Burn-In Test Method for Laser Diodes with Variable Electrode Roughness
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Solution Overview
Problem
The existing burn-in test methods for thermally-assisted magnetic recording heads with a composite slider structure are inefficient due to the difficulty in stably supplying power to multiple laser diodes with different electrode heights, leading to unstable contact and high costs associated with needle probes, and the challenge of achieving reliable contact with sheet-type probes.
Innovation Solution
A method involving sheet-type probes with higher surface roughness for upper electrodes and lower surface roughness for lower electrodes, allowing stable contact and efficient power supply to laser diodes on a unit bar, enabling simultaneous burn-in testing of multiple laser diodes before they are diced into individual chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If needle probes are used to supply power to multiple laser diodes with different electrode heights, then power supply is achieved, but contact stability is poor and probe replacement frequency increases
Solution Approach 1:
The invention changes the surface roughness parameter of the electrodes to match the probe tip curvature radius. By controlling the RMS surface roughness to be 0.03-0.3 μm (preferably 0.05-0.2 μm), the electrode surface becomes compatible with the probe tip geometry, ensuring stable contact without requiring frequent probe replacements.
Solution Approach 2:
The invention applies different surface roughness characteristics to different electrodes based on their specific positions and functions. The first electrode (higher position) and second electrode (lower position) are differentiated by their surface roughness properties, allowing each to optimize contact with the sheet-type probe at its specific location.
2Ease of manufacture
If sheet-type probes are used to supply power to laser diodes, then manufacturing cost is reduced, but contact stability with electrodes at different heights is insufficient
Solution Approach 1:
The invention modifies the surface roughness parameter of the electrodes to enable stable contact with inexpensive sheet-type probes. By controlling the RMS surface roughness within the specific range of 0.03-0.3 μm, the electrode surfaces become mechanically compatible with the flat probe tips, achieving both cost reduction and contact stability.
Solution Approach 2:
The invention creates equipotential contact conditions by matching the surface roughness of electrodes at different heights to the probe tip characteristics. This ensures that both the first electrode (higher position) and second electrode (lower position) achieve equivalent contact quality with the sheet-type probe, eliminating height-related contact instability.
3Measurement precision
If burn-in test is performed on individual laser diode chips after dicing, then testing accuracy is maintained, but testing time and man-hours increase significantly
Solution Approach 1:
The invention merges multiple laser diode testing operations into a single simultaneous test. By maintaining electrical connection to multiple laser diodes on the unit bar before dicing, the burn-in test can be performed on all devices at once, dramatically reducing total testing time while preserving test accuracy through individualized current control and monitoring.
Solution Approach 2:
The invention performs preliminary electrical connection and testing setup on the unit bar before the dicing process. By establishing probe contacts and configuring test parameters in advance, the system enables efficient batch testing that would be time-consuming if performed individually after dicing, without compromising measurement precision.
4Ease of operation
If electrodes with different heights are used to accommodate laser diode structure, then proper electrical connection is achieved, but contact stability with probes becomes difficult
Solution Approach 1:
The invention changes the surface roughness parameter of electrodes at different heights to compensate for the height difference. By optimizing the RMS surface roughness within 0.03-0.3 μm, the contact interface between the sheet-type probe and each electrode becomes stable despite the vertical position difference, ensuring reliable electrical connection.
Solution Approach 2:
The invention creates a standardized contact interface by making both the first electrode and second electrode compatible with the same sheet-type probe geometry. Through controlled surface roughness, each electrode at different heights replicates the optimal contact conditions, allowing uniform probing across multiple devices.
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 stable and reliable burn-in testing of multiple laser diodes simultaneously, reducing man-hours and time required for evaluation, while avoiding the need for frequent replacement of expensive needle probes and improving contact stability.
Implementation Method 1
a first sheet-type probe for the first electrode and a second sheet-type probe for the second electrode are brought into contact with the first electrode and the second electrode, respectively
Implementation Method 2
an electric current is supplied through the first electrode and the second electrode with the first sheet-type probe and the second sheet-type probe
Data Source
AI summary
Provided is a method for performing a burn-in test on an object under test in which a plurality of electrodes are provided in positions at different heights. The method comprising steps of: preparing an object under test in which an electrode in a higher position have a higher surface roughness among the plurality of electrodes; bringing a plurality of sheet-type probes into contact with the plurality of electrodes, respectively; and supplying an electric current with the plurality of electrodes through the plurality of sheet-type probes. By implementing the method, the sheet-type probes can be kept in stable contact with the electrodes because electrodes in a higher position have a higher surface roughness Ra than electrodes in a lower position. Consequently, stable and reliable burn-in test can be performed.