Multi-Temperature Molding for Integrated Circuit Packages
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Solution Overview
Problem
The molding process of large integrated circuit components often traps air bubbles due to the high viscosity of the molding compound, leading to stress and warpage issues, especially when subjected to varying atmospheric pressures or vacuum environments, which can cause damage to thin wafers.
Innovation Solution
A multi-temperature molding process is employed, where the molding compound is initially maintained at a temperature below its gel point to facilitate easy flow and minimize air bubble formation, followed by a temperature increase above the gel point for curing, using a mold with integrated heating and cooling elements to control temperature profiles and ensure complete spreading and solidification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the molding compound is kept at high viscosity to maintain structural integrity, then the compound can support large integrated circuit components, but air bubbles become trapped and cannot flow to all regions
Solution Approach 1:
The patent applies parameter changes by controlling the temperature of the molding compound throughout the molding process. The compound is heated to a temperature range (e.g., above its glass transition temperature or melting point) that reduces its viscosity, enabling it to flow completely and eliminate air bubbles. After molding, the temperature is reduced to restore structural integrity. This temperature parameter control resolves the contradiction between maintaining low viscosity for complete filling and high viscosity for structural support.
2Manufacturing precision
If the molding compound flows easily to reach all regions, then complete molding is achieved, but air bubbles are more likely to be trapped due to high viscosity
Solution Approach 1:
The patent uses parameter changes by adjusting the temperature of the molding compound to an optimal range that balances flowability and air bubble elimination. At this elevated temperature, the compound has reduced viscosity that allows complete flow over large integrated circuit components while also enabling air bubbles to rise and escape. The temperature is then reduced after molding to solidify the compound without trapping bubbles.
3Adaptability or versatility
If atmospheric pressure changes occur during or after molding, then vacuum processes can be performed, but stresses are generated that cause thin wafers to break
Solution Approach 1:
The patent applies parameter changes by controlling the temperature and pressure parameters during the molding process. The molding is performed at elevated temperature and pressure to ensure complete filling and bubble elimination. After molding, the compound is cooled and pressurized to stabilize the structure before vacuum processes. This parameter control creates a robust molded structure that can withstand subsequent pressure changes without causing wafer breakage.
4Productivity
If the molding compound is cooled rapidly to solidify, then production time is reduced, but warpage increases in the molded packages
Solution Approach 1:
The patent applies preliminary action by performing complete air bubble elimination and structural stabilization during the molding process itself, before the cooling and solidification stages. The compound is molded at elevated temperature to ensure complete filling and bubble removal, and the mold is designed to maintain pressure and temperature control throughout the process. This preliminary action ensures that when rapid cooling occurs, the structure is already stable and uniform, minimizing warpage despite the fast cooling rate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the likelihood of air bubble entrapment, minimizes stress and warpage in molded packages, and enhances the reliability of integrated circuit components by ensuring a bubble-free and uniformly solidified molding compound.
Implementation Method 1
the molding compound is initially maintained at a temperature below its gel point to facilitate easy flow
Implementation Method 2
followed by a temperature increase above the gel point for curing
Implementation Method 3
using a mold with integrated heating and cooling elements to control temperature profiles
Data Source
AI summary
A method includes molding a polymer onto a package component. The step of molding includes a first molding stage performed at a first temperature, and a second molding stage performed at a second temperature different from the first temperature.