IC Package Adhesive Crown Structure to Prevent Glue Overflow
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Solution Overview
Problem
In WB-BGA integrated circuit packages, excess glue can rise along the vertical edges of the chip, contaminating contact pads and causing stress on dielectric layers, while reducing glue quantity leads to insufficient coverage and potential cracks.
Innovation Solution
A dual-adhesive interface is used, where a crown of one adhesive material on the periphery of the chip's lower face houses a second adhesive material, preventing glue overflow and ensuring adequate coverage and adhesion, with the second material covering at least 80% to 90% of the chip's surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single adhesive material is used to fasten the chip onto the carrier substrate, then the manufacturing process is simple, but the adhesive either overflows and contaminates contact pads or provides insufficient coverage causing cracks
Solution Approach 1:
The adhesive interface is segmented into two distinct adhesive materials: a first adhesive material applied at the periphery of the chip, and a second adhesive material filling the internal housing. This segmentation allows each material to perform its specific function - the first material prevents overflow and defines the bonding interface, while the second material provides comprehensive coverage for mechanical strength and crack prevention.
Solution Approach 2:
Different adhesive materials are applied to different locations of the chip's lower face. The first adhesive material is applied at the periphery where overflow control is critical, while the second adhesive material fills the central housing area where coverage and adhesion strength are paramount. This local quality approach optimizes the adhesive performance for each specific region's requirements.
2Reliability
If the quantity of adhesive material is increased to ensure adequate coverage, then crack risk is reduced, but glue overflow and contamination of contact pads occurs
Solution Approach 1:
The first adhesive material is applied in advance at the periphery of the chip, creating a containment structure before the second adhesive material is applied. This preliminary action defines the boundaries of the adhesive interface and prevents the second material from overflowing onto the contact pads, while still allowing sufficient quantity of adhesive to be applied for complete coverage.
Solution Approach 2:
The first adhesive material acts as an intermediary element between the chip and the second adhesive material. It serves as a barrier that controls the spread of the second adhesive material, preventing contamination of contact pads while allowing the second material to provide adequate coverage in the housing area.
3Strength
If adhesive material is applied to cover the entire chip surface, then strong adhesion is achieved, but stress on dielectric layers increases due to overflow
Solution Approach 1:
The adhesive application is segmented into peripheral and central zones with different material properties. The first adhesive material at the periphery provides adhesion strength without excessive overflow, while the second adhesive material in the central housing provides additional bonding strength. This segmentation maintains strong overall adhesion while controlling stress on dielectric layers by preventing unnecessary overflow.
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 configuration effectively prevents glue overflow, minimizes stress on dielectric layers, and reduces the risk of cracks while maintaining strong adhesion between the chip and substrate.
Implementation Method 1
a first adhesive material forms a crown allowing on the one hand to control the thickness between the chip and the carrier substrate well, and on the other hand to house a second adhesive material which because of the presence of this crown does not rise on the vertical edges of the chip
Implementation Method 2
at least one electronic chip having a first face, typically the lower face, fastened onto a first face, typically the upper face, of a carrier substrate by an adhesive interface
Data Source
AI summary
An integrated circuit package includes at least one electronic chip having a first face fastened onto a first face of a carrier substrate by an adhesive interface. The adhesive interface includes a crown formed of a first adhesive material that is fastened on the periphery of the first face of the electronic chip. The crown defining an internal housing. A second adhesive material, different than the first material, is deposited in the internal housing.