Chip Package Cavity Protection During Encapsulation
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Solution Overview
Problem
During chip packaging, cavities in micro-electro-mechanical chips can be unintentionally filled with encapsulation material, damaging the mechanically fragile structures that delimit them, which are often sensitive and prone to damage.
Innovation Solution
A method involving temporary covering or filling of cavities with a suitable adhesive or solid filling material to protect them from unwanted material intrusion, followed by selective removal and re-exposure to allow access and processing, using techniques like grinding or etching to preserve the integrity of the fragile structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cavity is left open during packaging, then access to the cavity is maintained, but the cavity may be unintentionally filled with encapsulation material and the fragile structure may be damaged
Solution Approach 1:
A cover is placed over the cavity opening before the packaging process to prevent encapsulation material from entering the cavity. This preliminary protective action ensures the fragile structure inside the cavity is not damaged during subsequent packaging operations, while still allowing the packaging process to proceed normally.
Solution Approach 2:
The cover acts as an intermediary element between the cavity and the encapsulation material. It physically separates the fragile structure inside the cavity from the incoming encapsulation material, preventing direct contact and potential damage while allowing the packaging process to continue uninterrupted.
2Reliability
If the cavity is covered temporarily, then damage from encapsulation material is prevented, but additional processing steps are required
Solution Approach 1:
The cover is temporarily placed on the cavity before packaging and then removed afterward. This preliminary protective measure prevents damage during the critical packaging phase, and the temporary nature of the cover means it can be easily removed without requiring complex additional processing steps.
Solution Approach 2:
The cover is used temporarily during the packaging process and then discarded or removed. This approach allows the protective function to be performed only when needed, avoiding permanent additions to the device structure and minimizing the number of additional processing steps required.
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 stabilizes the wafer, prevents damage to the mechanically fragile structures, and allows for precise re-exposure and further processing of the cavities, enhancing the yield and integrity of the chip package.
Implementation Method 1
The plurality of chips is temporarily bonded to a temporary carrier with the mechanically fragile structure facing the temporary carrier
Implementation Method 2
followed by selective removal and re-exposure to ensure accurate packaging and access, using techniques like grinding and etching
Implementation Method 3
using techniques like grinding and etching to maintain structural integrity
Data Source
AI summary
A method of producing a chip package is described. A plurality of chips is provided on a first wafer. Each chip has a cavity which opens to a first main face of the chip. The cavities are filled or covered temporarily. The chips are then singulated. The singulated chips are embedded in an encapsulation material, and then the cavities are re-exposed.