Integrated circuit package system with leadfinger support

An integrated circuit package system including forming a leadframe having a lead with a leadfinger support of a predetermined height, and attaching an integrated circuit die with an electrical interconnect at a predetermined collapse height determined by the predetermined height of the leadfinger support.

TECHNICAL FIELD

The present invention relates generally to package systems, and more particularly to a system for an integrated circuit package.

BACKGROUND ART

Protecting integrated circuits in ever decreasing packages has become increasingly difficult and costly. Integrated circuits or semiconductors usually are encapsulated in a package prior to installation into an electronic system. Device, die or chip packages perform several key functions such as, connecting integrated circuits to an electronic system at a next level of integration or hierarchy, physical protection from further handing and additional manufacturing processes, environmental protection including environments within multiple levels of electronic systems and heat dissipation from the integrated circuits and other components. These functions present chipmakers with a number of design and manufacturing challenges that must also be balanced with factors such as cost and pricing.

Flip-chip packaging is one type of electronic chip packaging technology, and has been in existence for many years. Flip-chip packaging has progressed to include a wide variety of materials and methods for bumping and attaching devices. Although the technology has progressed, challenges still exist in solving problems with manufacturing yield, device reliability, higher frequency applications, tighter space requirements, reduced costs, and general device performance. Many of the challenges to solving these continuing problems can be attributed to some key packaging issues including bump collapse level, bump spread distance and paddle damage such as paddle delamination.

A bump is placed onto the integrated circuit die contact, heated, and cooled to reflow the alloy to form a bump and to bond the bump to the integrated circuit die. The integrated circuit die is then assembled with the package so that the bump rests upon the corresponding package contact. The assembly is heated and cooled to bond the bump to the package. This attaches the integrated circuit die to the package and electrically connects the contacts for conducting electrical signals, with the integrated circuit die and the package spaced apart by the bump. During reflow, the bump tends to collapse under the weight of the integrated circuit die, creating a collapsed configuration that tends to concentrate stresses at the solder bonds and reduces the spacing thereby restricting access for encapsulation, cleaning or other post-connection operations.

Integrated circuit packages also provide electrical interconnection of integrated circuits to an electronic system at the next level of integration or hierarchy. A leadframe is one common means of electrical interconnection. The leadframe is formed from electrically conductive material, which is formed into leads. The lead ends are electrically connected to the integrated circuit die and the next level electronic system including external circuitry such as a printed circuit board. The leadframe also often include a die attach paddle to mount the integrated circuit die. The large surface area, exposed edges and narrow component spacing of the die attach paddle are often susceptible to manufacturing problems including damage during encapsulation of the integrated circuit package.

Integrated circuits are used in many portable electronic products, such as cell phones, portable computers, voice recorders, etc. as well as in many larger electronic systems, such as cars, planes, industrial control systems, etc. Across virtually all applications, there continues to be demand for reducing the size and increasing performance of the devices. The intense demand is no more visible than in portable electronics that have become so ubiquitous. As the demand for smaller electronic devices grows, manufacturers are seeking ways to reduce the size of the packaged integrated circuits. To meet these needs, packaging technologies are increasingly using smaller area designs with smaller features.

Thus, a need still remains for an integrated circuit package system to provide improved reliability and manufacturing yield with smaller features in smaller area. In view of the increasing demand for improved density of integrated circuits and particularly portable electronic products, it is increasingly critical that answers be found to these problems.

DISCLOSURE OF THE INVENTION

The present invention provides forming a leadframe having a lead with a leadfinger support of a predetermined height, and attaching an integrated circuit die with an electrical interconnect at a predetermined collapse height determined by the predetermined height of the leadfinger support.

BEST MODE FOR CARRYING OUT THE INVENTION

Likewise, the drawings showing embodiments of the apparatus/device are semi-diagrammatic and not to scale and, particularly, some of the dimensions are for the clarity of presentation and are shown greatly exaggerated in the drawing FIGs. Similarly, although the sectional views in the drawings for ease of description show the invention with surfaces as oriented downward, this arrangement in the FIGs. is arbitrary and is not intended to suggest that invention should necessarily be in a downward direction. Generally, the device can be operated in any orientation. In addition, the same numbers are used in all the drawing FIGs. to relate to the same elements.

Referring now toFIG. 1, therein is shown a cross-sectional view of an integrated circuit package system100in an embodiment of the present invention. The integrated circuit package system100includes a leadframe102having leads104with a leadfinger support106. The leadfinger support106may be formed by an etch process applied to the leads104. The leadfinger support106may be formed as a protruding shape, such as a stud vertically protruding from the leads104. The leads104may also include a wetting surface108around the leadfinger support106.

The integrated circuit package system100also includes an integrated circuit die110having electrical interconnects112, such as solder bumps. The electrical interconnects112may be formed on the integrated circuit die110and flowed on the leadfinger support106providing electrical connectivity between the integrated circuit die110and the leadframe102.

The leadfinger support106provides control for a collapse level or height of the electrical interconnects112on the leads104. The wetting surface108, such as a recess in the leads104, provides a physical resistance to the wetting or spread distance of the electrical interconnects112. The control of the collapse level and the spread distance of the electrical interconnects112provide a substantially controlled position of the integrated circuit die110along both the horizontal plane and vertical axes. It has been discovered that the substantially controlled position of the integrated circuit die110provides for an optional die attach paddle (not shown). The substantially controlled position of the integrated circuit die110also provides reduced stress and improved spacing for post-connection operations such as encapsulation or cleaning.

The integrated circuit package system100may also include an encapsulant114. The encapsulant114covers and protects the integrated circuit die110and the leadframe102. An encapsulating process such as molding, bonding or sealing may be used to apply the encapsulant114. The encapsulating process applies the encapsulant114over the integrated circuit die110, the electrical interconnects112, the leadframe102, the leads104, the leadfinger support106and the wetting surface108. The encapsulant114may conform to the integrated circuit die110and the leadframe102, although it is understood that the encapsulant may cover the integrated circuit die110and the leadframe102with other encapsulating processes.

Referring now toFIG. 2, therein is shown an isometric view of the leads104having the leadfinger support106. The leads104also include the wetting surface108and external connections202. The external connections202provide electrical connectivity to an electronic system (not shown) at a next level of integration or hierarchy such as a printed circuit board. An inner tip of the leads104may be etched to a reduced height while leaving portions protruding to form the leadfinger support106. The reduced height of the inner tip of the leads104forms the wetting surface108. It has been discovered that the leads104electrically connect the integrated circuit die110ofFIG. 1to the electronic system while providing control for the collapse level and the spread distance of the electrical interconnects112.

The shape and size of the leadfinger support106and the wetting surface108of the leads104provide a predetermined extent for the collapse level and the spread distance. For illustrative purposes, the leadfinger support106is shown as a rectangular prism, although it is understood that other shapes, number of shapes or sizes may be used.

Referring now toFIG. 3, therein is shown a cross-sectional view of the integrated circuit package system100in a die placement phase. The integrated circuit package system100includes the integrated circuit die110over the leadframe102. The integrated circuit die110and the leadframe102are substantially fixed in a predetermined position. The electrical interconnects112are formed on an active surface302of the integrated circuit die110. Each of the electrical interconnects112on the active surface302of the integrated circuit die110are substantially aligned to each of the leadfinger support106of the leadframe102.

A fixture (not shown) may hold the integrated circuit die110and the leadframe102substantially aligned in the horizontal plane. A wetting interface material (not shown) may be applied between the electrical interconnects112and the leadfinger support106. The wetting interface material may provide adhesion between the electrical interconnects112and the leadfinger support106. The fixture may allow vertical movement of the integrated circuit die110or the leadframe102, or the fixture may release the integrated circuit die110or the leadframe102for attachment.

Referring now toFIG. 4, therein is shown a cross-sectional view of the integrated circuit package system100in a die attachment phase. The integrated circuit package system100includes the integrated circuit die110mounted over the leadframe102. An attachment process, such as an attach reflow, provides flowing of the electrical interconnects112on the active surface302around the leadfinger support106of the leads104. The attachment process may include a thermal or similar process providing a liquefying or partial liquefying of the electrical interconnects112. The electrical interconnects112in a liquid or partial liquid state flows around the leadfinger support106and over the wetting surface108of the leads104.

The flowing of the electrical interconnects112results in a collapse of the electrical interconnects112and a position of the integrated circuit die110at a collapse level402determined by the size and shape of the leadfinger support106. The flowing of the electrical interconnects112also results in the wetting of the electrical interconnects112over the wetting surface108to a spread distance404determined by the size and shape of the wetting surface108. Each of the electrical interconnects112may overlap one each of the leadfinger support106and the wetting surface108to an extent predetermined by the size and shape of the leadfinger support106and the wetting surface108.

Referring now toFIG. 5, therein is shown a cross-sectional view of an integrated circuit package system500in an alternative embodiment of the present invention. The integrated circuit package system500includes a leadframe502having leads504with a leadfinger support with multi-studs506. The leadfinger support with multi-studs506may be formed by an etch process applied to the leads504. The leadfinger support with multi-studs506may be formed as protruding shape, such as more than one stud vertically protruding from the leads504. The leads504may also include a wetting surface508around the leadfinger support with multi-studs506.

The integrated circuit package system500also includes an integrated circuit die510having electrical interconnects512. The electrical interconnects512may be formed on the integrated circuit die510and flowed on the leadfinger support with multi-studs506providing electrical connectivity between the integrated circuit die510and the leadframe502.

The leadfinger support with multi-studs506provides control for a collapse level or height of the electrical interconnects512on the leads504. The wetting surface508, such as a recess, provides a physical resistance to the wetting or spread distance of the electrical interconnects512. The control of the collapse level and the spread distance of the electrical interconnects512provide a substantially controlled position of the integrated circuit die510along both the horizontal plane and vertical axes. It has been discovered that the substantially controlled position of the integrated circuit die510provides for an optional die attach paddle (not shown). The substantially controlled position of the integrated circuit die510also provides reduced stress and improved spacing for post-connection operations such as encapsulation or cleaning.

The integrated circuit package system500may also include an encapsulant514. The encapsulant514covers and protects the integrated circuit die510and the leadframe502. An encapsulating process such as molding, bonding or sealing may be used to apply the encapsulant514. The encapsulating process applies the encapsulant514over the integrated circuit die510, the electrical interconnects512, the leadframe502, the leads504, the leadfinger support with multi-studs506and the wetting surface508. The encapsulant514may conform to the integrated circuit die510and the leadframe502, although it is understood that the encapsulant may cover the integrated circuit die510and the leadframe502with other encapsulating processes.

Referring now toFIG. 6, therein is shown an isometric view of the leads504having the leadfinger support with multi-studs506. The leads504also include the wetting surface508and external connections602. The external connections202provide electrical connectivity to an electronic system (not shown) at a next level of integration or hierarchy such as a printed circuit board. An inner tip of the leads504may be etched to a reduced height while leaving portions protruding to form the leadfinger support with multi-studs506. The reduced height of the inner tip of the leads504forms the wetting surface508. It has been discovered that the leads504electrically connect the integrated circuit die510ofFIG. 5to the electronic system while providing control for the collapse level and the spread distance of the electrical interconnects512.

The shape and size of the leadfinger support with multi-studs506and the wetting surface508of the leads504provide a predetermined extent for the collapse level and the spread distance. For illustrative purposes, the leadfinger support with multi-studs506is shown as two rectangular prisms, although it is understood that other shapes, number of shapes or sizes may be used.

Referring now toFIG. 7, therein is shown a cross-sectional view of the integrated circuit package system500in a die placement phase. The integrated circuit package system500includes the integrated circuit die510over the leadframe502. The integrated circuit die510and the leadframe502are substantially fixed in a predetermined position. The electrical interconnects512are formed on an active surface702of the integrated circuit die510. Each of the electrical interconnects512on the active surface702of the integrated circuit die510are substantially aligned to each of the leadfinger support with multi-studs506of the leadframe502.

A fixture (not shown) may hold the integrated circuit die510and the leadframe502substantially aligned in the horizontal plane. A wetting interface material (not shown) may be applied between the electrical interconnects512and the leadfinger support with multi-studs506. The wetting interface material may provide adhesion between the electrical interconnects512and the leadfinger support with multi-studs506. The fixture may allow vertical movement of the integrated circuit die510or the leadframe502, or the fixture may release the integrated circuit die510or the leadframe502for attachment.

Referring now toFIG. 8, therein is shown a cross-sectional view of the integrated circuit package system500in a die attachment phase. The integrated circuit package system500includes the integrated circuit die510mounted over the leadframe502. An attachment process, such as an attach reflow, provides flowing of the electrical interconnects512on the active surface702around the leadfinger support with multi-studs506. The attachment process may include a thermal or similar process providing a liquefying or partial liquefying of the electrical interconnects512. The electrical interconnects512in a liquid or partial liquid state flows around the leadfinger support with multi-studs506and over the wetting surface508of the leads504.

The flowing of the electrical interconnects512results in a collapse of the electrical interconnects512and a position of the integrated circuit die510at a collapse level802determined by the size and shape of the leadfinger support with multi-studs506. The flowing of the electrical interconnects512also results in the wetting of the electrical interconnects512over the wetting surface508to a spread distance804determined by the size and shape of the wetting surface508. Each of the electrical interconnects512may overlap one each of the leadfinger support with multi-studs506and the wetting surface508to an extent predetermined by the size and shape of the leadfinger support with multi-studs506and the wetting surface508.

Referring now toFIG. 9is a flow chart of an integrated circuit package system900for manufacturing the integrated circuit package system100in an embodiment of the present invention. The system900includes forming a leadframe having a lead with a leadfinger support providing control of the collapse level in a block902; and attaching an integrated circuit die with an electrical interconnect on the leadfinger support in a block904.

In greater detail, a method to fabricate the integrated circuit package system100, in an embodiment of the present invention, is performed as follows:1. Forming the leadframe having the lead with the leadfinger support of a predetermined height providing control of the collapse height and the wetting surface providing control of the spread distance. (FIG. 1)2. Forming an integrated circuit die with the active surface having the electrical interconnect. (FIG. 1)3. Aligning the electrical interconnect with the leadfinger support. (FIG. 3)4. Attaching the integrated circuit die on the leadframe at the predetermined collapse height and the spread distance. (FIG. 4)

It has been discovered that the present invention thus has numerous aspects.

An aspect is that the present invention provides controlled bump collapse. The leadfinger support provides control during wetting of the bumps. Without the leadfinger support, many factors affect the bump collapse making the resulting level or height difficult to maintain. The leadfinger support provides a predetermined level or height of the bump after wetting.

It has been discovered that the disclosed structure provides controlled bump spread. The leadfinger support provides control during wetting of the bumps. Without the leadfinger support, many factors affect the bump spread making the resulting distance or area difficult to maintain. The leadfinger support provides a resistance to the spread distance and area of the bump after wetting.

It has also been discovered that the disclosed structure eliminates the need for a die paddle. Without the leadfinger support, a die attach pad provides a substantially fixed location for the integrated circuit die. The integrated circuit die location is particularly critical for the level or height. The leadfinger support provides a predetermined level or height of the integrated circuit die after wetting.

Yet another discovery of the disclosed structure is that the manufacturing process is simplified. The bumps for the integrated circuit die may be manufactured with known technologies using efficient and economical manufacturing. The improvement to the leadframe can be implemented by adapting known technologies and is cost-effective and uncomplicated. The leadfinger support provides the required control with straightforward, efficient, and economical manufacturing.

Thus, it has been discovered that the integrated circuit package system with leadfinger support method and apparatus of the present invention furnish important and heretofore unknown and unavailable solutions, capabilities, and functional aspects. The resulting processes and configurations are straightforward, cost-effective, uncomplicated, highly versatile and effective, can be implemented by adapting known technologies, and are thus readily suited for efficient and economical manufacturing.