Vertical Probe Test Fixture for Dense Wafer Contact
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Solution Overview
Problem
Probes with obliquely-inserted or bent configurations face issues such as non-contact with the wafer or scratching due to excessive length, limiting arrangement density, and the use of high-speed electroplating for metal bumps results in substrate skewing and thickness limitations.
Innovation Solution
A test fixture design comprising a probe layer, resin layers, circuit layers, and a solder mask layer with probes having a copper core and strengthened layer, configured in an inverted structure to ensure uniform height and direction, manufactured using mature circuit board processes without oblique or bent configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If probes are inserted obliquely or configured as bent structures to correspond to openings on the probe plate, then the probe can contact the wafer, but the arrangement density of the probes is limited due to assembling tolerance issues causing non-contact or scratching
Solution Approach 1:
The patent inverts the conventional probe structure by making probes vertically inserted and straight instead of oblique or bent. The probe plate openings are configured to receive vertical probes, reversing the traditional approach where probes needed to be angled to match opening positions. This inversion eliminates arrangement density limitations while maintaining reliable contact.
2Manufacturing precision
If polishing technique is applied to form bumps with identical height by using high-speed electroplating, then uniform bump height is achieved, but the substrate is squeezed and becomes skewed limiting substrate thickness
Solution Approach 1:
The patent extracts and eliminates the polishing step from the manufacturing process. Instead of using high-speed electroplating followed by polishing to achieve uniform bump heights, the invention uses a direct electroplating process with controlled parameters that produce uniformly heighted bumps without requiring subsequent mechanical polishing, thereby avoiding substrate deformation.
3Reliability
If probes are made longer to ensure contact with the wafer, then contact reliability improves, but the probes may scratch the wafer due to excessive length
Solution Approach 1:
The patent changes the geometric parameters of the probe structure, specifically making probes vertical and straight with controlled lengths. By adjusting the probe length parameter to be sufficient for contact but not excessive, and combining this with the vertical orientation, the invention achieves reliable contact while preventing wafer scratching that occurs with longer, angled, or bent probes.
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
Prevents probe misalignment and scratching, increases product yield, and reduces manufacturing costs by ensuring uniform probe alignment and avoiding substrate deformation.
Implementation Method 1
Each of the probes comprises a copper core layer and a strengthened layer, and the strengthened layer encloses an outer surface of the copper core layer
Implementation Method 2
the metal bumps are defined by photoresist firstly and then are manufactured using high-speed electroplating
Implementation Method 3
the metal bumps are defined by photoresist firstly
Data Source
AI summary
A test fixture includes a probe layer, a first resin layer, a first circuit layer, a second resin layer, a second circuit layer, a solder mask layer, and a bonding pad layer. The probe layer includes probes. The first resin layer is on the probe layer. The first circuit layer is on the first resin layer and connected to the probe layer. The second resin layer is on the first circuit layer. The second circuit layer is on the second resin layer and electrically connected to the first circuit layer. The solder mask layer is on the second circuit layer and the second resin layer and has bonding pad openings. The bonding pad layer includes bonding pads in the bonding pad openings and is electrically connected to the second circuit layer. A first pitch between the bonding pads is greater than a second pitch between the probes.