Flip Chip Substrate Segmented Dielectric Layers for Presolder Uniformity
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Solution Overview
Problem
The presolder printing process in flip chip ball grid array (FCBGA) packages faces challenges due to uneven solder mask surfaces and substrate warpage, leading to inconsistent ball sizes, quantities, and low process yield, especially with varying sizes and densities of conductive pads on the substrate.
Innovation Solution
A flip chip substrate with two dielectric layers, where a first insulating layer covers the chip conductive zone with patterned openings exposing the conductive pads, and a second insulating layer covers the passive component conductive zone with similar openings, allowing for uniform contact and improved presolder printing quality, along with conductive posts to increase connection area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single solder mask covers the whole substrate plate, then the substrate can be manufactured, but the solder mask surface becomes uneven and the substrate plate warps, leading to poor presolder printing quality
Solution Approach 1:
The substrate plate is divided into multiple independent substrates, each with its own solder mask layer. This segmentation allows each substrate to be manufactured and processed separately, preventing the warping and unevenness that occurs when a single large solder mask covers the entire substrate plate. The presolder printing quality is improved because each individual substrate maintains a flat, uniform surface.
Solution Approach 2:
Each substrate is equipped with a solder mask layer that is specifically tailored to its local requirements, with patterned openings positioned precisely over the conductive pads. This local customization ensures that the solder mask surface remains even and flat across each substrate, enabling high-quality presolder printing without the warping issues that affect large-area uniform masks.
2Adaptability or versatility
If conductive pads of various sizes and densities are formed on the substrate, then the circuit functionality is achieved, but the solder mask becomes uneven and presolder printing quality cannot be controlled
Solution Approach 1:
The substrate plate is segmented into multiple individual substrates, each handling its own conductive pads of various sizes and densities. This segmentation isolates the complexity of different pad configurations to individual substrates, allowing each to maintain a uniform solder mask surface despite having different pad patterns, thereby ensuring consistent presolder printing quality across all substrates.
Solution Approach 2:
Each substrate receives a customized solder mask layer with patterned openings that precisely match its specific conductive pad configuration. This local adaptation allows the substrate to accommodate various pad sizes and densities while maintaining an even solder mask surface, ensuring that presolder printing quality remains controlled and consistent despite the diversity in pad arrangements.
3Productivity
If the solder mask surface is uneven or the substrate plate warps, then manufacturing is possible, but different ball sizes, different quantities of presolders, and low process yield occur
Solution Approach 1:
By dividing the substrate plate into multiple individual substrates, each with its own solder mask layer, the system eliminates the warping and unevenness that plague large-area substrates. This segmentation ensures that each substrate maintains a flat, uniform surface, enabling consistent presolder application with uniform ball sizes and quantities, thereby significantly improving process yield and reducing defects.
Solution Approach 2:
Each substrate is provided with a locally optimized solder mask layer that ensures an even surface across the entire substrate area, regardless of the conductive pad configuration. This local quality control prevents the solder mask unevenness and substrate warping that lead to variable presolder characteristics, ensuring uniform presolder application and high process yield.
Data Source
AI summary
A flip chip substrate comprises a substrate that is defined a chip connect zone which has a plurality of first conductive pads and passive component connect zone which has at least a second conductive pads. A first patterned insulating layer within opening that covers on the chip connect zone and exposed to the first conductive pads, a second patterned insulating layer within opening that covers on the passive component connect zone and exposed to the second conductive pads, to enhance the reliability of chip package.