Segmented Via Hole Fabrication for Thick Insulating Layers
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Solution Overview
Problem
The existing through molding via (TMV) technology for electronic packages faces challenges in increasing the thickness of the insulating layer, which affects the aspect ratio of via holes, leading to issues with fine pitch requirements, incomplete copper plating, and residue accumulation, thereby impacting process yield and fabrication cost.
Innovation Solution
The method involves forming through holes in two steps, with controlled aspect ratios for the first and second via holes, allowing for increased insulating layer thickness without widening the holes, enabling effective plating and residue removal, thus meeting fine pitch requirements and improving yield and cost efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the insulating layer is increased to improve reliability, then the aspect ratio of through holes must be increased, but this causes incomplete copper plating and residue accumulation, adversely affecting process yield
Solution Approach 1:
The through hole formation process is segmented into two separate steps: first forming a via hole from the first surface to a first depth, then forming a second via hole from the second surface to a second depth, where the two via holes meet to complete the through hole. This segmentation allows each via hole to have a manageable aspect ratio that enables complete copper plating, while the combined structure achieves the required insulating layer thickness for reliability.
2Reliability
If the thickness of the insulating layer is increased to meet fine pitch requirements, then the width of through holes must be increased to maintain aspect ratio, but this compromises fine pitch requirements
Solution Approach 1:
By dividing the through hole formation into two separate via holes formed from opposite surfaces, each via hole maintains a small width suitable for fine pitch requirements while achieving the necessary depth through the increased insulating layer thickness. The segmentation eliminates the need to increase via hole width to maintain aspect ratio.
3Reliability
If the depth of through holes is increased to accommodate thicker insulating layers, then residue removal becomes difficult, but residue adversely affects electrical transmission performance
Solution Approach 1:
The via hole formation is segmented into two shallower holes from opposite surfaces, each with reduced depth compared to a single through hole. This segmentation makes residue removal easier for each individual via hole while maintaining the electrical transmission performance through the complete through-hole structure.
Solution Approach 2:
Residue removal is performed as a preliminary action after forming each via hole but before forming the complete through hole structure. This preliminary cleanup ensures that residue does not adversely affect the subsequent copper plating or electrical transmission performance.
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 allows for increased insulating layer thickness without compromising aspect ratios, ensuring complete plating and residue removal, thereby enhancing process yield and reducing fabrication costs while maintaining electrical transmission performance.
Implementation Method 1
forming via holes on a surface of an encapsulant by laser drilling
Implementation Method 2
a copper electroplating process is performed to form a plurality of conductive posts 12 in the through holes 110
Data Source
AI summary
A method for fabricating an electronic package is provided, which includes the steps of: providing an insulating layer having at least an electronic element embedded therein; forming at least a first via hole on one side of the insulating layer; forming a first conductor in the first via hole of the insulating layer; forming on the insulating layer a first circuit structure electrically connected to the electronic element and the first conductor; and forming a second via hole on the other side of the insulating layer, wherein the second via hole communicates with the first via hole. As such, the second via hole and the first via hole constitute a through hole. Since the through hole is fabricated through two steps, the aspect ratio (depth/width) of the through hole can be adjusted according to the practical need so as to improve the process yield.