Electronic Package Protective Layer for Solder Wetting
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Solution Overview
Problem
Conventional semiconductor packages face issues with heat accumulation due to low thermal conductivity of dielectric materials like polyimide, leading to solder non-wetting and adhesion problems during the separation process.
Innovation Solution
Employing an epoxy molding compound with high thermal conductivity as a protective layer to facilitate heat transfer and prevent solder non-wetting, and using a thermosetting epoxy molding compound that solidifies to avoid adhesion issues during separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dielectric layer made of polyimide material is formed on the electronic body to cover the conductors, then the conductors are protected, but heat energy accumulates in the dielectric layer during heating process and cannot be effectively transmitted to the solder material, resulting in solder non-wetting
Solution Approach 1:
The patent changes the material parameter of the protective layer from polyimide (low thermal conductivity) to epoxy molding compound (high thermal conductivity). This parameter change enables effective heat transmission from the heating source through the protective layer to the solder material, ensuring proper solder wetting while maintaining conductor protection.
Solution Approach 2:
The patent employs an epoxy molding compound that combines high thermal conductivity with protective properties. This composite material approach allows the protective layer to simultaneously provide mechanical protection to conductors and efficient thermal conduction pathway to the solder material, resolving the contradiction between protection and heat transfer.
2Ease of operation
If a dielectric layer made of polyimide material is used during the cooling process, then the electronic body is protected, but the dielectric layer remains in a semi-soluble fluid state with certain viscosity, causing the suction jig to adhere to the electronic structure and detach from the removing device
Solution Approach 1:
The patent utilizes the temperature-dependent parameter change of epoxy molding compound. During cooling, the epoxy molding compound transitions from a viscous semi-soluble state to a solid state, changing its physical properties. This parameter change ensures the material is easy to separate from the suction jig when solidified, while still providing protection during the process.
Solution Approach 2:
The patent exploits the phase transition of epoxy molding compound from liquid/semi-soluble state during heating to solid state during cooling. This phase transition enables the protective layer to be easily separated from the suction jig after solidification, preventing adhesion issues and ensuring smooth removal from the device.
3Ease of manufacture
If conventional polyimide material is used as the dielectric layer, then the manufacturing process is simple, but the thermal conductivity is low (less than 1 W/mK), leading to heat accumulation and solder non-wetting
Solution Approach 1:
The patent changes the thermal conductivity parameter of the protective layer material from low (polyimide <1 W/mK) to high (epoxy molding compound). This parameter change maintains manufacturing simplicity while dramatically improving heat transmission capability, ensuring reliable solder joint quality without complicating the manufacturing process.
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
Effective heat transfer to melt solder materials and prevent non-wetting, along with preventing the suction jig from adhering to the electronic structure during separation, enhancing the manufacturing process efficiency.
Implementation Method 1
the thermal conductivity of the PI material is relatively low (that is, less than 1 W/mK), heat energy will accumulate in the dielectric layer 11b made of the PI material during the heating process and cannot be effectively transmitted to the solder material 12c
Implementation Method 2
since the dielectric layer 11b made of the PI material still in a semi-soluble fluid state of the B stage during the cooling process, the dielectric layer 11b still has a certain viscosity
Data Source
AI summary
An electronic structure is provided, in which a plurality of conductors are disposed on one surface of an electronic body, an epoxy molding compound is used as a protective layer to encapsulate the plurality of conductors, a circuit portion is bonded onto the other surface of the electronic body, and a plurality of external bumps and solder material are formed on the circuit portion. Therefore, with the design of the protective layer, heat energy can be effectively transferred from the protective layer to the solder material below during a process of heating the electronic structure so as to avoid a problem of non-wetting of the solder material.