Packaged integrated circuit including heat slug having an exposed surface
First Claim
1. A structure, comprising:
- a semiconductor die;
a leadframe comprised of a die attach pad and a plurality of electrically conductive leads, wherein;
the leads are formed around a circumference of and are electrically isolated from the die attach pad; and
the die attach pad has first and second surfaces, the first surface attached to a surface of the semiconductor die, the second surface being opposite the first surface;
a heat slug including;
a base section having a first base surface and a second base surface opposite the first base surface, a plurality of fins formed on a surface perpendicular to the first and second base surfaces at spaced apart locations around the circumference of the base section;
a first raised section formed on the first base surface having a die attach pad attachment surface parallel to and raised with respect to the first base surface, the die attach pad attachment surface attached to the second surface of the die attach pad; and
a second raised section formed on the second base surface having a primary heat transfer surface parallel to and raised with respect to the second base surface, a surface of the second raised section that is perpendicular to the primary heat transfer surface being roughened; and
insulating material encapsulating the semiconductor die, leadframe and heat slug such that the primary heat transfer surface of the heat slug is exposed to the exterior of the insulating material and such that the insulating material interlocks with the roughened surface of the second raised section;
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Accused Products
Abstract
A low cost electronic device package having greatly improved heat dissipation capability. The package includes a heat slug, preferably formed from oxygen-free high-conductivity copper, that has a surface exposed outside the package. A simplified and inexpensive manufacturing method is described using a "drop in" technique. Using this technique, the size and shape of the heat slug is dependent only on the size and shape of the mold cavity; the package may have any number of leads and any size die. The heat slug is preferably formed with fins around its circumference so that the slug is self-aligning when it is dropped into the mold cavity. Preferably, slots are formed through the heat slug to provide improved encapsulant flow during the encapsulation process and interlocking between slug and encapsulant in the finished package. The heat slug may have at least one toughened surface on its circumference that interlocks with the encapsulant, helping to hold the heat slug in place and preventing contaminants from migrating to the interior of the package. Formation of encapsulant bleed or flash on the exposed heat slug surface are prevented by providing a dimensional mismatch between the heat slug and leadframe, and the corresponding height of the mold cavity that causes the leadframe tie bars to force the heat slug exposed surface against the mold cavity surface, producing a tight seal so that encapsulant is prevented from coming between those two surfaces.
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Citations
16 Claims
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1. A structure, comprising:
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a semiconductor die; a leadframe comprised of a die attach pad and a plurality of electrically conductive leads, wherein; the leads are formed around a circumference of and are electrically isolated from the die attach pad; and the die attach pad has first and second surfaces, the first surface attached to a surface of the semiconductor die, the second surface being opposite the first surface;
a heat slug including;a base section having a first base surface and a second base surface opposite the first base surface, a plurality of fins formed on a surface perpendicular to the first and second base surfaces at spaced apart locations around the circumference of the base section; a first raised section formed on the first base surface having a die attach pad attachment surface parallel to and raised with respect to the first base surface, the die attach pad attachment surface attached to the second surface of the die attach pad; and a second raised section formed on the second base surface having a primary heat transfer surface parallel to and raised with respect to the second base surface, a surface of the second raised section that is perpendicular to the primary heat transfer surface being roughened; and insulating material encapsulating the semiconductor die, leadframe and heat slug such that the primary heat transfer surface of the heat slug is exposed to the exterior of the insulating material and such that the insulating material interlocks with the roughened surface of the second raised section; - View Dependent Claims (2, 3, 4, 5, 6)
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7. A structure, comprising:
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a semiconductor die, the die having a plurality of die contact pads located on a first surface of the die and a second surface opposite the first surface; a leadframe comprised of a die attach pad, a plurality of tie bars and a plurality of electrically conductive leads, wherein; the tie bars and the leads are formed around a circumference of the die attach pad; an inner end of each tie bar is connected to the die attach pad; an inner end of each lead is adjacent to and electrically isolated from the die attach pad; and the die attach pad has first and second surfaces, the first surface attached to the second surface of the semiconductor die, the second surface being opposite the first surface; a plurality of electrically conductive bond wires, each bond wire connecting a die contact pad to the inner end of one of the leads; a heat slug including; a base section having a first base surface and a second base surface Opposite the first base surface, a plurality of fins formed on a surface perpendicular to the first and second base surfaces at spaced apart locations around the circumference of the base section; a first raised section formed on the first base surface having a die attach pad attachment surface parallel to and raised with respect to the first base surface, the die attach pad attachment surface attached to the second surface of the die attach pad; and a second raised section formed on the second base surface having a primary heat transfer surface parallel to and raised with respect to the second base surface, a surface of the second raised section that is perpendicular to the primary heat transfer surface being roughened; and an insulating material encapsulating the semiconductor die, leadframe, bond wires and heat slug such that the primary heat transfer surface of the heat slug is exposed to the exterior of the insulating material, and such that the insulating material interlocks with the roughened surface of the second raised section. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A structure, comprising:
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a semiconductor die, the die having a plurality of die contact pads located on a first surface of the die and a second surface opposite the first surface; a leadframe comprised of a die attach pad, a plurality of tie bars and a plurality of electrically conductive leads, wherein; the tie bars and the leads are formed around a circumference of the die attach pad; an inner end of each tie bar is connected to the die attach pad; an inner end of each lead is adjacent to and electrically isolated from the die attach pad; and the die attach pad has first and second surfaces, the first surface attached to the second surface of the semiconductor die; a plurality of electrically conductive bond wires, each bond wire connecting a die contact pad to the inner end of one of the leads; an oxygen-free high-conductivity copper heat slug comprising; a base section having a first base surface and a second base surface opposite the first base surface; a first raised section formed on the first base surface having a die attach pad attachment surface parallel to and raised with respect to the first base surface, the die attach pad attachment surface attached to the second surface of the die attach pad; a second raised section formed on the second base surface having a primary heat transfer surface parallel to and raised with respect to the second base surface; at least one surface of the second raised section that is perpendicular to the primary heat transfer surface being roughened; at least one slot formed through the base section of the heat slug to extend from the first base surface to the second base surface; and a plurality of fins formed on a surface perpendicular to the first and second base surfaces at spaced apart locations around the circumference of the base section; and insulating material encapsulating the semiconductor die, leadframe, bond wires and heat slug such that the primary heat transfer surface of the heat slug is exposed to the exterior of the insulating material, and such that the insulating material interlocks with the roughened surface of the second raised section.
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14. A heat slug, comprising:
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a base section having a first base surface and a second base surface opposite the first base surface, a plurality of fins formed on a surface perpendicular to the first and second base surfaces at spaced apart locations around the circumference of the base section; a first raised section formed on the first base surface having a die attach pad attachment surface parallel to and raised above the first base surface; and a second raised section formed on the second base surface and having a primary heat transfer surface parallel to and raised above the second base surface, a surface of the second raised section that is perpendicular to the primary heat transfer surface being roughened. - View Dependent Claims (15, 16)
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Specification