact to the surface of finely spaced lands requires very small contact pins that must maintain precise alignment.

The operating arrangement of the LGA package 10 according to a preferred embodiment of the mounting apparatus of the invention is illustrated in FIG. 1. The device package 10 has a bottom surface 11 on which a plurality of terminal lands 12 are formed. The LGA package 10 is positioned parallel to the top surface of the guide plate 21 in the mounting, and the surface of each terminal land 12 is arranged in a register with a hole in the guide plate 21. The adjustable alignment plate 13 is used to align the lands 12 with holes 22 which receive packages 10 of various sizes and shapes. Hinge lid 14 or other conventional closure mechanism is used to secure the LGA package 10 in a fixed state with the top surface of the guide plate 21.

In the illustrated embodiment, the guide plate 21 and the support base 25 are supported in the housing 30 in a fixedly spaced relationship with each other. The guide plate 21 has a plurality of guide holes 22 extending from the first face 23 through the second face 24 serving as a guide for the contact finger 40. The support base 25 has a corresponding guide hole 26 extending from its inner surface 27 to its outer surface 28. The guide plate 21 and the support base 25 are supported in the housing 30 in a parallel state such that the inner surface 27 of the support base 25 is spaced apart from the second surface 24 of the guide plate. The holes 22 in the guide plate 21 and the holes 26 in the support base 25 are aligned in a fixed relationship with each other. In the illustrated embodiment, the holes 22 in the guide plate 21 are directly aligned with the holes 26 in the support base 25. However, direct correspondence alignment is no longer necessary as long as a direct relationship is maintained between each pair of guide holes 22 and 26.

The elongated contact pin or finger 40 is supported in each pair of guide holes 22 and 26 such that an end 41 adjacent to the first contact end 42 is positioned in the guide hole 22 and the second contact end ( An end 43 adjacent 44 is located in the guide hole 26. The first end portion 41 and the second end portion 43 are connected by an elongate center portion or shank 45. A tab 46 (FIG. 4) adjacent to the second end 43 is between the inner surface 27 of the support base 25 and the parallel trap plate 50 spaced apart from the inner surface 27 of the support base 25. Loosely accommodated The trap plate 50 has a guide hole 26 in the support base 25 and a plurality of holes 51 aligned therein.

The hole 51 and the guide hole 26 are formed to dimensions that facilitate the passage of the shank 45 and the second end 43 but do not interfere with the passage of the tab 46. The surface of the trap plate 50 is spaced apart from the inner surface 27 of the support base 25 so as to loosely receive the tabs 46 therebetween. Thus, the axial movement of the contact finger 40 does not allow the first end 41 to be fully retracted from the guide hole 22 in the guide plate 21 and the second end 43 is completely from the guide hole 26. It is limited not to retreat. The ends 41 and 43 are moved axially in the guide holes 22 and 26, respectively, but the axial movement is limited and the dimensions of the guide holes 22 and 26 prevent other movements of the contact finger 40. do.

The bending plate 60 is supported in parallel between the guide plate 21 and the support base 25. The bending plate 60 has holes 61 arranged therein to correspond to the guide holes 22 in the guide plate 21 and the guide holes 26 in the support base 25. The bending plate 60 is positioned such that the shank 45 of each contact finger 40 passes directly through the hole 61. However, the bending plate 60 is mounted for lateral movement in a plane parallel to 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. do.

As shown in FIG. 2, the contact ends 42, 44 of the contact finger 40 allow the lobe 66 to engage the end of the bending plate 60 to move the bending plate laterally (left side in FIG. 2). When the cam 65 is rotated, it is pulled inward (toward the bending plate 60). This curves the finger 40 in a curved manner, thereby reducing the distance between the contact ends 42 and 44, thereby positioning the finger 40 in the "open" position.

The surface mount of the test and burn-in sockets spreads the interconnect circuit across the surface of the substrate and reduces the length of the parallel leads to minimize cross-talk, reactive capacitance, etc. due to signal distortion. Thus, the housing 30 as a mounting device is mounted directly on the surface of a circuit board 70, a burn-in board, etc., having surface mount pads 71 on a surface arranged in a pattern corresponding to the pin-out footprint of the LGA package. do. Thus, mounting 30 provides a direct contact between pad 71 on the substrate and land 12 on the LGA package. Of course, the housing 30 as mounting device is preferably designed to spread the second end 44 to enlarge the pin-out footprint.

With the housing 30 as a mounting device mounted on the substrate 70, the LGA package is mounted on top of the guide plate 21 with the lands 12 aligned in the register with the guide holes 22 in the guide plate 21. It is located adjacent to the face. The lobe 66 is aligned with the contact ends 42 and 44 of the contact finger 40 as the cam 65 is rotated to press the bending plate 50 to the left in FIG. Slightly spaced apart from each of 71. The mounting socket is closed as the cam 65 rotates so that the bending plate 60 moves in the opposite direction (right side in FIG. 3). The bending plate may be moved to the closed position by suitable means such as a spring (not shown) or cam 65.

Depending on the selection of the appropriate material, the finger 40 has enough memory to move the bending plate 60 to the released position (not biased position) upon relinquishing. When the bending plate 60 is moved to the right side of FIG. 3, the contact ends 42 and 44 are moved outwards and guided by the guide holes 22 and 26, respectively, of the land 12 and the pad 71. Engage the sides of.

When the contact ends 42, 44 move outwards, the ends of the fingers 40 are also moved slightly laterally because the curvature of the finger 40 is reduced. The contact ends 42 and 44 thus rub the surface slightly to prevent oxidation and to make good electrical contact with the contact finger 40. Although the bending plate 60 moves all the fingers 40 simultaneously, the pressure applied to each finger is independent of the other fingers. By selecting the composition, size, and shape of the fingers and controlling the movement of the bending plate 60, the pressure applied to the contact ends 42, 44 of each contact finger is precisely controlled.

In a preferred embodiment, the finger 40 is a thin flat ribbon or strip, and the guide holes 22, 26 limit the movement of the contact finger to only axial movements with holes of corresponding shapes and sizes. However, it will be readily appreciated that both the finger 40 and the guide holes 22 and 26 can take other forms as long as the guide holes 22 and 26 control the direction of movement of the end of the finger 40.

Preferably, the bending plate 60 is positioned about halfway between the guide plate 21 and the support base 25 and is laterally moved relative to the guide plate and the support base. However, it will be readily appreciated that other arrangements may produce similar results. For example, either the bending plate 60 and the guide plate 21 or the support base 25 are fixed while the other is moved relative to it. Likewise, the function of the trap plate 50 may be performed by the bending plate 60 if the tabs and the bending plate are positioned approximately the same size.

All parts of the mounting apparatus of the present invention are manufactured from materials available with conventional techniques. Of course, when the mounting device is to be used as a burn-in socket, the material should be selected to be able to withstand repeated use as well as embedded temperature. In addition, it can be seen that the loading and unloading of the device package 10 can be easily automated using conventional techniques.

Likewise, the illustrated embodiment employs alignment plates 13 and lids 14 to orient and hold the LGA package of the type shown in FIG. 1 relative to the guide plate 21, while various forms of construction are terminology. As defined herein, it may be employed to accommodate other types of packages or chips such as bare dies, flip chips and leaded packages configured in the LGA package.

As is apparent from the above description, the principles of the present invention are used to mount to form temporary electrical contact with terminal leads or lands of various device packages without risk of damaging the device or its input / output terminals. Because of its unique structure, the mounting apparatus employing the present invention is used for the burn-in and / or testing of high frequency devices regardless of the signal distortion generated by the test socket or its interconnection with the burn-in substrate or other supporting medium.

Sockets employing the principles of the present invention may be designed and mounted in test and burn-in device packages employing any of a wide variety of input and output terminal arrangements. For example, LGA terminal lands may be arranged in multiple rows, in a centrally concentrated group, or in a full grid array. In addition, the mounting socket can be designed to receive a lead device package, where, from a manufacturing point of view, the lead is of a type having a surface in which the lead is contacted from below (lead package in which the lead is held in the molded carrier ring). Such as

The socket according to the invention can also be designed to contact the underside of the lead extending from a double in-line package, a seagull wing package or other package before (or after) the terminal lead is formed in its final form. The package under test has a plurality of common planar lands or terminal surfaces that are in direct contact from the bottom of the package by vertically extending the ends of the contact fingers that electrically connect the circuits on the outer substrate surface and the terminal lands on the circuit device package. Only thing is needed.

Moreover, the present invention is not limited to mounting only conventional encapsulated device packages. Input and output terminal lands are sometimes formed on bare chip or flip chip devices to form electrical interconnects with other chips or support media in a multi-chip encapsulation package. For example, a plurality of bare chips with terminal lands may be mounted on a single support medium mounted in a single encapsulation package. Sometimes it is desirable to test these chips prior to assembly, so only "Known good die" is finally mounted in the multi-chip arrangement. Such a chip is characterized by having input and output lands on its one face and can be mounted in a test socket employing the principles of the present invention.

Claims (11)

An apparatus for mounting an LGA package having a plurality of terminal lands or leads having a surface extending in a plane parallel to one side of the LGA package, (a) a guide member having a first and a second surface disposed opposite to each other, a plurality of guide holes extending from the first surface to the second surface, the guide members arranged to correspond to the terminal surfaces on the LGA package, (b) a support base having an inner and outer surfaces disposed opposite to each other and a plurality of guide holes extending from the inner surface to the outer surface, the support base being spaced apart from the guide member so that the inner surface is separated from the guide hole in the guide member. A support base spaced in parallel from the second face of the guide member having a guide hole in the support base arranged correspondingly; (c) a bending plate having a hole therein corresponding to the guide hole in the guide member located between the guide member and the support base, the bending plate suitable for lateral movement with respect to at least one of the support base and the guide member; , (d) each having an elongated shank extending between a first free end and a second free end and between the first and second free ends, wherein the portion of the shank adjacent to the first free end is a guide hole in the guide plate. A portion of the shank adjacent to the second free end is located in a guide hole in the support base, the shank having a plurality of axial elongated contact fingers passing through the hole in the bending plate, (e) moving the bending plate laterally relative to the support base and at least one of the guide members to bend each contact finger, thereby increasing the distance between the first and second free ends of each contact finger; And means for reducing. 2. The apparatus of claim 1, further comprising means for limiting axial movement of the contact finger. 2. The apparatus of claim 1, further comprising means for securing an LGA package adjacent to the first surface of the guide member. The method of claim 3, wherein (i) an LGA package secured adjacent to said first surface of said guide member, (ii) further comprising a circuit board having circuit pads on at least one surface secured with contact guides aligned with the guides in the support base adjacent the outer surface of the support base. The device of claim 1 wherein said bending plate moving means is a cam. The apparatus of claim 1 wherein the bending plate and the support base are fixed relative to each other and the guide plate is laterally movable relative thereto. 7. The apparatus of claim 6 wherein the function of the bending plate and the support base is performed by a single structure. 2. The apparatus of claim 1 wherein the bending plate and the guide plate are fixed relative to each other and the support base is laterally movable relative thereto. The method of claim 1, (i) a track plate positioned between the guide member and the support base having a hole therein arranged to correspond to the guide hole in the guide base and the support base; (ii) further comprising tabs on the contact finger located between the trap plate and the support base without passing through a hole in the trap plate. In the mounting device for LGA package, (a) a support base having a plurality of guide holes extending therethrough; (b) a guide plate spaced from the support base and having a guide hole extending therethrough corresponding to the guide hole in the support base; (c) the guide plate and the support with first and second free ends, together with a first free end located in a guide hole in the guide plate and a second free end located in a guide hole in the support base. A plurality of contact fingers suspended between the bases, (d) means for bending the contact finger to increase or decrease the distance between its free ends. In the method for establishing electrical contact between the terminal land on the LGA package and the upper circuit pad such as a circuit board, (a) supporting an LGA package having an input / output terminal land spaced from a circuit board having circuit pads corresponding to the input / output terminal lands on the LGA package; (b) fixing a mounting device between the LGA package and the circuit board, (i) the mounting apparatus comprises a support base having a guide hole therein adjacent to the circuit board having the guide hole aligned with the circuit pad in the register; (ii) a guide plate having therein guide holes arranged in a register together with terminal lands on the LGA package, (iii) the guide plate and the first together with first and second free ends, each with a first free end located in a guide hole in the guide plate and a second free end located in a guide hole in the support base. Having a plurality of contact fingers suspended between the support bases, (c) bending the contact finger in the first direction to reduce the distance between the ends, increasing the distance between the ends to press each end of the contact finger into contact with the input / output terminal lens on the LGA package, each contact And bending the fingers in a second direction to press opposite ends of the fingers to the circuit pads on the circuit board, and alternately performing them.