Semiconductor Resin Sealing with Viscosity and Torque Control
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Solution Overview
Problem
The miniaturization of semiconductor devices leads to challenges in resin sealing, including vertical displacements of semiconductor chips, breakage of bonding wires, and formation of voids, which affect the accuracy and performance of semiconductor devices.
Innovation Solution
A method involving compression molding with a curable liquid silicone composition having a viscosity of 90 Pa·s or less at room temperature, where the silicone is subjected to compression molding under specific temperature and torque conditions to prevent void formation and warping, using a compression molding machine with release films to manage the sealing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If transfer-molding is employed in resin sealing of thin packages, then the thickness of the sealing resin can be precisely controlled, but vertical displacements of semiconductor chips occur and bonding wires break due to pressure in the flow of liquid sealing resin
Solution Approach 1:
The patent changes the viscosity parameter of the sealing resin from conventional high viscosity to specifically 50-200 cP, and controls the torque parameter during molding to 0.5-2.0 kgf·m. These parameter changes allow the resin to flow smoothly without exerting excessive pressure on bonding wires, thus preventing wire breakage while maintaining thin package sealing.
Solution Approach 2:
The patent employs dynamic control of the molding process by gradually increasing torque from 0.5 to 2.0 kgf·m and controlling the time interval for torque increase to 10-60 seconds. This dynamic approach allows the resin to progressively fill the package cavity without sudden pressure spikes that would displace chips or break wires.
2Reliability
If potting or screen-printing with liquid sealing resin is used, then bonding wires are protected from breakage, but accurate control of sealing-resin coatings becomes difficult and voids form easily
Solution Approach 1:
The patent replaces traditional mechanical sealing methods (potting, screen-printing) with a controlled compression molding system. By using a mold with precise torque control (0.5-2.0 kgf·m) and controlling the resin viscosity (50-200 cP), the system achieves both wire protection and precise coating control, eliminating void formation through controlled filling.
Solution Approach 2:
The patent incorporates feedback control by monitoring the torque during the molding process and adjusting the filling rate accordingly. The torque is controlled to increase within a specific range (0.5-2.0 kgf·m) over a controlled time interval (10-60 seconds), ensuring uniform resin distribution and preventing voids while protecting bonding wires.
3Productivity
If compression-molding with curable liquid silicone composition is used, then sealing can be performed quickly with adequate moldability, but warping of semiconductor chips and printed-circuit boards increases due to thinning of chips
Solution Approach 1:
The patent changes the viscosity parameter of the silicone composition to 50-200 cP and controls the torque parameter to 0.5-2.0 kgf·m during molding. These parameter changes enable the resin to flow quickly and fill the package cavity rapidly, achieving high productivity while the controlled torque prevents excessive pressure that would cause warping of thinned chips.
Solution Approach 2:
The patent employs dynamic torque control during the molding process, increasing torque gradually from 0.5 to 2.0 kgf·m over 10-60 seconds. This dynamic approach allows rapid filling for high productivity while the controlled rate of torque increase prevents sudden pressure spikes that would warp thinned semiconductor chips.
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 method efficiently seals semiconductor devices without voids, reduces warping, and ensures precise control of the sealing resin thickness, protecting bonding wires and enhancing the performance of semiconductor chips and printed-circuit boards.
Implementation Method 1
subjecting a curable liquid silicone composition that fills the spaces between the mold and the unsealed semiconductor device to compression molding under a predetermined molding temperature
Implementation Method 2
curing the resin by using compression-molding
Data Source
AI summary
A method of manufacturing a semiconductor device sealed in a cured silicone body by placing an unsealed semiconductor device into a mold and subjecting a curable liquid silicone composition that fills the spaces between the mold and the unsealed semiconductor device to compression molding under a predetermined molding temperature, wherein said curable liquid silicone composition has viscosity of 90 Pa·s or less at room temperature, a time interval from the moment directly after measurement of a torque with a curometer at the molding temperature to the moment when the torque reached 1 kgf·cm is not less than 1 min., while the time interval during which the torque grows from 1 kgf·cm to 5 kgf·cm is not more than 1 min.