Thin smart card module having strap on carrier

• US 8,141,786 B2
• Filed: 01/18/2008
• Issued: 03/27/2012
• Est. Priority Date: 01/18/2008
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Bhandarkar, Sarvotham, Hoang, Hoang
• Primary Examiner(s): Hess, Daniel
• Assistant Examiner(s): CHEDEKEL, TABITHA F
• Application Number:
  US12/016,815
• Publication Number:
  US 20090184166A1
• Time in Patent Office: 1,530 Days
• Field of Search: 235/492, 235/487, 257/666, 257/678, 257/778, 257/766, 257/99, 257/81, 257/100, 438/123, 438/25, 340/572.1, 340/572.5, 340/572.7
• US Class Current: 235/492
• CPC Class Codes: G06K 19/07718 the record carrier being manufactured in a continuous process, e.g. using endless rolls
• CPC Class Codes: G06K 19/07743 External electrical contacts
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/01327 Intermediate phases, i.e. intermetallics compounds
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

A Smart Card module with flip-assembled chip (101) on a metallic strap (112) adhering to an insulating substrate (111). Chip (101) is in the gap (122) of a metal carrier (120), strap (112) conductively attached to the carrier. Carrier (120) is designed to practically surround the chip, and has a thickness about equal to the chip thickness. Overall module thickness is less than 250 μm without dangerously thinning the chip. Additional strength may be acquired by filling any space of gap (122) not occupied by chip (101) with encapsulation compound (150). Metal carrier (120) further provides contact areas (120a, 120b) for higher level system interconnection (stacking of modules).

Claims

1. A Smart Card chip module comprising:

a semiconductor Smart Card chip having a first length, a width, a first thickness, and first and second metallic contact bumps of a height;

a substrate consisting of an insulating bottom layer and an metal top layer adhering continuously to the insulating bottom layer, the metal layer patterned into a strap having a first and a second half separated by a hiatus smaller than the first length;

a sheet-like metallic carrier, the carrier having a second thickness about equal to the sum of the first thickness and the bump height, the carrier patterned into a first and a second portion separated by a gap having a width at least equal to the first length for receiving the chip wherein a top of the carrier is substantially the same height from the substrate as the mounted chip;

the carrier conductively contacting the substrate so that the first carrier portion rests on and is electrically connected to the first strap half, the second carrier portion rests on and is electrically connected to the second strap half, and the hiatus is approximately in the center of the gap, wherein the insulating substrate layer bridges the carrier gap;

the chip in contact with the substrate so that the first length is within the carrier gap, the first bumps contacting the first strap half and the second bumps contacting the second strap half, wherein the chip spans over the hiatus between the halves and wherein the chip is electrically connectable to an external circuit via the strap and the carrier;

an adhesive polymer compound filling the space under the chip span and filling the hiatus; and

an encapsulation compound filling any space of the carrier gap not occupied by the chip.

2. The module of claim 1 further including metal lips protruding from the carrier portions so that the lips surround at least portions of the chip width.

3. The module of claim 1 wherein the strap further has a second length greater than the first length, and the carrier further has a third length greater than the second length.

4. The module of claim 1 wherein the carrier is a metallic leadframe.

5. The module of claim 4 wherein the leadframe includes copper and the second thickness ranges from about 80 to 250 μ

m.

6. The module of claim 1 wherein the encapsulation compound is a polymerized molding compound.

7. The module of claim 1 further including a layer of the encapsulation compound extending over the assembled chip and over carrier portions near the gap.

8. The module of claim 1 further including a layer of the encapsulation compound extending under the insulating bottom layer of the substrate and under carrier portions near the substrate strap.

9. The module of claim 1 wherein the bumps are made of gold.

10. The module of claim 1 wherein the chip first thickness is between about 75 and 225 μ

m and the chip first length is in the range from about 100 to 5000 μ

m.

11. A Smart Card chip module comprising:

a semiconductor Smart Card chip having a first length, a width, a first thickness, and first and second metallic contact bumps of a height;

a substrate consisting of an insulating bottom layer and an metal top layer adhering continuously to the insulating bottom layer, the metal layer patterned into a strap having a first and a second half separated by a hiatus smaller than the first length;

a sheet-like metallic carrier, the carrier having a second thickness about equal to the sum of the first thickness and the bump height, the carrier patterned into a first and a second portion separated by a gap having a width at least equal to the first length;

the carrier conductively contacting the substrate so that the first carrier portion rests on and is electrically connected to the first strap half, the second carrier portion rests on and is electrically connected to the second strap half, and the hiatus is approximately in the center of the gap, wherein the insulating substrate layer bridges the carrier gap;

the chip in contact with the substrate so that the first length is within the carrier gap, the first bumps contacting the first strap half and the second bumps contacting the second strap half, wherein the chip spans over the hiatus between the halves and wherein the chip is electrically connectable to an external circuit via the strap and the carrier;

an adhesive polymer compound filling the space under the chip span and filling the hiatus; and

an encapsulation compound filling any space of the carrier gap not occupied by the chip, wherein the insulating bottom layer of the substrate is made of polyethylene terephthalate (PET) in the thickness range from about 25 to 75 μ

m, and the metallic top layer is made of aluminum in the thickness range from about 5 to 25 μ

m.

12. A method for fabricating a Smart Card module comprising the steps of:

providing a plurality of semiconductor chips having a first length, a first thickness, and first and second metallic contact bumps of a height;

providing a first reel loaded with an insulating tape having an adhering metal layer configured as an array of straps in strap locations, each strap consisting of a first and a second half separated by a hiatus smaller than the first length;

assembling one chip to each strap by attaching the first bumps to the first metal half and the second bumps to the second metal half so that the chip spans over the hiatus;

filling the space under the chip span, and the strap hiatus, with an adhesive polymer compound;

re-loading the first reel with the assembled insulating tape;

providing a second reel loaded with a metallic tape patterned as rails holding carriers in the strap locations, each carrier consisting of a first and a second portion separated by a gap of a width at least equal to the first length, the metallic tape having a second thickness about equal to the sum of the first thickness and the bump height;

providing an assembly station to perform the steps of;

feeding the assembled insulating tape and the metallic tape concurrently through the equipment;

aligning each carrier over the respective strap so that the first carrier portion faces the first strap half, the second carrier portion faces the second strap half, and the strap hiatus, spanned by the chip, is approximately in the center of the carrier gap;

forming permanent contacts between the aligned carrier portions and strap halves to create modules with the chip positioned in the carrier gap;

filling encapsulation material into any space of the carrier gap not occupied by the assembled chip, thereby creating assembled modules; and

trimming the combined tapes by severing the supporting rails and cutting the insulating tape at the exposed edges of the carrier portions, thereby singulating the assembled modules into discrete modules.

13. The method of claim 12 wherein the step of forming permanent contacts is selected from a group of steps including:

crimping the aligned strap halves with the respective carrier portions;

dispensing a conductive adhesive compound on the first and second halves of each strap;

pressing each carrier and the respective strap together while applying heat, thereby attaching each strap half to the respective carrier portion; and

cooling the attached straps and carriers; and

dispensing a conductive adhesive compound on the first and second carrier portions;

pressing each strap and the respective carrier together while applying heat, thereby attaching each carrier portion to the respective strap half; and

cooling the attached carriers and straps.

14. The method of claim 12 further including the step of extending a layer of the encapsulation compound over the assembled chip and over certain carrier portions near the gap, while leaving carrier portions remote from the gap un-encapsulated, whereby the un-encapsulated carrier portions are available for electrical interconnection to the next level assembly.

15. The method of claim 12 further including the step of extending a layer of the encapsulation compound under the insulating bottom layer of the substrate and under certain carrier portions near the substrate strap, while leaving carrier portions remote from the gap un-encapsulated, whereby the un-encapsulated carrier portions are available for electrical interconnection to the next level assembly.

16. The method of claim 12 wherein the step of filling encapsulation compound employs a molding equipment and a polymerizable epoxy-based molding compound.

17. The method of claim 12 wherein the insulating tape is patterned so that portions of the carrier halves remote from the gap remain without substrate and thus available for electrical interconnection of the discrete module to the next level assembly.

18. The method of claim 12 wherein the conductive tape is a tape of metallic leadframes including rails and carriers.

19. The method of claim 12 wherein the insulating tape is made of PET and the metallic straps are made of aluminum.

20. The method of claim 12 wherein the assembly station includes rollers to guide and advance the tapes between them and to apply pressure onto the carriers and straps while freshly brought into contact.

21. The method of claim 13 wherein the step of dispensing a conductive adhesive compound is performed by the steps of:

providing a third reel loaded with a patterned adhesive film;

positioning the third reel so that the adhesive film is fed into the assembly station between the insulating tape and the conductive tape; and

aligning the patterned adhesive film so that the first and second strap halves of the assembled insulating tape become adhesive before pressing the conductive tape against the insulating tape.

22. The method of claim 13 wherein the conductive adhesive compound is selected from a group including isotropically conductive adhesives and anisotropically conductive adhesive.