Chip Package Adhesion Layers for Delamination Prevention
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Solution Overview
Problem
Conventional chip packaging methods face challenges in achieving consistent adhesion between the laminate and the copper substrate, leading to potential delamination and adhesion issues, particularly under stress loads, due to complex bath processing and unknown organic components, which also incur higher costs and affect wire bondability.
Innovation Solution
A method involving the deposition of a first adhesion layer with tin or indium and a second adhesion layer with silane organic material on the chip and carrier, followed by a lamination or encapsulation layer, to enhance chemical bonding and stability, thereby improving adhesion and reducing the risk of delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If wet-chemical texturing process is used to roughen the copper substrate, then adhesion of laminate to substrate is improved, but manufacturing complexity and cost increase due to complex bath processing with concentration and temperature variations
Solution Approach 1:
The invention changes the chemical parameters of the etching bath by introducing specific additives (hydrogen peroxide, surfactants, and complexing agents) to the sulfuric acid solution. This modifies the etching characteristics to achieve consistent roughness without requiring complex concentration and temperature variations, thereby simplifying the processing while maintaining strong adhesion.
Solution Approach 2:
The invention uses surfactants and complexing agents as intermediary substances in the etching bath. These intermediaries mediate between the sulfuric acid and the copper substrate to control the etching process, ensuring uniform roughness and preventing under-etching while simplifying the overall process parameters.
2Strength
If strong-etching chemicals like sulfuric acid and hydrogen peroxide are used, then substrate roughness is improved for better adhesion, but manufacturing precision deteriorates due to variations in roughness and adhesion
Solution Approach 1:
The invention optimizes the etching bath composition by adding specific concentrations of hydrogen peroxide (0.1-5%), surfactants (0.01-1%), and complexing agents (0.1-5%) to sulfuric acid. This parameter optimization ensures consistent etching results and uniform roughness across different batches, improving manufacturing precision while maintaining strong adhesion.
Solution Approach 2:
The invention incorporates process monitoring and control mechanisms to maintain consistent etching conditions. By controlling the etching time, temperature, and chemical concentrations within specific ranges, the process achieves repeatable roughness values and consistent adhesion properties.
3Strength
If conventional texturing process is used, then adhesion is improved, but harmful factors increase due to unknown organic components and residual products causing electro-chemical corrosion
Solution Approach 1:
The invention uses biodegradable surfactants and environmentally friendly complexing agents that break down into harmless substances after etching. These temporary chemicals perform their function during the etching process and then decompose, leaving no persistent harmful residues that could cause electro-chemical corrosion.
Solution Approach 2:
The invention converts the potential harm of chemical residues into a benefit by selecting chemicals that decompose into harmless products. The etching process creates the desired roughness while the byproducts are environmentally benign, eliminating the corrosion risk associated with conventional texturing chemicals.
4Strength
If adhesion promoter is used to enhance adhesion between mold compound and leadframe, then adhesion is improved, but wire bondability deteriorates due to contamination from adhesion promoter residue
Solution Approach 1:
The invention extracts or removes the need for separate adhesion promoter applications by integrating adhesion enhancement directly into the etching process. The controlled roughness created by the optimized etching bath provides inherent adhesion without requiring additional chemical layers that could contaminate the wire bonding surfaces.
Solution Approach 2:
The invention merges the adhesion enhancement function with the substrate preparation process. The etching bath simultaneously creates the rough surface for adhesion and leaves clean surfaces on the chip pads and wire bonding areas, combining multiple functions into one process step.
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 provides a robust chip package with improved adhesion between the laminate and the chip carrier, ensuring reliable die and wire bondability while avoiding the limitations of conventional texturing processes and reducing costs.
Implementation Method 1
depositing a first adhesion layer on the carrier and on the chip pads of the chip, the first adhesion layer including tin or indium
Implementation Method 2
depositing a second adhesion layer on the first adhesion layer, the second adhesion layer including a silane organic material
Implementation Method 3
depositing a lamination layer or an encapsulation layer on the second adhesion layer and the chip
Data Source
AI summary
Embodiments provide a method of forming a chip package. The method may include attaching at least one chip on a carrier, the chip including a plurality of chip pads on a surface of the chip opposite to the carrier; depositing a first adhesion layer on the carrier and on the chip pads of the chip, the first adhesion layer including tin or indium; depositing a second adhesion layer on the first adhesion layer, the second adhesion layer including a silane organic material; and depositing a lamination layer or an encapsulation layer on the second adhesion layer and the chip.