MCM package with bridge connection

An MCM package with bridge connection mainly comprises a carrier, a first chip, a second chip and at least one conductive body. The carrier has an upper surface and an opposite lower surface, and a plurality of contacts formed on the upper surface of the carrier. The first chip has a first active surface, a first side surface and a first boding pad formed on the first active surface. Similarly, the second chip has a second active surface, a second side surface, and a second boding pad formed on the second active surface. Therein, the first side surface of the first chip is proximate to the second side surface of the second chip, and the first active surface is coplanar to the second active chip. Accordingly, one of the conductive body can be disposed continuously on the active surface and the second surface to electrically connect the first chip and the second chip.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to an MCM (Multi-chips Module) package. More particularly, the present invention is related to an MCM package with bridge connection.

2. Related Art

Integrated circuit (chip) packaging technology is becoming a limiting factor for the development in packaged integrated circuits of higher performance. Semiconductor package designers are struggling to keep pace with the increase in pin count, size limitations, low profile, and other evolving requirements for packaging and mounting integrated circuits.

Originally, the electrical connection between the chips comprises wire bonding connection and flip chip connection. In wire bonding connection, a wire bonder is disposed above the chip and then the tip of the conductive wire is melting to shape into a ball. Next, the conductive wire is bonded onto the bonding pad of the chip. Then, the wire bonder is moved and disposed above another bonding pad of the chip, and then another conductive wire will be bonded onto the corresponding bonding pad of the chip in the same way as mentioned above. In flip chip bonding, a plurality of bumps are formed on the bonding pads of the chip, and then flipped and bonded to another chip by a reflow process.

Next, a well-known wire bonding method utilized in a conventional MCM assembly package will be disclosed as below. As shown inFIG. 1, it illustrates the cross-sectional view of the conventional MCM package with wire bonding connection. The MCM package comprises a carrier10, a first chip12, a second chip14, a plurality of conductive wires160,162and164, an encapsulation18and a plurality of solder balls107. The carrier10, for example a substrate and a lead frame, has an upper surface102and an opposite lower surface104, a plurality of contacts106, a first die paddle105and a second die paddle109. The contacts106, the first die paddle105and the second die paddle109are formed on the upper surface102, and the first die paddle105and the second paddle109are encompassed with the contacts106. As mentioned above, the first chip12has a first active surface122, a first back surface124and a plurality of first bonding pads126formed on the first active surface122. It is should be noted that the first chip12is mounted onto the first die paddle105of the carrier10via an adhesive105and electrically connected to the carrier10via the conductive wire160. Therein one end of the conductive wire160is bonded to the bonding pad126and the other end of the conductive wire160is bonded onto the contact106of the carrier10.

Similarly, the second chip14is mounted onto the second die paddle109of the carrier10via an adhesive (not shown) and electrically connected to the carrier10via the conductive wire162. Therein one end of the conductive wire162is bonded to the bonding pad146and the other end of the conductive wire162is bonded onto the contact108of the carrier10. In addition, the first chip12is electrically connected to the second chip14through the conductive wire164. Furthermore, an encapsulation18encapsulates the first chip12, the second chip14and the upper surface102of the carrier10and said conductive wires160,162and164.

In the above-mentioned MCM package, the first chip12is electrically connected to the second chip14through the conductive wire164. However, the cross-sectional area of the conductive wire164is small and the length of the conductive wire164is long so as to cause the characterization impedance to be mismatched and to cause the signal to be attenuated. Besides, when the high-frequency circuits are performed, the parasitics of the inductance and the capacitor will be induced to cause the signal to be reflected. In addition, the cross-sectional area of the conductive wire for connecting the first chip is so small that the grounding connection will become worse.

Therefore, providing another MCM package to solve the mentioned-above disadvantages is the most important task in this invention.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems, an objective of this invention is to provide an MCM package with bridge connection, which can shorten the distance of the electrical connection between the chips so as to upgrade the electrical performance of the MCM package.

To achieve the above-mentioned objective, an MCM package with bridge connection is provided, wherein the MCM package comprises a carrier, a first chip, a second chip, a conductive body and a plurality of solder balls. The carrier has an upper surface, an opposite lower surface and a plurality of contacts on the upper surface of the carrier. Moreover the first chip has a first active surface and a plurality of first bonding pads formed on the first active surface. Similarly, the second chip has a second active surface and a plurality of second bonding pads formed on the second active surface. Therein, the first chip and the second chip are both electrically connected to the carrier and disposed on the upper surface of the carrier. Besides, the first chip and the second chip is disposed in close proximity or directly connected with each other, and the first active surface is substantially coplanar to the second active surface. Most important, said MCM package is characterized in that there is a conductive body, e.g. tin-lead alloy, lead-free alloy and conductive epoxy, disposed on the first active surface and the second active surface continuously so as to electrically connect one of the first bonding pads and one of the second bonding pads. Therein, the first bonding pads are disposed on the edge of the fist active surface of the first chip and the second bonding pads are disposed on the edge of the second active surface of the second chip. In such a manner, the first bonding pads and the second bonding pads are disposed in proximity to each other.

As specified above, the MCM package further comprises an encapsulation for encapsulating the first chip, the second chip, the upper surface of the carrier and the conductive body.

According to this invention, the electrical connection between the chips is a conductive body. Thus, the distance of the electrical connection between the chips is short and the cross-sectional area for transmitting signal is large so as to lower the characterization impedance to prevent the signal from being attenuated. Furthermore, this invention can prevent the parasitics of the inductance and the capacitor from being induced so as to be suitable to the assembly package designed for performing high-circuits.

DETAILED DESCRIPTION OF THE INVENTION

The MCM package with bridge connection according to the preferred embodiment of this invention will be described herein below with reference to the accompanying drawings, wherein the same reference numbers refer to the same elements.

In accordance with a first preferred embodiment as shown inFIG. 2, there is provided an MCM package. The MCM package mainly comprises a carrier20, a first chip22, a second chip24, and a conductive body264. The carrier20has an upper surface202, an opposite lower surface204, a plurality of contacts206and208formed on the upper surface202of the carrier20. The first chip22has a first active surface222and at least one first bonding pad226formed on the active surface222of the first chip22. Similarly, the second chip24has a second active surface242and at least one second bonding pad246formed on the second surface242of the second chip24. Therein, the first chip22and the second chip24are both mounted on the carrier20through an adhesive. Besides, the conductive wire260electrically connects the first bonding pad226of the first chip22and the contact206of the carrier20, and the conductive wire262electrically connects the second bonding pad246of the second chip24and the contact208of the carrier20.

In addition, the first side surface221of the first chip22is in close proximity to the second side surface241of the second chip24, and the first active surface222of the first chip22is coplanar to the second surface242of the second chip24. Moreover, the first bonding pad226and the second bonding pad are respectively disposed on the edge of the first active surface222of the first chip22and the edge of the second active surface242of the second chip24. The first conductive body264, e.g. tin-lead alloy, lead-free alloy and conductive epoxy, is disposed on the first active surface222of the first chip22and the second active surface242of the second chip24continuously so as to electrically connect the first bonding pad228of the first chip22and the second bonding pad248of the second chip24. As shown above, the MCM package further comprises an encapsulation28for encapsulating the first chip22, the second chip24, the upper surface202of the carrier20and the conductive body264.

Referring toFIG. 3, a second preferred embodiment is disclosed. There is a gap between the first side surface221of the first chip22and the second side surface241of the second chip24and a filler29, e.g. non-conductive epoxy, is filled into the gap. The upper surface292of the filler29is coplanar to the first active surface222of the first chip22and the second active surface242of the second chip24. Next, a screen-printing method is performed so as to form a solder material above the first bonding pad226, the second bonding pad246and the upper surface292of the filler29, wherein the solder material at least comprises flux and metal powder (not shown). Then a reflow process is performed so that the metal powder is melted to form a conductive body264for electrically and physically connecting the first bonding pad226and the second bonding pad246. Therein, the conductive body can also be solder alloy, lead-free alloy or other conductive material without lead as provided in the first embodiment.

Next, referring toFIG. 4, a third preferred embodiment is disclosed. In this embodiment, there is an opening201formed in the carrier20, and passing through the upper surface202of the carrier20and lower surface204of the carrier20. The first chip22and the second chip24are disposed in the opening201, and the encapsulation28covers a portion of the upper surface202of the carrier20, the first chip22, the second chip24and the conductive body264so that the first back surface224of the first chip22and the second back surface244of the second chip24are exposed. Thereby, the thickness of the package will be reduced.

Moreover, as mentioned above and referring toFIG. 5, a fourth preferred embodiment is disclosed. In this MCM package of said fourth embodiment, a heat spreader21is disposed below the carrier20and attached to the lower surface204of the carrier20. Accordingly, the first chip22and the second chip24are disposed on the heat spreader21so as to upgrade the capability and performance for heat dissipation.

It is should be noted thatFIG. 6shows a fifth preferred embodiment. The carrier20also has an opening201formed therein and the first chip22and the second chip24are disposed in the opening201continuously, and the size of the opening201is substantially the same as the size of the first chip22and the second chip24so that the third side surface223of the first chip22, the fourth side surface224of the second chip24are directly contacted to the inner wall203of the opening20. Moreover, the first active surface222of the first chip22, the second active surface242of the second chip24and the upper surface202of the carrier20are coplanar to each other. Next, a second conductive body266is formed to electrically connect the first chip22and the carrier20. Correspondingly, a third conductive body268is formed to electrically connect the second chip24and the carrier20. However, similar to the first embodiment, the first conductive body264is formed on the first active surface222of the chip22and the second active surface242of the second chip24so as to electrically connect the first chip22and the second chip24.

No matter which assembly process is performed to form such embodiments as shown above, a plurality of solder balls207can be implemented on the upper surface202of the carrier20or the lower surface204of the carrier20for electrically connecting to the outside or another external circuits.

In the aforementioned embodiments, the bonding pads of the chips can be electrically connected with each other through the conductive body, so the distance of the electrical connection between the bonding pads of the chips and between the bonding pad and the contact of the carrier are short, and the cross-sectional area for transmitting signal are large. Thus the transmission impedance can be reduced to prevent the signal from being attenuated. Furthermore, this invention can prevent the parasitics of the inductance and the capacitor from being induced so as to be suitable to the assembly package designed for performing high-circuits. Besides, the contacting areas between the conductive body and the contact of the carrier, and the contacting areas between the conductive body and the bonding pad of the chip are large, and the conductive body is directly contacted to the bonding pad of the chip so as to prevent the characterization impedance of the conductive body from being mismatched with corresponding contacts or bonding pads. In addition, this invention can improve the electrical performance of the MCM package so that the grounding connection will become better.

As mentioned above, the solder material is formed on the contacts or bonding pads by the method of screen-printing. However, the solder material is formed not only by said screen-printing method but also by the method as following shown. Referring toFIG. 7to9, a mask layer254is formed on the first active surface222of the first chip22, the second active surface242of the second chip24, and the upper surface202of the carrier20. When the mask layer254is a photosensitive material, the openings256can be formed by performing exposure process so as to expose the first bonding pad226, the second bonding pad246and the contact208of the carrier20through the openings256. When the mask layer254is a non-photosensitive material, the openings256can be formed by performing development and etching process so as to expose the second bonding pad246, the second bonding pad246and the contact208of the carrier20through the openings256. Next, a solder material258can be filled into the opening256defined by the mask layer254as shown in FIG.8. Therein, the solder material comprises flux (not shown) and metal powder, wherein the metal powder is mixed up with metal powder equally. Then a reflow process is performed so as to make the metal powder melted and solidified. Thus a conductive body259is formed on the first bonding pad226, the second bonding pad246and the carrier contact208as shown inFIG. 9, wherein the first bonding pad226is electrically connected to the second bonding pad246via the conductive body259. Afterwards, the mask layer254is removed and the following processes are performed as specified in the first embodiment. It should be noted that the reference numeral of each element shown inFIGS. 4,5,6,7,8and9is corresponding the same reference one provided in FIG.3.

Although the invention has been described in considerable detail with reference to certain preferred embodiments, it will be appreciated and understood that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.