United States Patent [191
`Flynn et a1.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,921,160
`May 1, 1990
`
`4,843,225 6/1989 Hoppe ............................... .. 235/492
`4,849,617 7/1989 Ueda ................................. .. 235/492
`FOREIGN PATENT DOCUMENTS
`France .
`58-210646 12/1983 Japan .
`
`61-14-5696 7/1986 Japan .
`Primary Examiner-David L. Trafton
`Attorney, Agent, or Firm-Robert B. Levy
`[57]
`ABSTRACI
`A personal data card (10), comprised of a semiconduc
`tor chip (28), sealed by encapsulant (38) m an opening
`(26) in a body (12), is advantageously provided with a
`shock absorbing device (38) which suglsitantiallly cir
`cumscribes the encapsulant to substanti y iso ate the
`encapsulant from the body of the card. By isolating the
`encapsulant from the card body, the shock absorbing
`device reduces the stresses transmitted from the card
`body into the capsulant and into the chip when the card
`is ?exed. In this way the incidence of cracking of the
`chip caused by the stresses generated upon ?exing of -
`the card is reduced.
`
`11 Claims, 2 Drawing Sheets
`
`[54] PERSONAL DATA CARD AND METHOD OF
`CONSTRUCI‘ING THE SAME
`[75] Inventors: Richard M. Flynn, Indianapolis, Ind.;
`Fred W- Verdi, Lawrenceville, NJ.
`-
`
`.
`
`-
`
`[73] Asslgnee' $333; 11;?:?l$::ku§_&legmph
`_
`[21] Appl' No" “L515
`[22] Filed:
`Feb. 29, 1988
`(as """""""""""""""
`[58] Fi'elh
`' ' ' ' ' '
`' ' ' ' "
`c .............................. ..
`References Cited
`Us‘ PATENT DOCUMENTS
`3,637,994 1/1972 Ellingboe ....................... .. 235/6112
`4,222,516 9/1980
`4’4l7’413 11/ ‘983
`
`0
`
`[56]
`
`2359488 492
`,
`
`4’692’604 9/1987
`4:737:62O 4/1938
`4,746,392 5/1988
`4,764,803 8/1988
`
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`US. Patent ’May 1,1990
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`Sheet 1 012
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`4,921,160
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`FIG. 1
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`FIG.
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`Patent‘
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`May 1, 1990
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`Sheet 2 of 2
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`FIG. 3
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`w mwm
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`.50
`RELATIVE BEND DIAMETER
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`1
`
`METHOD OF
`PERSONAL DATA CARD
`CONSTRUCI'ING THE SAME
`
`TECHNICAL FIELD
`This invention relates to a personal data card contain
`ing an electronic circuit comprised of one or more inte
`grated circuit chips, and to a method of manufacturing
`such a card.
`
`10
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`4,921,160
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`ient, shock-absorbing device, comprised of a ring or a
`plurality of ring segments of an elastomer (e.g silicone
`rubber) of a height at least as high as the chip, is con
`tained in the card body, substantially coplanar with the
`chip, to substantially circumscribe the mass of encapsu
`lant. The shock-absorbing device thus serves to substan
`tially separate the encapsulant and the chip contained
`therein from the bulk of the card body. A cover overlies
`the recess in the card body. Upon ?exing of the personal
`data card, lateral stresses which would otherwise be
`transmitted through the card body and into the encap
`sulant, and hence, the chip, are substantially absorbed
`by the resilient shock-absorbing device, thereby reduc
`ing the incidence of chip cracking which causes failure
`of the card.
`
`BACKGROUND ART
`Presently, a number of electronics manufacturers are
`engaged in developing a personal data card which ap
`pears similar to a conventional plastic credit card, but
`additionally contains an electronic circuit, typically
`comprised of a memory and a microprocessor. The
`electronic circuit carried by the personal data card
`enables the card to store large amounts of information,
`far more than a conventional plastic credit card. Infor
`mation carried by the card may be accessed and even
`altered once the card is inserted into a card reader
`adapted for this purpose. The ability of the personal
`data card to store large amounts of information makes it
`useful for many applications. For example, a personal
`data card could be used as a telephone credit card or a
`credit card.
`An example of a personal data card is disclosed in I
`US. Pat. No. 4,649,418, issued on Mar. 10, 1987, to E.
`Uden. The Uden personal data card is comprised of a
`PVC card body having at least one aperture sized to
`receive a carrier body which takes the form of an epoxy
`glass circuit board. Within the carrier body is a through
`hole, sized to accommodate a semiconductor chip
`which has a set of pads thereon, each coupled by a wire
`lead to a corresponding metallized area'on the carrier
`35
`body adjacent to the through hole. A frame, formed of
`fiber-reinforced epoxy resin, is placed on the carrier
`body about the through hole to serve as a dam to con
`tain epoxy encapsulant admitted into the through hole
`in the carrier body to seal the chip therein. Each of a
`pair of cover plates is attached to opposite sides of the
`card body to seal the carrier body within the aperture in
`the card body.
`The Uden personal data card is believed to suffer
`from the disadvantage that stresses applied to the card
`during ?exing are likely to be transmitted through the
`card body and into the encapsulant and semiconductor
`chip, possibly causing chip cracking which will render
`the card inoperative. The incidence of chip cracking
`can be lessened by employing semiconductor chips
`which occupy a small surface area, typically less than 25
`square millimeters. However, the amount of data that
`can be stored in a memory chip decreases when the size
`of the chip is decreased. Thus, restricting the size of the
`chip below 25 square millimeters restricts the amount of
`data that can be stored on the card.
`Therefore, there is a need for a personal data card
`which exhibits reduced incidence of chip cracking with
`out restricting the chip size.
`
`BRIEF SUMMARY OF THE DRAWINGS
`FIG. 1 is a partially cut away, perspective view of a
`personal data card, which includes a resilient shock
`absorbing device in accordance with the present inven
`tion;
`FIG. 2 is a cross-sectional side view of the personal
`data card of FIG. 1;
`FIG. 3 is a graphical plot of the percentage failure
`versus relative bending diameter for personal data cards
`which include the shock-absorbing device of the pres
`ent invention and for those personal data cards which
`do not; and
`FIG. 4 is a partial perspective view of a portion of the I
`data card of FIG. 1, showing an alternate embodiment
`of the shock-absorbing device.
`DETAILED DESCRIPTION
`FIGS. 1 and 2 show a partially cut away, perspective
`view, and a cross-sectional side view, respectively, of a
`preferred embodiment of a personal data card 10 con
`structed in accordance with the present invention. The
`card 10 includes a card body 12 comprised of a circuit
`board 14 having ?rst and second major surfaces 16 and
`18, respectively. The card body 12 also includes a struc
`tural member 20 bonded onto the surface 16 of the
`circuit board 14 by a layer of adhesive 22. Both the
`circuit board 14 and the structural member 20 are fabri
`cated from a very high modulus material, such as FR-4
`or epoxy resin, for example. The circuit board 14 has a
`plurality of selectively interconnected metallized areas
`24, typically gold or copper, formed on its surface 16.
`The structural member 20 has one or more apertures 26
`typically circular in shape, extending therethrough for
`exposing selected groups of the metallized areas 24 on
`the surface 16 of the circuit board 14.
`At least one semiconductor chip 28, typically a mem
`ory chip or the combination of a memory and micro
`processor chip, has its undersurface secured to one or
`more of the metallized areas 24 which are exposed
`through the aperture 26. The chip 28 has a plurality of
`conductive pads 30, usually on its top, which are each
`selectively coupled by a separate one of a set of small
`diameter wires 32 to a separate one of the metallized
`pads 24 on the surface 16. Each wire 32 typically has a
`small loop 34 near the end thereof connected to the pad
`30 on the chip 28 to afford the wire a small degree of
`strain relief. The loop 32 is sized so as to lie below the
`top of the structural member 20. It should be noted that
`the wires 32 are not the only mechanism by which the
`chip 28 can be electrically connected to the circuit
`board 14. Other well-known techniques, such as tab
`
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`30
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`50
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`55
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`BRIEF SUMMARY OF THE INVENTION
`Brie?y, a personal data card, which substantially
`overcomes the aforementioned disadvantage, is com
`prised of a card body which mounts at least one semi
`conductor chip. Typically, the chip is mounted within a
`recess in the card body so as to be supported by the
`bottom wall of the recess. A quantity of encapsulant is
`admitted into the recess to seal the chip therein. A resil
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`bonding and ?ip-chip bonding, could also be employed
`the discrete components, like the chip 28, will be sub
`to electrically connect the chip 28 to the metallized
`jected to much less stress upon ?exing of the card 10.
`areas 24.
`As described above, the shock-absorbing device 38 is
`Once the chip 28 has been electrically connected to
`typically fabricated of a solid silicone or latex rubber
`the metallized areas 24 via the wires 34, then a quantity 5
`ring which is pressed into the opening 26 in the struc
`of encapsulant 36 is admitted into the opening 26 to seal
`tural member 20. Alternatively, the shock-absorbing
`the chip therein. The encapsulant 36, which is ty'pically
`member 38 could be formed of a highly viscous liquid
`a silica-?lled epoxy resin, is initially viscous when ad
`elastomer precursor (not shown) directly extruded into
`mitted into the opening 26 but later cures into a hard,
`the opening 26 prior to the admission of the encapsulant
`solid mass having a modulus on the order of the circuit
`36 therein. After being extruded into the opening 26, the
`board 14 and the structural member 20. Thus, the en
`liquid elastomer precursor is cured to provide a resilient
`capsulant 36 will, when cured, provide a hard, protec
`ring-like structure which runs along the inside wall of
`tive shell about the chip 28.
`the opening to circumscribe the chip 28. Finally, the
`In a preferred embodiment of the personal data card
`encapsulant 36 is admitted into the opening 26 as before.
`10, the chip 28 is chosen to provide the card with a large
`A cover 40, typically comprised of a layer 42 of
`memory capacity. As a consequence, the chip 28 tends
`epoxy resin impregnated with glass ?ber so as to have a
`to occupy a large area (>25 square millimeters) on the
`very high modulus, is bonded to the top surface of the
`surface 16 of the circuit board 14. In the past, the use of
`structural member 20 to seal the recess 26 and thus
`such a large chip would have been avoided because of
`overly the chip 28. Once the layer 42 is bonded onto the
`the increased incidence of chip cracking upon ?exing of 20
`structural member 20, the shock-absorbing device 38
`the card 10.
`will be interposed between the layer and the circuit
`To overcome this problem, the personal data card 10
`board 14. In addition to theepoxy layer 42, the cover 40
`advantageously includes a shock-absorbing device 38
`also may include a label 44 bonded to the top of the
`for reducing the stresses transmitted through the struc
`epoxy layer. The label 44 contains indicia (not shown)
`tural member 20 into the encapsulant 36 and the chip 28
`which serve to identify one of the pair of major surfaces
`upon ?exing of the card. As best seen in FIG. 1, the
`of the card 10. Another indicia-bearing label 46, of the
`shock-absorbing device 38 takes the form of a solid
`same thickness as the label 46, may be applied to the
`reslient ring, fabricated from an elastomer (e.g., silicone
`surface 18 of the circuit board 14 for identifying the
`or latex rubber). The device 38 is sized to ?t snugly
`other major surface of the card 10.
`within the opening 26 against the side walls thereof so 30
`In order to verify the ef?cacy of the shock-absorbing
`as to be substantially coplanar with the chip 28 and
`device 38, a quantity of the personal data cards 10 were
`substantialy flush with the top of the structural member
`bent over a plurality of cylinders (not shown) of succes
`20. During manufacture of the card 10, the shock
`sively smaller diameters in order to apply successively
`absorbing device 38 is placed inside the opening 26
`greater lateral stresses to the cards. Similarly, a quantity
`prior to the admission of the encapsulant 36. In this
`of control cards, each identical to the card 10 but lack
`way, the shock-absorbing member 26 will circumscribe
`ing the shock-absorbing device 38, were also succes
`the encapsulant 36 once it has been admitted into the
`sively stressed in the same manner. In FIG. 3 there is
`opening, thereby substantially isolating the encapsulant
`shown a plot of the percentage failure versus the rela
`and the chip 28 therein from the structural member 20.
`tive bend diameter (de?ned by the ratio of the largest or
`The resilient nature of the shock-absorbing device 38
`beginning cylinder diameter to the test cylinder diame
`affords it a much lower modulus than either the encap
`ter) for the cards with and without the shock-absorbing
`sulant 36 or the structural member 20. Since the shock
`device 38. Card failure was deemed to have occurred
`absorbing device 38 has a much lower modulus, the
`when the circuitry on the card failed to operate prop
`device is able to absorb a large portion of the lateral
`erly, usually ‘due to cracking of the semiconductor chip
`stresses transmitted into it from the structural member
`
`452 8
`20 when the card 10 is ?exed. As a result, the stresses
`The dashed line in FIG. 3 represents the percentage
`passing into the encapsulant 38, and hence, into the chip
`failure as a function of bend diameter for those personal
`28 from the structural member 20 are signi?cantly re
`data cards lacking the shock-absorbing device 38. As
`duced, thereby reducing the incidence of cracking of
`can be seen in FIG. 3, those cards lacking the shock
`the chip.
`’
`absorbing device 38 of FIGS. 1 and 2 began to fail when
`50
`In addition to the chip 28, one or more discrete de
`the relative bend diameter ratio fell below 0.83. Nearly
`vices (not shown) may be mounted to selected metal
`50% of those cards lacking the shock-absorbing device
`lized areas 24 on the surface 16 which are exposed
`38 failed after the relative bend diameter ratio fell below
`through one or more additional openings (not shown) in
`0.58.
`the structural member 20. Like the chip 28, these dis
`The solid line in FIG. 3 represents the plot of the
`crete components are typically sealed within the struc
`percentage failure versus bend diameter for the card 10
`tural member 20 by way of an encapsulant (not shown)
`of FIGS. 1 and 2 whose semiconductor chip 28 was
`similar to the encapsulant 38. In order to reduce the
`circumscribed by the shock-absorbing device 38. As
`stress on the discrete components created by flexing of
`may be appreciated, few if any of the cards 10 which
`the card 10, it may be useful to place a shock-absorbing
`included the shock-absorbing device 36 failed until the
`device, similar to the device 38, within each opening in
`relative bend diameter ratio had fallen to below 0.50.
`the structural member 20 containing the discrete com
`Thus, it can be concluded that the shock-absorbing
`ponents prior to the admission of the encapsulant
`device 38 does signi?cantly reduce the amount of
`therein. In this way, the encapsulant surrounding each
`stresses transmitted to the semiconductor chip 28 dur
`of the discrete components will be circumscribed by the
`ing ?exing of the card 10.
`shock-absorbing device. By circumscribing the encap
`Referring now to FIG. 4, the shock-absorbing device
`sulant surrounding each of the discrete components
`38, instead of being con?gured of a solid ring, as shown
`with a shock-absorbing device similar to the device 38,
`in FIGS. 1 and 2, may be formed of a plurality of ring
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`shock absorbing means are provided to substantially
`segments 50 which are embedded within the structural
`circumscribe both the encapsulant and the semi
`member 20 proximate the aperture 26 so as to substan
`conductor chip sealed therein and thereby substan
`tially circumscribe the circumference thereof, and
`tially isolate the encapsulant and the chip from the
`hence the mass of encapsulant 36 (see FIGS. v1 and 2).
`body to reduce the stresses transmitted from the
`The ring segments 50 comprising the shock-absorbing
`body into the encapsulant upon ?exing of the sub
`device 38 of FIG. 4 are embedded in the structural
`strate.
`member 20 by ?rst overlying the member with a sheet
`2. The card according to claim 1, characterized in
`of elastomer 52. A punch 54, con?gured with a set of
`that the shock absorbing means comprises an elasto
`cutting surfaces 56, each shaped in the form of ring
`meric ring located along the inside periphery of the
`segments spaced about a central axis, is driven through
`opening in the body.
`the sheet 52 and into the structural member 20 so that
`3. The card according to claim 1, characterized in
`the ring segments 50 are punched out from the sheet and
`that the shock absorbing means comprises a plurality of
`embedded into the structural member about the opening
`elastomeric ring segments embedded within the body
`26 therein in a single operation. It should be understood
`proximate the opening therein to substantially circum
`that ring segments 50, when embedded in the structural
`scribe the periphery thereof.
`member 20 about the aperture 26, will be substantially
`4. The card according to claim 2, characterized in
`coplanar with the chip 28 and will serve to substantially
`that said elastomeric ring is fabricated from a latex rub-.
`isolate the encapsulant 38 (see FIGS. 1 and 2) within the
`her.
`aperture 26 from the bulk of the structural member.
`5. The card according to claim 2, characterized in
`Thus, the ring segments 50 comprising the shock
`that said elastomeric ring is fabricated from silicone
`absorbing device 38 of FIG. 3 provide a similar degree
`rubber.
`of stress relief to the chip 28 (see FIGS. 1 and 2), as does
`6. The card according to claim 3, characterized in
`the solid ring-type shock-absorbing device 38 of FIGS.
`that said elastomeric ring is fabricated from a latex rub
`1 and 2.
`bet.
`The advantage obtained by con?guring the shock
`7. The card according to claim 3, characterized in
`absorbing device 38 as a plurality of ring segments
`that said elastomeric ring is fabricated from silicone
`rather than a solid ring is that manufacturing of the card
`rubber.
`8. A method for making a personal data card compris
`10 is greatly facilitated. When the shock-absorbing de
`ing the steps of:
`vice 38 is con?gured of a solid ring, as shown as in
`placing at least one semiconductor chip into at least
`FIGS. 1 and 2, extreme care must be taken to size the
`one opening in a body;
`ring properly; otherwise, if the ring is too large, inser
`admitting encapsulant into the opening in the body to
`tion thereof into the aperture 26 becomes extremely
`seal the chip; and
`difficult. Conversely, if the solid ring-type shock
`bonding a cover to said substrate to overly the open
`absorbing device 38 of FIGS. 1 and 2 is signi?cantly
`ing therein, characterized in that:
`undersized, it can fall out of the aperture 26 in the struc
`the chip has one of its surfaces bonded to the body;
`tural member 20 if the card 10 is tilted during assembly.
`and
`These probleYns are avoided by con?guring the shock
`shock-absorbing means are placed in the body prior
`absorbing member 38 as a plurality of ring segments 50
`to the admission of the encapsulant so as to substan
`which are embedded directly in the structural member
`tially circumscribe the encapsulant and chip and
`28 about the periphery of the aperture 26.
`thereby substantially isolate both the encapsulant
`It is to be understood that the that the above
`and the chip from the body to reduce the stresses
`described embodiments are merely illustrative of the
`transmitted from the body into the encapsulant
`principles of the invention. Various modi?cations and
`upon ?exing of the body.
`changes may be made thereto by those skilled in the art
`9. The method according to claim 8, characterized in
`which will embody the principles of the invention and
`that the shock-absorbing means are placed into the
`fall within the spirit and scope thereof.
`opening in the body to fit snugly therein.
`What is claimed is:
`_
`10. The method according to claim 8, characterized
`1. A personal data card comprising:
`in that the shock-absorbing means is embedded into the
`a body having an opening;
`body in proximity to the opening to substantially cir
`at least one semiconductor chip received within said
`cumscribe the periphery thereof.
`'
`opening;
`11. The method according to claim 8, characterized
`a mass of encapsulant admitted into the opening in
`in that said shock-absorbing device is placed within said
`said body to seal the chip therein; and
`body by directly extruding a viscous liquid elastomer
`a cover overlying the substrate to seal the opening
`precursor into said opening and then curing said elasto
`therein, characterized in that:
`mer to yield a resilient ring-like structure running along
`the body opening has a bottom wall to which the chip
`the inside wall of said opening.
`is bonded; and
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