WO1996034362A1

WO1996034362A1 - Integrated circuit card

Info

Publication number: WO1996034362A1
Application number: PCT/US1996/005626
Authority: WO
Inventors: Steven Feldman; John J. Ashman
Original assignee: Elco Corporation
Priority date: 1995-04-24
Filing date: 1996-04-22
Publication date: 1996-10-31

Abstract

An overmolded or encapsulated integrated circuit card including a circuit board having various components mounted thereon and a connector attached to one end, wherein the circuit board is encapsulated within an encapsulating material to provide substantially solid housing. The molded housing is formed with dimensions which allow the circuit card to mate with electronic components, such as laptop computers. Further, the connector is formed to provide a locking geometry with the housing in order to relieve strain on solder joints connecting the connector to the circuit board.

Description

INTEGRATED CIRCUIT CARD

BACKt ROTJND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to molded or encapsulated objects. More specifically, the present invention is directed to overmolded or encapsulated integrated circuit boards having mounted electronic components and connectors.

For example, PCMCIA cards contain circuit boards having various components mounted t±iereon. The circuit boards may be enclosed in shells to protect the electronic components during use of the cards . The cards also incorporate connection means for connecting the cards to a device, for example a portable computer, and providing access to the circuit board allowing for transfer of information to and from the cards. The connection means may be a simple rectangular part which connects to the circuit board and has sockets located within the rectangular part These sockets are coupled to circuit pathways of the circuit board. Further, the sockets receive pins extending from a port of the portable computer which receives the card. Once the card is plugged into the computer port, the pins should connect to the circuit pathways to allow for the transfer of information. 2. Brief Description of the Prior Arr

Previous cards of this type have oeen pacKaged in various housings. These were typically a shell having some type of frame. The circuit board would be attached to the frame. A top and bottom portion would then be attached to the frame in order to seal the circuit board from the environment.

These housings required a large number of steps in order to complete the assembly. This m turn increased the cost of and time for production. Further, the finished housing was susceptible to warping which would render the card unusable.

Still further, due to the manner of connecting the connection means to the circuit board, typically by solder joints, a great deal of strain is placed on these solder joints during plugging and unplugging of the card and the device.

.ςTTMMARY OF THE INVENTION

The present invention is directed to overcoming the aforementioned drawbacks of the previous housing devices as described above. In one aspect of the present invention, an integrated circuit board is enclosed by encapsulating material which constitutes a housing to provide a f isned card for use with an electronic device Connection means are attached to an end cf the circuit ooard. The housing having encapsulating material s formed to have dimensions which will allow the finished card to cooperate with the electronic device. Another aspect of the present invention provides for locking the connection means to the encapsulating material. The connection means, which is typically attached to the circuit board by solder joints, is shaped such that at least one end there is an interlocking geometry such as a lip or hook. The lip or hook is surrounded oy the encapsulating material during the encapsulating process. Once the material has cured, the lip or hook is encased within the encapsulating material providing a lock between the connection means and the housing. This will serve to relieve some of the strain on the solder joints which attacn the connection means to the circuit board. This result may also be achieved the interlocking of the encapsulating material with solder tails that extend between the connection means and the circuit board. In still another aspect of the present invention, a filler material is added to the circuit board, prior to encapsulating the circuit board, in order to equalize the quantity of encapsulating material molded to each side of the circuit board. Due to a variety of circuit requirements, components are mounted on one or both sides of the circuit board. It is not uncommon to mount different size components or a different number of components on each side of the circuit board. This will result m different total component volume on each side of the circuit board It is also possible that components will be disposed in an asymmetric manner on the two sides of the circuit board and/or the circuit board is located such that its median plane is offset from a corresponding median plane of the housing. Due to the total component volume difference, and/or asymmetric component mounting, and/or offset positioning of the circuit board in the housing, it is possible that the encapsulating material will surround the circuit board unevenly, resulting in a finished card which is warped. The filler material can used to equalize the volume on each side of the circuit board so that during the encapsulation process the encapsulating material is evenly distributed, thereby reducing warp in the finished card.

In another aspect of the present invention, guide rails are attached to the overmolded card. These guide rails reduce the wear and tear on the encapsulating material. Further, the guide rails aid in reducing warp of the finished card. Still further, the guide rails may be used to ground the exterior surface of the card. The guide rails may also reduce the strain on the connection means solder joints during plugging and unplugging. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of an overmolded integrated circuit card of the present invention.

Figure 2 is a top plan view of the overmolded integrated circuit card of Figure 1.

Figure 3 is a sectional view of the overmolded integrated circuit card along line A-A of Figures 1 and 2.

Figure 4 is a partial perspective view of a first embodiment of guide rails for an overmolded integrated circuit card.

Figure 5 is a partial perspective view of a second embodiment of guide rails for an overmolded integrated circuit card. Figure 6 is a partial perspective view of a third embodiment of guide rails for an overmolded integrated circuit card.

Figure 7 is a top plan view of a fourth embodiment of guide rails for an overmolded integrated circuit card.

Figure 8 is a perspective view of the guide rail illustrated in Figure 7.

Figure 9 is a perspective view of a fifth embodiment of guide rails for an overmolded integrated circuit card.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides a circuit card assembly composed of an overmolded or cast housing which encapsulates an integrated circuit board m an encapsulating material providing a substantially solid finished product . Circuit card assemblies according to the invention can be utilized in any manner which is known for circuit cards. To cite several non-limiting examples, such cards could be fully inserted in notebook computers, or inserted into a connector mounted on a circuit board in telecommunications equipment, or installed in an equipment bay or on a card extender external to a cabinet When a card assembly according to the invention is mounted wholly or partly outside of the housing or cabinet of the electronic equipment with which it is associated, tne assembly can be molded to have special snapes tnat perform support or sealing functions, or that provide attachment formations.

Circuit card assemblies according to the invention may have connectors or other types of signal coupling elements, at one or two opposed ends. Typically, a card assembly of the type contemplated by the invention has the form of a rectangle delimited by two sides which extend in a length direction and two ends wnich extend in a width direction. Connectors and/or couplers associated with such a card assembly generally extend along the narrow ends.

Certain embodiments of such card assemblies may be provided with a bus connector at only one end Other embodiments may be provided with a different type of coupler at one end. Still further embodiments may have a bus connector at one end and another type of signal coupling components at the other end. In more general terms, however, a card assembly according to the invention can have any connecting element, cr coupling element, or combination thereof, at any location required by the components with which the card assembly is to interface.

Integrated circuit card assemblies according to the invention could be constructed to have coupling means which need not be mechanically connected to an external system. For example, an integrated circuit card assembly according to the invention could be fabricated to constitute a financial card which would exchange data by means of RF signals. When an individual carrying the card enters his bank, the card could receive a RF signal generated within the Dank and tne card would respond by outputtmg a RF signal identifying the carrier's account number.

Solely for purposes of providing an example and illustrating the present invention only, a PCMCIA card will DΘ described below and illustrated in the accompanying drawings.

The present invention, as illustrated in Figures 1 - 3 , is generally embodied in an overmolded integrated circuit card 1. The card 1 includes a housing 3 of encapsulating material which surrounds and encapsulates an integrated circuit board 2 having various components 4 attached to at least one side; however it is typical to have components 4 attached to both sides of the circuit board 2. The card 1 may further include a bus connector 6 attached to the circuit board 2 at an end 8. The connector 6 s typically attached to the circuit board 2 by solder joints. The connector 6 may include a plurality of soc ets 10 which pass completely or partially through the connector 6 and connect to various circuit patnways 12. The encapsulating material or encapsulant surrounds the circuit board 2 and components 4 and abuts the connector 6. The housing 3 may also have side portions 26, also of encapsulating material. The encapsulating material is preferably a low modulus plastic or similar material . Strictly by way of example, the encapsulating material may DΘ a two part liquid polyurethane system which is used in reaction injection molding. Such a system is marKeted by Miles Laboratories under the tradename Prιsm-200.

In this embodiment the connector 6 is used to connect circuit card 1 to an electronic device, for example a laptop computer As stated above, the connector 6 is a simple connector attached to one end 8 cf the circuit board 2.

A circuit card assembly according to the present invention also incorporates a signal means or interface, such as connector 6 and/or other signal coupling elements as described earlier herein. The signal means or interface allows for signals to be transferred to and from the card 1. In this embodiment, the signal means may be, but are not limited to, the plurality of sockets 10 within the connector 8, which provide signal paths between the electronic device and circuit board 2. The card 1 is constructed to be connected to an electronic device port comprised of a male connector having a plurality of pins extending therefrom. When the connector 6 is mated with the port, each one of the plurality of pins s inserted into one of tne plurality of sockets 10. This allows for the transfer of signals to and from the circuit board 2. The connector 6 is preferably made of a relatively high modulus plastic or a similar material.

In another embodiment, the card 1 may incorporate coupling elements which are encapsulated within the encapsulating material. These coupling elements may be unaffected by, enhanced by or compensate for the electrical or optical properties of the encapsulating material. These properties include dielectric constant and spectral attenuation. These coupling elements can include, but are not limited to, fiber optic terminations under the encapsulating material surface, capacitive coupling where the encapsulating material provides or affects the dielectric constant, inductive coupling for receiving or transmitting oy pickup coil or antenna where the encapsulating material dielectric constant affects circuit resonance, magnetic coupling by use of coils, Hall Effect or otner devices ana a modulated light source at a spectral wavelength wnich is transmitted by the encapsulating material.

As regards possible coupling elements, these include optoelectronic devices, including phototransistors and photodiodes as input devices and LEDs, etc., as output devices. A card assembly according to the invention may be provided with an optoelectronic input device and/or an optoelectronic output device . Optoelectronic devices could suitably be mounted on a top surface of a card assembly according to the invention to facilitate optical, e.g infra-red, communication with ceiling mounted telecommunication nodes. To employ a card m this manner, the card must be given an extended configuration suitable to assure that the housing of the equipment to which the card is connected will not interfere with Ime-of-sight communication between optoelectronic devices on the card and external devices with which optical communication is to be established.

In card assemblies according to the invention, optoelectronic devices can be embedded m encapsulating material and operatively associated w tn optical fibers, light pipes, or other types of light paths, containing mirrors, etc., to place the optoelectronic devices in communication with a region exterior to the encapsulating material. Coupling devices installed in a card assembly according to the invention can further include capacitive or magnetic coupling devices which can produce an exchange of signals between components on a circuit board within the encapsulating material and devices outside of the encapsulating material.

One type of capacitive coupling arrangement that may be used would include an electrode at the surface of the encapsulating material and conductively connected to a conductor on the circuit board, and an electrode located exterior to the encapsulating material and spaced from the first-mentioned electrode by a dielectric layer, which may consist of air. The second electrode would be connected to any desireα external circuit device. In a second capacitive coupling arrangement that may ce used, the first electrode, connected to tne circuit board, would be located beneath the surface of the encapsulating material, so that a certain thickness of encapsulating material is disposed between that electrode and the encapsulating material surface The second electrode would then be mounted directly on the surface of the encapsulating material, so tnat the encapsulating material itself provides the dielectric for the capacitive coupler.

In either case, the second electrode can be supported in the desired position relative to the circuit card assembly by any suitable mechanical holding system.

In the case of magnetic, or inductive, coupling, suitable coils and/or Hall effect transistors can be installed within the encapsulating material to interface with any suitable components located outside of the body of encapsulating material.

Other types of couplers can be conventional transmitters and receivers operating, for example, m the RF band.

The finished card 1 has dimensions X, Y and Z. These dimensions are determined in part by the electronic device with which the card 1 is intended to cooperate. The encapsulating material fills all of the volume within a generally rectangular prism having dimensions X, Y and Z which is not occupied by the circuit board 2, components 4 or connector 6.

Housing 3 of card 1 may have a depression 3 ' molded into a ma n surface thereof to receive a label. Preferably, depression 3' is given a depth (in direction Y) essentially equal to the tnickness of the label, so that when the label is in place tne upper surface of the label is flusn with the portion of the mam surface of housing 3 which surrounds the label. Any surface of housing 3 may be molded to have engraved (recessed) or embossed (raised) logos, identification numbers or other designations, graphics such as insertion arrows, etc.

As illustrated in Figure 3, due to design specifications, it is sometimes necessary to attach components 4 to both sides of the circuit board 2. Whether or not components 4 are mounted on both sides of board 2, the component volume on one side of the circuit board 2 may be greater than the volume on the other side. As a result, the amount of encapsulating material on one side will be greater than on the other side This may cause warping in the finished card 1. In such instances, a filler 16 can be attached to circuit board 2 prior to encapsulation to equalize the volume of encapsulating material on each side of the circuit board 2 m the finished card 1. This will minimize warping of the finished card 1. Filler 16 can be made of any material which is chemically compatible with encapsulating material As filler material, use can be made of sheet plastic which is die stamped to size. Common sheet plastics which may be used include PVC, and polyester materials of the types sold under the tradename Mylar, which would not melt during reaction injection molding and can be readily bonded to circuit boards or circuit devices encapsulated in epoxy materials. Alternatively, any of the engineering thermoplastics, such as polyphenylene sulphide, one example of whicn is sold under the tradename Ryton, could be molded to constitute a filler piece having dimensions specific to the associated circuit board topography. Sucn materials could also be formed into "shims" whicn could be combined to provide a filler of a desired

More generally, filler 16 can be made of any material which can withstand the temperature and pressure of encapsulation, without reacting m an adverse manner with the encapsulating material or with component materials of circuit board 2. Preferably, the filler material is selected to be one which can be adhered in a cost effective manner to a circuit ooard or components thereon. The electrical connection of connector 6 to pathways 12 is effected via solder tails 18. Eacn solder tail 18 has one end connected to a respective socket 10 and its other end connected to a respective pathway 12 by means of a solder joint 19. During plugging and unplugging of the card 1 into a device port, a great deal of strain can occur at these solder joints 19. In the present invention, the connector 6 is formed with ends 20 which provide a lip or hook portion 22. The hook portion 22 delimits an area 24 which receives encapsulating material such that the encapsulating material surrounds the hook portion 22 during the encapsulation process. Thus, hook portion 22 is locked into housing 3. Any connector end 20 which provides for locking the connector 6 to the housing 3 will provide the same result: reduced strain on the connector solder joints 19.

Moreover, when housing 3 is composed of encapsulating material which is molded or cast around circuit board 2, the encapsulating material will surround, and contact, solder tails 18, i.e solder tails 18 will be embedded m the encapsulating material. This secure mechanical connection can be sufficient to reduce strain on joints 19 to safe levels .

In circuit cards according tc the invention, circuit board 2 can be so dimensioned that it is completely surrounded by encapsulating material. Such an embodiment of board 2 is shown in solid lines in Figures 2 and 3. Alternatively, all, or part, of one, two or three sides of board 2 can extend to the edge of housing 3, i.e. can be flush with the outer surface of the encapsulating material which forms housing 3 This latter possibility is shown m broken lines m Figures 2 and 3. In Figure 3, the only observable broken lines illustrate that the edges at three sides of circuit board 2, apart from the portions adjacent connector 6, are flush with the outer surfaces of housing 3.

As illustrated m Figures 1, 3 - 7 and 9 the finished card 1 may include side portions 26 Optionally, side portions 26 can be molded with integral finger grips 27 such as those provided on commercially available PCMCIA cards. According to another possibly, these side portions 26 may receive rails. The guide rails may prevent or correct warp due to uneven volume of encapsulating material on either side of the circuit board 2. Further, the guide rails may prevent wear of low modulus encapsulating material due to extended use. In one emocdiment , illustrated in Figure 4, a pair of grooves 28 s provided longitudinally along the top and bottom cf each side portion 26. Each rail 30 has a corresponding pair of inwardly curved lips 32. Each rail 30 slidably attaches to the respective side portion 26 by longitudinal motion in the direction of arrow A.

In a second embodiment, illustrated m Figure 5, a pair of grooves 34 is provided longitudinally along the top and bottom of each side portion 26. Each rail 36 nas the form of a spring clip with a corresponding pa r of outwardly curved lips 38. Each rail 36 slidably attaches by lateral motion in the direction of arrow B.

In a third embodiment, illustrated in Figure 6, each rail 40 is crimped in place into a side portion 26 by pressing inwardly on the rail 40 in the direction of arrows C after it has been placed around portion 26.

In a fourth embodiment, illustrated m Figures 7

.6 - and 8, the rails 42 incorporate latcnes 44 which connect to connector 6 The connector 6 is formed with a latching detent 46 The side portions 26 provide grooves similar to those illustrated m Figure 4 or Figure 5. When the rail 42 is placed onto side portion 26, the latch 44 settles into place in detent 46 The latch 44 - detent 46 combination cooperates to provide a retaining force against the separation of the connector 6 from the circuit board 2 during removal of the card 1 from an electronic device This retaining force further relieves strain which occurs at the solder joints which connect connector 6 to the integrated circuit board.

In a fifth embodiment, illustrated in Figure 9, the rails 48 and 48' include grounding terminals 50 and 50' . The grounding terminals 50 and 50' penetrate the encapsulant 14 to contact the circuit board 2 or contact the circuit board 2 through molded windows 52 in the encapsulant 14 These ground terminals 50 provide a ground for the conductive exterior surface of the finished card 1. Rail 48 would be installed by sliding that rail along a groove in the outer surface of housing 3, in the same manner as was described above with respect to rail 30 in Figure 4. On the other hand, rail 48' could be installed by pushing rail 48' over one side edge of housing 3 m the direction of arrow B Insertion m this direction would assure that terminal 50 ' enters a suitably located window (not shown) m the side of housing 3 in order to contact the circuit board.

In the case of both rails 50 and 50', terminal 50 or 50 ' can achieve its desired contact by entering into a window formed in housing 3, as mentioned above, or by piercing the encapsulating material of housing 3.

As an alternative to the installation process described above for rail 48' , that rail could be installed cy spreading its side legs apart, m tne manner of rail 40 shown in Figure 6, installing rail 48' so that terminal 50' contacts the circuit board, and then crimping rail 48' in place in the same manner as described above with respect to rail 40 in Figure 6.

The guide rails employed with card assemblies according to the invention, and particularly those having ground terminals, will be made of electrically conductive material, e.g. a copper alloy or stainless steel.

While the exemplary embodiments described above include a mass of encapsulating material which forms a card assembly housing, other embodiments are intended to be within the scope of the invention. For example, a housing of a card assembly according to the invention can be n the form of a shell or case or dielectric material or metal which is molded, cast, drawn, thermoformed or otherwise fabricated in the form of an IC card defining a cavity that will receive a circuit board or electronic circuit m other form

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

Claims

WHAT IS CLAIMED IS:

1 An integrated circuit card assembly comprising: an integrated circuit board including electronic components; coupling means in signal exchange relation with said electronic components for establishing communication between said card assembly on an external device; and a housing encasing the integrated circuit board and components, wherein said housing is constituted by an encapsulating material formed about said integrated circuit board.

2. An integrated circuit card assembly as recited in claim 1, wherein the connection means has at least one end, the end defining an inwardly hooked portion, and wherein the encapsulating material surrounds the hooked portion, locking the connection means to the housing.

3. An integrated circuit card assembly as recited in claim 1, wherein substantially equal amounts of encapsulating material are molded to each side of the integrated circuit board.

4 An integrated circuit card assembly as recited in claim 1, wherein the housing is molded around tne circuit board, and further comprising a filler added to the integrated circuit board to equalize the amount of encapsulating material molded onto each side of the integrated circuit board.

5. An integrated circuit card assembly as recited in claim 1, wherein the housing has two sides in spaced relation to each other, each side having a side portion extending along a side length and further comprising a rail attached to each side portion.