Pseudo Flexure for Disk Drive Circuit Testing
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Solution Overview
Problem
Current methods for testing electronic circuits in disk drives, particularly those with magnetic heads, face challenges in accurately evaluating electrical properties due to the miniaturization of magnetic heads and the difficulty in stabilizing probing on narrow pads, leading to variations in electrical properties and deformation of the gimbal portion.
Innovation Solution
A pseudo flexure with a test coupon is developed, featuring a conductive circuit portion, a substrate, a dielectric layer, and metal layers with specific conductor structures to simulate the electrical properties of a magnetic head, allowing for stable testing without mounting the actual magnetic head, using a substrate with stainless steel and copper layers, and a dielectric layer to replicate the circuit's behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the magnetic head is miniaturized to reduce width, then the pad pitch becomes smaller, but it becomes difficult to accurately contact the probe on the pads
Solution Approach 1:
The patent creates a pseudo magnetic head that copies the essential electrical characteristics (inductance, resistance, capacitance) of the actual magnetic head without replicating its physical structure. This allows testing to be performed on a larger, more manageable device that maintains electrical equivalence, thereby solving the probing accuracy problem while preserving the need for miniaturization in the actual magnetic head
Solution Approach 2:
The pseudo magnetic head acts as an intermediary between the test apparatus and the actual magnetic head. It provides stable probing surfaces and equivalent electrical properties, serving as a mediator that enables accurate measurement without requiring direct probing of the miniaturized magnetic head pads
2Reliability
If the magnetic head is mounted on the flexure for testing, then electrical properties can be evaluated, but the magnetic head is easily swung and stable probing becomes difficult
Solution Approach 1:
Instead of testing the actual mounted magnetic head, the patent creates a pseudo magnetic head that copies its electrical behavior. This pseudo device can be tested in isolation without mounting concerns, eliminating the stability problem while maintaining electrical property evaluation capability
Solution Approach 2:
The testing process is segmented into two independent parts: the pseudo magnetic head for electrical characterization and the actual magnetic head for final installation. This allows the electrical properties to be evaluated separately on a stable platform, decoupling the testing stability requirement from the mounted configuration
3Measurement precision
If the probe is pressed strongly against the pad to ensure contact, then probing accuracy improves, but the gimbal portion may be deformed and electrical properties may vary
Solution Approach 1:
The pseudo magnetic head provides probing surfaces that replicate the electrical characteristics without the fragile gimbal structure. This allows strong probe contact to be made on the pseudo device's robust surfaces without risking deformation of delicate components
Solution Approach 2:
The pseudo magnetic head serves as an intermediary that absorbs the mechanical stress of strong probing. The probe force is applied to the pseudo device's durable structure rather than the actual magnetic head's delicate gimbal portion, protecting it from deformation
Data Source
AI summary
A test coupon includes a pseudo element circuit which is constituted of a main circuit section and an adjusting section. The main circuit section includes a first pattern conductor and second pattern conductors. The first pattern conductor and the second pattern conductors overlap one another with a dielectric layer interposed therebetween. The first pattern conductor electrically conducts to the second pattern conductors. The main circuit section represents the R-component and the L-component of an equivalent circuit, and is a dominant circuit element which determines a signal waveform. The adjusting section includes linear conductors. A peak of a voltage waveform is suppressed by the R- and L-components of the adjusting section.