Protrusion Bump Pads for Bond-on-Trace Probe Testing
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Solution Overview
Problem
In Bond-on-Trace (BoT) processing, the trace pitch is often less than the bond pad pitch, leading to solder bonds inadvertently bridging connections with adjacent traces, making probe testing challenging due to the small trace diameter being below the diameter of common testing probes.
Innovation Solution
A substrate with conductive pillars extending through it, featuring protrusion bump pads on a first subset and recessed traces on a second subset, allowing for improved spacing and testing accessibility by forming protrusion bump pads over some conductive pillars and recessing others within the substrate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the trace pitch is reduced to increase the number of connections, then the connection density is improved, but the probe testing becomes challenging due to trace diameter being below the diameter of common testing probes
Solution Approach 1:
The invention segments the conductive structures into two distinct types: protrusion bump pads that extend above the substrate surface for easy probe access, and recessed traces that remain below the surface to prevent accidental contact. This segmentation allows probes to easily access bonding points while maintaining high trace density underneath.
Solution Approach 2:
The invention transitions from a two-dimensional planar arrangement to a three-dimensional structure by creating protrusions and recesses in the Z-dimension. The bump pads protrude above the substrate surface while traces are recessed below, adding vertical separation that enables probe testing without requiring the probes to be smaller than the trace pitch.
2Quantity of substance
If the trace pitch is reduced to increase connection density, then more connections can be made, but solder bonds inadvertently bridge connections with adjacent traces
Solution Approach 1:
The conductive structures are segmented into protrusion bump pads and recessed traces, creating physical separation in the vertical dimension. This segmentation prevents solder bonds from bridging adjacent traces while maintaining high connection density, as the recessed traces are below the bonding plane.
Solution Approach 2:
Different local qualities are applied to different conductive structures: bump pads have a protruding geometry optimized for bonding, while traces have a recessed geometry optimized for isolation. This local differentiation ensures reliable bonding at pad locations while preventing accidental contact between traces.
3Ease of operation
If all conductive pillars are formed with protrusion bump pads, then probe testing is easier, but short circuits may occur during testing due to probe contact with adjacent structures
Solution Approach 1:
The invention segments the conductive pillars into two functional groups: those with protrusion bump pads for probe testing and those with recessed traces for isolation. This segmentation allows probes to easily contact bump pads while the recessed traces remain below the probing plane, preventing short circuits.
Solution Approach 2:
The recessed traces act as an intermediary structure that provides electrical connectivity while physically isolating itself from the probe testing process. The recessed geometry mediates between the need for high connection density and the need to prevent accidental probe contact.
Data Source
AI summary
A die and a substrate are provided. The die comprises at least one integrated circuit chip, and the substrate comprises first and second subsets of conductive pillars extending at least partially therethrough. Each of the first subset of conductive pillars comprises a protrusion bump pad protruding from a surface of the substrate, and the second subset of conductive pillars each partially form a trace recessed within the surface of the substrate. The die is coupled to the substrate via a plurality of conductive bumps each extending between one of the protrusion bump pads and the die.