ELECTRONIC ASSEMBLIES AND SYSTEMS WITH FILLED NO-FLOW UNDERFILL
First Claim
1. An electronic assembly comprising:
- at least one integrated circuit package having a plurality of terminals;
a substrate having a plurality of pads coupled to the plurality of terminals via a corresponding plurality of connections;
a hardened underfill encapsulating the terminals, pads, and connections; and
a plurality of particles in the underfill, wherein some of the particles are of such size and shape as to potentially inhibit suitable physical and electrical contact between corresponding terminals and pads if such particles remained in the connections, and wherein one or more particles are embedded in one of the terminals, in its corresponding pad, or in both the one terminal and its corresponding pad, but such one or more particles are of such size and shape that they do not prevent adequate physical and electrical contact between corresponding terminals and pads.
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Accused Products
Abstract
High yield, high reliability, flip-chip integrated circuit (IC) packages are achieved utilizing a combination of heat and pressure to bond flip-chip die and to cure no-flow underfill material. The underfill comprises a filler or low coefficient of thermal expansion (CTE) material to decrease CTE of the cured underfill. The filler material can be selected from the group comprising silica, silicon oxide, silicon dioxide, silicon nitride, aluminum oxide, aluminum nitride, or a mixture thereof. The filler material may also increase the viscosity of the uncured underfill and/or increase the modulus of elasticity of the cured underfill. In some method embodiments, a thermocompression bonder is used to simultaneously provide solder bump reflow and underfill curing. Application of various methods to a component package, an electronic assembly, and an electronic system are also described.
21 Citations
17 Claims
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1. An electronic assembly comprising:
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at least one integrated circuit package having a plurality of terminals;
a substrate having a plurality of pads coupled to the plurality of terminals via a corresponding plurality of connections;
a hardened underfill encapsulating the terminals, pads, and connections; and
a plurality of particles in the underfill, wherein some of the particles are of such size and shape as to potentially inhibit suitable physical and electrical contact between corresponding terminals and pads if such particles remained in the connections, and wherein one or more particles are embedded in one of the terminals, in its corresponding pad, or in both the one terminal and its corresponding pad, but such one or more particles are of such size and shape that they do not prevent adequate physical and electrical contact between corresponding terminals and pads. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An electronic assembly comprising:
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at least one integrated circuit package having a plurality of terminals;
a substrate having a plurality of pads to be coupled to the plurality of terminals via a corresponding plurality of connections; and
an unhardened underfill covering the terminals and pads;
wherein the underfill, when heated, is to harden;
wherein the underfill, when hardened, is to have a coefficient of thermal expansion;
wherein the underfill comprises a plurality of particles to reduce the coefficient of thermal expansion;
wherein the particles are of such size and shape as to potentially inhibit suitable connections between corresponding terminals and pads;
wherein the terminals are to physically contact the pads, and wherein most but not all of the particles are to be removed from between the terminals and the pads, when suitable pressure is applied to the package and/or the substrate, with one or more particles being embedded in one of the terminals, in its corresponding pad, or in both the one terminal and its corresponding pad without preventing adequate physical and electrical contact; and
wherein the underfill further comprises a fluxing agent to clean the terminals and pads when suitable heat is applied to the electronic assembly to connect the terminals and pads. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An electronic system comprising:
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a bus coupling components in the electronic system;
a display coupled to the bus;
external memory coupled to the bus; and
a processor coupled to the bus and having an electronic assembly including at least one integrated circuit package fabricated by;
depositing an underfill material over a plurality of pads in a component-mounting area of a substrate, the underfill material comprising a filler material containing particles;
placing a component on the component-mounting area, such that terminals of the component are aligned with corresponding pads and substantially enveloped in the underfill material, the particles potentially inhibiting a suitable connection between corresponding terminals and pads unless the particles are substantially removed;
applying suitable pressure to cause the terminals to physically contact the pads and to remove most but not all potentially inhibiting particles from between corresponding terminals and pads, with one or more particles being embedded in one of the terminals, in its corresponding pad, or in both the one terminal and its corresponding pad without preventing adequate physical and electrical contact; and
applying suitable heat to melt solder situated between the terminals and pads, which when cooled results in an electrical and mechanical connection between corresponding terminals and pads. - View Dependent Claims (16, 17)
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Specification