# Patent

## Title
Chip package structure

## Abstract

A chip package structure including a first substrate, a second substrate, a plurality of bumps, a first B-staged adhesive layer and a second B-staged adhesive layer is provided. The first substrate has a plurality of first bonding pads. The second substrate has a plurality of second bonding pads, and the second substrate is disposed above the first substrate. The bumps are disposed between the first substrate and the second substrate, wherein each of the first bonding pads is respectively electrically connected to one of the second bonding pads via one of the bumps. The first B-staged adhesive layer is adhered on the first substrate. The second B-staged adhesive layer is adhered between the first B-staged adhesive layer and the second substrate, wherein the first B-staged adhesive layer and the second B-staged adhesive layer encapsulate the bumps.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This is a continuation-in-part application of patent application Ser. No. 11/234,774, filed on Sep. 22, 2005, which is now allowed. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a chip package structure. More particularly, the present invention relates to a chip package structure with better reliability.
2. Description of Related Art
Following the increase of input/output contacts of an integrated circuit, chip package technology has become more and more diversified. This is due to the fact that Flip Chip (FC) Interconnect technology minimizes the thickness of the chip package, and reduces signal transmission path, etc. The most common used chip package structures applying the flip chip interconnect technology is, for example, Flip Chip Ball Grid Array (FC/BGA) package and the Flip Chip Pin Grid Array (FC/PGA) package.
Flip chip interconnect technology employs the method of defining area array by disposing a plurality of bonding pads onto the active surface of the chip and forming a plurality of bumps on the bonding pads, respectively. Next, the chip is flipped to connect the bonding bumps of the chip and a plurality of contact pads disposed on a carrier such as a circuit substrate. Therefore, the chip is electrically and mechanically connected to the carrier through the bumps. Further, the chip can be electrically connected to external electronic devices via the internal circuits of the carrier. Generally speaking, the bumps has several types such as the solder bump, the gold bump, the copper bump, the conductive polymer bump, the polymer bump, etc.
FIG. 1 is a schematic cross-sectional view showing a flip chip package structure having polymer bumps. Referring to FIG. 1, the flip chip package structure 100 comprises a substrate 110, a plurality of polymer bumps 120, a chip 130 and solder 140. The substrate 110 has a surface 110a and a plurality of contact pads 112 disposed on the surface 110a. The chip 130 has an active surface 130a and a plurality of bonding pads 132 disposed on the active surface 130a. The polymer bumps 120 made of polymer material with conductive property are respectively arranged between the contact pads 112 and the bonding pads 132 for electrically connecting the substrate 110 and the chip 130. The surface A of the solder 140 is adhered to the contact pad 112 and the surface B of the solder 140 is adhered to the polymer bump 120. Therefore, when external force or thermal stress (not shown) is applied to the flip chip package structure 100, the solder 140 may peel from the contact pads 112 such that the polymer bumps 120 can not be electrically connected to the contact pads 112. Obviously, the reliability of the flip chip package structure 100 is lower.
SUMMARY OF THE INVENTION
The present invention is to provide a chip package structure having enhanced reliability.
As embodied and broadly described herein, the present invention provides a chip package structure including a first substrate, a second substrate, a plurality of bumps, a first B-staged adhesive layer and a second B-staged adhesive layer. The first substrate has a plurality of first bonding pads. The second substrate has a plurality of second bonding pads, and the second substrate is disposed above the first substrate. The bumps are disposed between the first substrate and the second substrate, wherein each of the first bonding pads is respectively electrically connected to one of the second bonding pads via one of the bumps. The first B-staged adhesive layer is adhered on the first substrate. The second B-staged adhesive layer is adhered between the first B-staged adhesive layer and the second substrate, wherein the first B-staged adhesive layer and the second B-staged adhesive layer encapsulate the bumps. The first B-staged adhesive layer and the second B-staged adhesive layer can be whole layers or patterned layers.
According to an embodiment of the present invention, the bumps may be stud bumps or plating bumps.
According to an embodiment of the present invention, the first B-staged adhesive layer and the second B-staged adhesive layer are non-conductive.
According to an embodiment of the present invention, the first B-staged adhesive layer comprises a plurality of first B-staged adhesive pillars and the second B-staged adhesive layer comprises a plurality of second B-staged adhesive pillars. In an alternative embodiment, the first B-staged adhesive pillars are conductive while the second B-staged adhesive pillars are conductive or non-conductive. In another embodiment, the first B-staged adhesive pillars are non-conductive while the second B-staged adhesive pillars are conductive or non-conductive.
According to an embodiment of the present invention, the first substrate and the second substrate can be both chips.
According to an embodiment of the present invention, one of the first substrate and the second substrate can be a chip.
According to an embodiment of the present invention, the glass transition temperature of the first B-staged adhesive layer may be greater than, equal to or smaller than the glass transition temperature of the second B-staged adhesive layer.
According to an embodiment of the present invention, the chip package structure further comprises a carrier and a plurality of bonding wires. The first substrate and the second substrate are disposed on the carrier, and the first substrate is electrically connected to the carrier through the bonding wires.
According to an embodiment of the present invention, the size of the first B-staged adhesive layer is smaller than the size of the second B-staged adhesive layer. Additionally, the first B-staged adhesive layer may comprise a plurality of first B-staged adhesive pillars.
In summary, the chip package structure of the present invention utilizes a first B-staged adhesive layer and a second B-staged adhesive layer to encapsulate the bumps disposed between the first substrate and the second substrate. When an external force or thermal stress is applied to the chip package structure, the first B-staged adhesive layer and the second B-staged adhesive layer are capable of preventing the bumps from damage, such that reliability of the chip package structure is further enhanced.



BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
FIG. 1 is a schematic cross-sectional view showing a flip chip package structure having polymer bumps.
FIG. 2A and FIG. 2B are schematic cross-sectional views illustrating chip package structures according to an embodiment of the present invention.
FIG. 3A to FIG. 3D are schematic cross-sectional views illustrating chip package structures according to another embodiment of the present invention.
FIG. 4 is a schematic cross-sectional view illustrating a stacked-type chip package structure according to an embodiment of the present invention.
FIGS. 5-7 are schematic cross-sectional views illustrating stacked-type chip package structures according to various embodiments of the present invention.



DESCRIPTION OF THE EMBODIMENTS
Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
FIG. 2A and FIG. 2B are schematic cross-sectional views illustrating chip package structures according to an embodiment of the present invention. Referring to FIG. 2A and FIG. 2B, the chip package structure 200 of the present invention comprises a first substrate 210, a second substrate 220, a plurality of bumps 230, a first B-staged adhesive layer 240a and a second B-staged adhesive layer 240b. The first substrate 210 has a plurality of first bonding pads 212. The second substrate 220 has a plurality of second bonding pads 222, and the second substrate 220 is disposed above the first substrate 210. The bumps 230 are disposed between the first substrate 210 and the second substrate 220, wherein each of the first bonding pads 212 is respectively electrically connected to one of the second bonding pads 222 via one of the bumps 230. The first B-staged adhesive layer 240a is adhered on the first substrate 210. The second B-staged adhesive layer 240b is adhered between the first B-staged adhesive layer 240a and the second substrate 220, wherein the first B-staged adhesive layer 240a and the second B-staged adhesive layer 240b encapsulate the bumps 230. Additionally, composition of the first B-staged adhesive layer 240a can be different from or substantially the same with that of the second B-staged adhesive layer 240b. As shown in FIG. 2A and FIG. 2B, the first B-staged adhesive layer 240a is adhered on the surface S1 of the first substrate 210 and the second B-staged adhesive layer 240b is adhered on the surface S2 of the second substrate 220. It is noted that the invention utilizes the first B-staged adhesive layer 240a and the second B-staged adhesive layer 240b to enhance the adhesion between the first substrate 210 and the second substrate 220, such that reliability of the chip package structure 200 can be enhanced.
As shown in FIG. 2A and FIG. 2B, in the present embodiment, the thickness of the first B-staged adhesive layer 240a is substantially equal to the thickness of the second B-staged adhesive layer 240b. However, base on actual design requirements, the thickness of the first B-staged adhesive layer 240a may also be different from that of the second B-staged adhesive layer 240b. 
The first substrate 210 comprises a plurality of first bonding pads 212 arranged on a surface S1 thereof. The second substrate 220 is arranged above the first substrate 210 and also comprises a plurality of second bonding pads 222 arranged on a surface S2 thereof. According to the present embodiment, the first substrate 210 and the second substrate 220 can be both chips. In another embodiment of the invention, one of the first substrate 210 and the second substrate 220 is chip. The types of the first substrate 210 and the second substrate 220 are not limited in the present invention. The bumps 230 are arranged between the first bonding pads 212 and the second bonding pads 222. Specifically, the upper end of each bump 230 contacts with the second bonding pad 222 and the lower end of each bump 230 contacts with the first bonding pads 212.
In the present embodiment, the bumps 230 are stud bumps 230a (shown in FIG. 2A), and the stud bumps 230a can be gold stud bumps or copper stud bumps. In another embodiment of the present invention, the bumps 230 may be plating bumps 230b (shown in FIG. 2B). The plating bumps 230b may be gold bumps, copper bumps or other conductive bumps. Each of the stud bumps 230a or each of the plating bumps 230b is encapsulated by one of the adhesive pillars 240a′. 
According to the present embodiment, the first B-staged adhesive layer 240a comprises a plurality of first B-staged adhesive pillars 240a′ and the second B-staged adhesive layer 240b comprises a plurality of second B-staged adhesive pillars 240b′, wherein the first B-staged adhesive pillars 240a′ are adhered on the surface S1 of the first substrate 210 and the second B-staged adhesive pillars 240b′ are adhered on the surface S2 of the second substrate 220. In the present embodiment, the first B-staged adhesive pillars 240a′ are conductive or non-conductive while the second B-staged adhesive pillars 240b′ are conductive or non-conductive. Since the first B-staged adhesive pillars 240a′ are electrically insulated from one another and the second B-staged adhesive pillars 240b′ are electrically insulated from one another, the short circuit between the bumps 230 can be prevented even though the first B-staged adhesive pillars 240a′ and the second B-staged adhesive pillars 240b′ are both conductive.
In the present embodiment, the first B-staged adhesive layer 240a and the second B-staged adhesive layer 240b can be obtained from 8008 or 8008HT of ABLESTIK, and the glass transition temperature of which is between about 80° C. and about 300° C. Additionally, the first B-staged adhesive layer 240a and the second B-staged adhesive layer 240b can also be obtained from 6200, 6201 or 6202C of ABLESTIK or obtained from SA-200-6, SA-200-10 provided by HITACHI Chemical CO., Ltd., and the glass transition temperature of which is between about −40° C. and about 150° C. The glass transition temperature of the first B-staged adhesive layer 240a is greater than, equal to or smaller than the glass transition temperature of the second B-staged adhesive layer 240b. Additionally, some conductive particles (e.g. silver particles, copper particles, gold particles) are doped in the first B-staged adhesive layer 240a and the second B-staged adhesive layer 240b, for example.
FIG. 3A to FIG. 3D are schematic cross-sectional views illustrating chip package structures according to another embodiment of the present invention. Referring to FIG. 3A and FIG. 3B, the chip package structure 200′ of the present embodiment is similar to the chip package structure 200 shown in FIG. 2A and FIG. 2B except that the first B-staged adhesive layer 240a and the second B-staged adhesive layer 240b entirely fill the gaps between the bumps 230. Specifically, the first B-staged adhesive layer 240a and the second B-staged adhesive layer 240b are both non-conductive so as to prevent short circuit between the bumps 230.
Referring to FIG. 3C, the chip package structure 200′′ of the present embodiment is similar to the chip package structure 200′ shown in FIG. 3A except that the size D2 of the first B-staged adhesive layer 240a is different from the size D2 of the second B-staged adhesive layer 240b. As shown in FIG. 3C, the size D1 of the first B-staged adhesive layer 240a is smaller than the size D2 of the second B-staged adhesive layer 240b such that a portion area of the first substrate 210 is exposed by the first B-staged adhesive layer 240a. The first B-staged adhesive layer 240a entirely covers the surface S1 of the first substrate 210 except areas occupied by the bumps 230, and the second B staged adhesive layer 240b exposes peripheral region of the surface S2 of the second substrate 220.
Referring to FIG. 3D, the chip package structure 200′′′ of the present embodiment is similar to the chip package structure 200′′ shown in FIG. 3C except that the first B-staged adhesive layer 240a comprises a plurality of first B-staged adhesive pillars 240a′. 
FIG. 4 is a schematic cross-sectional view illustrating a stacked-type chip package structure according to an embodiment of the present invention. Referring to FIG. 4, the stacked-type chip package structure 400 comprises a carrier 410, a first chip 210′, a second chip 220′, a plurality of bumps 230, a first B-staged adhesive layer 240a, a second B-staged adhesive layer 240b and a plurality of bonding wires 420. The arrangement of the first chip 210′, the second chip 220′, the bumps 230, the first B-staged adhesive pillars 240a′ and the second B-staged adhesive pillars 240b′ is substantially the same with the arrangement as shown in FIG. 2A or FIG. 2B. In the present embodiment, the first chip 210′ is bonded to the carrier 410 through an adhesive layer 430 (e.g. epoxy, silver paste, DAF, and so on), and is electrically connected to the carrier 410 via the bonding wires 420. The carrier 410 such as the printed circuit board (PCB). The PCB may be FR4, FR5, BT, PI circuit substrate. Specifically, the first chip 210′ has wire bonding pads 214 electrically connected to the carrier 410 via the bonding wires 420.
FIGS. 5-7 are schematic cross-sectional views illustrating stacked-type chip package structures according to various embodiments of the present invention. Referring to FIG. 5, the stacked-type chip package structure 400a comprises a carrier 410, a first chip 210′, a second chip 220′, a plurality of bumps 230, a first B-staged adhesive layer 240a, a second B-staged adhesive layer 240b and a plurality of bonding wires 420. The arrangement of the first chip 210′, the second chip 220′, the bumps 230, the first B-staged adhesive layer 240a and the second B-staged adhesive layer 240b is substantially the same with the arrangement as shown in FIG. 3A or FIG. 3B. The first chip 210′ is bonded to the carrier 410 through an adhesive layer 430 (e.g. epoxy, silver paste, DAF, and so on), and is electrically connected to the carrier 410 via the bonding wires 420. Specifically, the first chip 210′ has wire bonding pads 214 electrically connected to the carrier 410 via the bonding wires 420. An end of the bonding wires 420 connected to the wire bonding pads 214 is encapsulated by the first B-staged adhesive layer 240a. The stand-off between the first chip 210′ and the second chip 220′ is maintained by at least one of the first B-staged adhesive layer 240a and the second B-staged adhesive layer 240b, such that the bonding wires 420 can be protected from damage.
Referring to FIG. 6 and FIG. 7, in the stacked-type chip package structure 400b and 400c, the arrangement of the first chip 210′, the second chip 220′, the bumps 230, the first B-staged adhesive layer 240a and the second B-staged adhesive layer 240b may also be the same as or similar with the above-mentioned embodiments shown in FIG. 3C and FIG. 3D. As shown in FIG. 6 and FIG. 7, wire bonding pads 214 of the first chip 210′ are exposed by the first B-staged adhesive layer 240a or the first B-staged adhesive pillars 240a′ such that the bonding wires 420 are not encapsulated by the first B-staged adhesive layer 240a or the first B-staged adhesive pillars 240a′. 
It will be apparent to those skilled in the art that various modifications and variations may be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.

## Claims

1. A chip package structure, comprising:
a first substrate having a plurality of first bonding pads, wherein the first bonding pads includes a plurality of bump pads and a plurality of wire bonding pads;
a second substrate having a plurality of second bonding pads, the second substrate being disposed above the first substrate;
a plurality of bumps disposed between the first substrate and the second substrate, wherein each of the bump pads is respectively electrically connected to one of the second bonding pads via one of the bumps;
a first B-staged adhesive layer adhered on the first substrate; and
a second B-staged adhesive layer adhered between the first B-staged adhesive layer and the second substrate, wherein the first B-staged adhesive layer and the second B-staged adhesive layer encapsulate the bumps, the first B-staged adhesive layer comprises a plurality of first B-staged adhesive pillars, and the second B-staged adhesive layer comprises a plurality of second B-staged adhesive pillars;
a carrier; and
a plurality of bonding wires, wherein the first substrate and the second substrate are disposed on the carrier, each of the bonding wires is electrically connected to the carrier through one of the wire bonding pads directly, and the bonding wires are not in contact with the bumps.

2. The chip package structure according to claim 1, wherein the bumps comprise stud bumps or plating bumps.

3. The chip package structure according to claim 1, wherein the first B-staged adhesive layer and the second B-staged adhesive layer are non-conductive.

4. The chip package structure according to claim 1, wherein the first substrate and the second substrate are both chips.

5. The chip package structure according to claim 1, wherein one of the second substrate and the first substrate is a chip.

6. The chip package structure according to claim 1, wherein a glass transition temperature of the first B-staged adhesive layer is greater than a glass transition temperature of the second B-staged adhesive layer.

7. The chip package structure according to claim 1, wherein a glass transition temperature of the first B-staged adhesive layer is equal to or smaller than a glass transition temperature of the second B-staged adhesive layer.

8. The chip package structure according to claim 1, wherein an end of each of the bonding wires is encapsulated by the first B-staged adhesive layer.

9. The chip package structure according to claim 1, wherein an end of each of the bonding wires is not encapsulated by the first B-staged adhesive layer.

10. The chip package structure according to claim 1, wherein a thickness of the first B-staged adhesive layer is substantially equal to a thickness of the second B-staged adhesive layer.

11. The chip package structure according to claim 1, wherein the first B-staged adhesive pillars are conductive.

12. The chip package structure according to claim 11, wherein the second B-staged adhesive pillars are conductive.

13. The chip package structure according to claim 11, wherein the second B-staged adhesive pillars are non-conductive.

14. The chip package structure according to claim 1, wherein the first B-staged adhesive pillars are non-conductive.

15. The chip package structure according to claim 14, wherein the second B-staged adhesive pillars are conductive.

16. The chip package structure according to claim 14, wherein the second B-staged adhesive pillars are non-conductive.

17. The chip package structure according to claim 1, wherein a size of the first B-staged adhesive layer is smaller than a size of the second B-staged adhesive layer.

18. The chip package structure according to claim 17, wherein the first B-staged adhesive layer comprises a plurality of first B-staged adhesive pillars.