Mounting electronic components on circuit boards

Abstract: A circuit board has a hole that is large enough to accommodate a portion of an electronic component. Contacts are arranged along a side wall of the accommodated portion of the component. Other contacts are mounted on the board and exposed along the periphery of the hole. The contacts on the component (the first contacts) and the contacts on the board (the second contacts) are arranged to effect electrical contact between the first contacts and the second contacts for a range of positions of the component along a direction perpendicular to the board. A connector for making electrical connection includes a connector body supporting the second contacts in a manner that provides mechanically compliant sliding contact between the first contacts and the second contacts when the component is mounted, and a mechanism that enables the connector to be attached to the board by surface mount soldering.

Description: This invention relates to mounting electronic components on circuit boards. In one approach to mounting an electronic component on a circuit board, shown in United States Patent Application Serial No: 08/552522, filed November 6, 1995, corresponding EP-publication number EP-A-772379, which is considered to represent the closest prior art, the board has a hole that is large enough to accommodate the body of the component. Connection pads located on the surface of the board near the periphery of the hole are soldered to conductors that lie on the body of the component. Because the component lies partly in the hole, the component does not project above or below the hole as it would if it were mounted on the surface of a board that had no hole. The finished circuit board assembly, including the components, may be thinner. In one aspect, this invention provides electrical apparatus comprising: an electrical component having a body, a first portion of the body having a first footprint, and two or more terminals arranged along a side wall of the first portion; a circuit board having a first hole for receiving the first portion of the component body, the circuit board having an interior wall defining the first hole; the apparatus being characterised in further comprising a connector mounted to the circuit board for making contact with the terminals, the connector having a body, two or more contacts, and a mounting mechanism, the two or more contacts having first ends for connection to respective conductive pads on the circuit board and second ends for contact with the terminals, the connector body having an external surface for supporting the side wall of the component, an internal surface for making contact with a wall of the circuit board, and a hidden surface for mating with a surface of the circuit board, and the external surface of the connector body and the interior wall of the circuit board together forming an opening to accommodate the first footprint. In a second and alternative aspect, the invention provides electrical apparatus comprising: a receptacle for mechanically supporting and making electrical connection to a component, the receptacle comprising a circuit board and a connector, and the receptacle having an opening to accommodate a footprint of a first portion of a body of the component; the apparatus being characterised in that the opening has a circumference defined by the circuit board along a first segment and by a connector body along a second segment; and in that the connector has electrical contacts extending into the opening to make contact with terminals on a side wall of the first portion of the component. The embodiment described and illustrated below enables a component to be mounted in any selected position within a range of positions along a direction perpendicular to the board. In the illustrated arrangement, an electronic component is mounted on a circuit board, which has a hole that is large enough to accommodate a portion of the component. Contacts are arranged along a side wall of the accommodated portion of the component. Other contacts are mounted on the board and exposed along the periphery of the hole. The contacts on the component (the first contacts) and the contacts on the board (the second contacts) are arranged to effect electrical contact between the first contacts and the second contacts for a range of positions of the component along a direction perpendicular to the board. Implementations of the invention may include one or more of the following features. A mounting mechanism fixes the component in a selected one of a plurality of the positions. The mounting mechanism includes a portion of the component that is not accommodated by the hole, e.g., a heat sink. The mounting mechanism includes spacers. The second contacts include compliant pins. The first contacts include terminals having surfaces that extend along the direction perpendicular to the board. The second contacts are arranged along two opposite edges of the hole and are soldered to the pads on the board. The pins are compliant in a direction parallel to a surface of the board. The described embodiment employs a connector for making electric connection from the circuit board to first contacts on the component mounted on the board. The connector includes second contacts, a connector body supporting the second contacts in a manner that provides mechanically compliant sliding contact between the first contacts and the second contacts when the component is mounted, and a mechanism that enables the connector to be attached to the board by surface mount soldering. Implementations of the invention may include one or more of the following features. The mechanism includes a solderable clip that engages the connector body and is solderable to a pad on the board. The connector has a wall configured to engage a periphery of a hole in the board that accommodates the component. The second contacts include prongs that are solderable to pads on the board to connect the component to a circuit on the board. The second contacts include pins that are force fitted into holes in the connecter body. The second contacts include compliant fingers that extend away from the connecter body. The extent to which the component projects above or below the board can be easily adjusted. This allows different components having different heights to be accommodated on a common version of a circuit board. It also allows units of a given component to be mounted on different boards at different positions to match the different heights of other components mounted on the respective boards. The connectors can be mounted using the same surface mount soldering steps that are used to solder other surface mounted components to the board. Other advantages and features of the invention will be apparent from the following description, given by way of example: Figure 1 is a perspective view of a power converter and a circuit board. Figure 2 is a perspective view showing exploded connectors. Figure 3 is a cross-sectional view of a connector at 3-3 of figure 1. Figure 4 is an exploded view of a converter and a board. Figure 5 is a side view of a connection between a terminal and a termination finger. Figures 6 through 11 are perspective and side views of three different mounting positions of a power converter on a board. As seen in figure 1, an electronic component 10, such as a power converter, can be mounted at different positions along a direction 12 perpendicular to the plane of a printed circuit board 14 using surface mounted connectors 16, 18. The connectors provide mechanical support for the component and electrical connection between conductive pads 31 (figure 2) on the surface of the board, and terminals 20 on the ends 22 of the component. As seen in figure 2, each of the connectors includes a plastic body 30, a row of conductive terminations 32 that sit within slots 34 provided in the plastic body, and a pair of mechanical retaining clips 36 that are used to surface mount the connector to the board by soldering the clips to the pads 80. In the example shown in figure 1, the body of the converter has a heat-sinking upper portion 42 that has a larger "footprint" than a lower portion 44 which contains the circuitry of the converter. The footprint of the lower portion 44 is roughly matched by a generally rectangular hole 46 in the board 14 so that the lower portion can be accommodated within the hole when the converter is mounted (as seen in figure 6), with appropriate clearance between the periphery of the hole and the outer wall of the converter. Opposite ends of the hole 46 extend beyond the footprint of the converter to accommodate the connectors 16, 18 and have cutouts 50 to accommodate the portions 52 of the connectors 16, 18 that enable them to be mounted to the board using clips 36. Between the two mounting portions 52 of each connector 16, 18, is a termination support section 60 that includes the slots 34 separated by walls 62. The sequence of walls and slots is defined for each connector so that the positions of the terminations 32 match the locations of terminals 20 on the ends of the converter. When a high current terminal of a converter needs to be served, multiple terminations (e.g., a row of closely space terminations 70) can be provided. For example, figure 4 shows a row of closely spaced terminations 70 for use with a wide terminal 21. Thus, any configuration of component terminals and a variety of current carrying needs can be met using a single configuration of terminations 32 and a generally similar connector configuration. To situate each of the connectors securely in the space provided for it at the end of the hole in the board, the connector has a vertical wall 72 with a contour that matches the contour of the peripheral wall of the end of the hole and a horizontal surface 74 that lies against the upper surface of the board. Each mounting portion 52 of each connector has a hole 76 to receive a gripping end 78 of one of the mechanical retaining clips. The other end of the clip has a flat portion 79 that is soldered to a conductive pad 80 on the surface of the board. As seen in figure 3, each of the terminations is stamped from 0.017" (0.04318 cm) thick beryllium-copper sheet and has three "prongs". A middle prong 90 has wavy edges that provide a strong friction fit within a vertical hole 92 in the body of the connector. A surface mount prong 92 extends horizontally and is soldered to a conductive pad 94 on the surface of the board. A third prong 96 serves as a compliant finger (supported at point 98) for contact with a corresponding terminal of the converter. Each connector is assembled by insert stitching each of the terminations into one of the slots of the connector. The assembled connector is placed into the hole in the board. The mechanical retaining clips are mounted on the connector. Using the same surface mount solder process that is used to solder the other surface mounted components, the clips are soldered to their supporting pads and the terminals are soldered to the corresponding conductive pads of the board. As seen in figure 4, the terminals 20 on the ends of the converter are formed from 0.012" (0.03048 cm) thick copper sheet and are bent at a ninety-degree angle. A vertical portion 102 of each terminal lies within a corresponding slot 104 of a plastic terminal support 106. A horizontal portion 108 of each terminal extends along the bottom of the converter and is soldered to a run of a circuit board that extends vertically from inside the main body 110 of the converter in a manner described more completely in United States patent application serial number 08/552,522, filed November 6, 1995, corresponding EP-publication number EP-A-772379. A plastic bottom cap 112 covers the horizontal terminal portions. A heat sink 114 surrounds the body of the converter and provides the larger footprint portion of the converter. The heat sink has four pre-tapped mounting holes 120. Four mounting screws 122 (figure 7) extend from the bottom surface of the board, through clearance holes 128 and into the pre-tapped holes to hold the converter securely in place in a way that permits the converter to be removed easily. As seen in Figure 5, when the converter is mounted in the hole on the board, the finger prong 96 makes contact along the surface of the vertical portion of the converter terminal 20. The vertical portion of the converter terminal is long enough to permit a good contact to be made at a wide range of vertical positions of the converter. In one position, shown in figures 6 and 7, the converter is mounted with the bottom surface of the heat sink in contact with the top surface of the board. The body of the converter then projects more on one side of the board than on the other. In another position, shown in figures 8 and 9, the bottom of surface of the heat sink is spaced from the board by spacers 130. The body of the converter then extends by about equal amounts on opposite sides of the board. In a third configuration, shown in figures 10 and 11, the heat sink is spaced even farther away from the board. During assembly, after the connectors are mounted on the board, any needed spacers are put into place and the converter is slipped into the hole in the board. The terminals on the converter make contact with, and slide along, the fingers of the terminations until the heat sink reaches its final position with the spacers between the heat sink and the board. The screws are then attached. The compliance of the termination fingers enables them to accommodate small variations in the size of the converter body and the configuration of the converter terminals as the converter is being mounted, while still assuring a good electrical connection. Variations from the embodiment particularly described above can of course be made within the scope of the invention. For example, the component need not be a power converter. The hole may have a wide variety of shapes and the number, shape, and locations of the connectors can vary widely. The terminations and terminals could be transposed so that the component bears the compliant fingers and the connectors bear the relatively long vertical terminal portions.

Claims: Electrical apparatus comprising: an electrical component (10) having a body, a first portion (44) of the body having a first footprint, and two or more terminals (20) arranged along a side wall (22) of the first portion; a circuit board (14) having a first hole (46) for receiving the first portion of the component body, the circuit board having an interior wall defining the first hole; the apparatus being characterised in further comprising a connector (16, 18) mounted to the circuit board for making contact with the terminals, the connector having a body (30), two or more contacts (32), and a mounting mechanism, the two or more contacts having first ends (92) for connection to respective conductive pads (31) on the circuit board and second ends (96) for contact with the terminals, the connector body having an external surface for supporting the side wall of the component, an internal surface for making contact with a wall of the circuit board, and a hidden surface (74) for mating with a surface of the circuit board, and the external surface of the connector body and the interior wall of the circuit board together forming an opening to accommodate the first footprint. Apparatus according to Claim 1, further characterised in that the connector supports the side wall and makes electrical contact with the terminals over a range of positions of the component relative to the board in a direction perpendicular to the board. Apparatus according to Claim 2, characterised in further comprising a component mounting mechanism (122, 128, 130) that fixes the component in a selected one of the positions. Apparatus according to Claim 3, further characterised in that the component mounting mechanism includes a second portion of the body, preferably comprising a heat sink (114), protruding beyond the footprint. Apparatus according to Claim 4, further characterised in that the component mounting mechanism comprises spacers (130). Apparatus according to Claim 1, further characterised in that the first ends (92) of the contacts are soldered to respective pads (94) on the circuit board. Apparatus according to Claim 1, further characterised in that the two or more terminals span a portion of the side wall in a direction perpendicular to the circuit board. Apparatus according to Claim 1, further characterised in that the mounting mechanism of the connector further comprises a mounting clip (36) having an end (79) for soldering to the circuit board and another end (78) for securing the connector body. Apparatus according to Claim 1, further characterised in that the contacts are arranged along two opposite edges of the hole. Apparatus according to Claim 9, further characterised in that the contacts along the opposite edges of the hole are spaced to provide a pressure fit against the terminals with the first portion in the opening. Apparatus according to Claim 9, further characterised in that the connector body comprises a first connector segment (16) and a second connector segment (18) respectively comprising first and second interior walls, and the opening is formed by the first and second interior walls separated along a circumference of the opening by the exterior wall. Electrical apparatus comprising: a receptacle (14, 16, 18) for mechanically supporting and making electrical connection to a component (10), the receptacle comprising a circuit board (14) and a connector (16, 18), and the receptacle having an opening (46) to accommodate a footprint of a first portion (44) of a body of the component; the apparatus being characterised in that the opening has a circumference defined by the circuit board along a first segment and by a connector body along a second segment, and in that the connector has electrical contacts (96) extending into the opening to make contact with terminals (20) on a side wall of the first portion of the component. Apparatus according to Claim 12, further characterised in that the connector comprises a first connector (16) and a second connector (18) mounted to the circuit board on opposite sides of the opening. Apparatus according to Claim 13, further characterised in that the first and second connectors are spaced so that the electrical contacts provide a pressure fit with the first portion of the component in the opening. Apparatus according to Claim 12, further characterised in that the connector body comprises a first connector body (16) and a second connector body (18), and in that the second segment is divided into at least two portions by the first segment. Apparatus according to Claim 12, characterised in further comprising a hole in the circuit board comprising a first hole segment and a second hole segment (50), the first hole segment defining the opening along the first segment, and the second hole segment being larger than the opening along the second segment. Apparatus according to Claim 16, further characterised in that the connector body lies in the second hole segment. Apparatus according to Claim 17, further characterised in that the second hole segment has a contour to match an edge of the connector body. Apparatus according to Claim 12, further characterised in that the contacts (32) are soldered to respective pads (94) on the circuit board. Apparatus according to Claim 12, further characterised in that the contacts comprise a cantilever having a first end (96) for contacting the terminals, a second end (92) soldered to the board and a prong (90) secured to the connector body. Apparatus according to Claim 20, further characterised in that the contacts are stamped from beryllium copper. Apparatus according to any preceding claim, further characterised in that a plurality (70) of the contacts are connected in parallel to contact a single terminal (21). Apparatus according to Claim 22, further characterised in that the plurality of the contacts are spaced closer together than others of the contacts. Apparatus according to any preceding claim, further characterised in that the connector body further comprises slots (34) separated by walls (62) and the contacts are in the slots. Electrical apparatus comprising an apparatus according to Claim 12 with the said component (10) mounted with the first portion (44) in the opening (46). Apparatus according to Claims 1 or 25, further characterised in that the component comprises a power converter. Apparatus according to Claims 1 or 25, further characterised in that the terminals (102) are positioned in slots (104) in the side wall extending in a direction perpendicular to the board. Apparatus according to Claim 28, further characterised in that the terminals have a length along the perpendicular direction sufficient to provide a range of positions for the component relative to the board along the perpendicular direction in the opening. Apparatus according to Claim 12, characterised in further comprising a component mounting mechanism (122, 128, 130). Apparatus according to Claims 3 or 29, further characterised in that the component mounting mechanism is separate from the connector. Apparatus according to any preceding claim, further characterised in that the connector is surface mount soldered to the board. Apparatus according to any preceding claim, further characterised in that the contacts further comprise compliant pins (96). Apparatus according to Claim 32, further characterised in that the pins are compliant in a direction parallel to the surface of the board. Apparatus according to any of Claims 1 to 31, further characterised in that the contacts further comprise a prong (90) and the connector body comprises a receptacle (92) for the prong. Apparatus according to Claim 34, further characterised in that the prong is force fitted into the receptacle. Apparatus according to any preceding claim, further characterised in that the opening further comprises a shape to match the footprint.

Inventors: KEAY GARY, VINCIARELLI PATRIZIO, KEAY, GARY, VINCIARELLI, PATRIZIO
Applicants: VLT CORP, VLT CORPORATION
Application year: 2000
Main classification: H01R12
IPC codes: H01R33, H05K1, H01R12, H01R29, H05K13