Flexure Assembly Dielectric Spacer for Signal Bandwidth
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Solution Overview
Problem
Current tail tack assembly methods in hard disk drives fail to control the vertical location of the suspension circuit tail within the actuator arm gap, leading to significant variations in electrical impedance and bandwidth, particularly at high data rates exceeding 4 GHz.
Innovation Solution
Incorporating a thin dielectric shim or a thickened covercoat spacer to maintain a minimum separation between the circuit traces and the conductive actuator arm wall, ensuring consistent signal bandwidth by minimizing electrical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the suspension circuit tail is tacked in the actuator arm slot using conventional methods, then the assembly process is simple and fast, but the vertical location of the circuit tail cannot be controlled, leading to significant variations in electrical impedance and bandwidth
Solution Approach 1:
A dielectric spacer is introduced as an intermediary component between the circuit tail and the actuator arm slot. This spacer serves as a mediator that precisely controls the vertical position of the circuit tail while maintaining electrical isolation, thereby achieving controlled impedance without significantly complicating the assembly process
Solution Approach 2:
The dielectric spacer is pre-positioned or pre-attached to the circuit tail before insertion into the actuator arm slot. This preliminary action ensures that the vertical location is predetermined and controlled, eliminating the need for complex post-assembly adjustments while maintaining manufacturing simplicity
2Object-affected harmful factors
If the circuit tail is inserted deeper into the actuator arm slot, then electrical coupling with the arm is reduced, but the signal bandwidth becomes highly sensitive to insertion depth variations
Solution Approach 1:
The dielectric spacer acts as a stable intermediary that establishes a fixed separation distance between the circuit tail and the actuator arm. This consistent spacing reduces electrical coupling while eliminating sensitivity to insertion depth variations, as the spacer maintains a predetermined gap regardless of how deeply the tail is inserted
Solution Approach 2:
The invention changes the critical parameter from insertion depth (which varies with assembly tolerances) to spacer thickness (which can be precisely controlled during manufacturing). By controlling the spacer thickness rather than the insertion depth, the design achieves both reduced electrical coupling and consistent bandwidth
3Speed
If high data rates exceeding 4 GHz are used, then storage capacity and speed are improved, but electrical impedance variations significantly degrade signal bandwidth
Solution Approach 1:
The invention addresses high-frequency signal integrity by changing the impedance control parameter from variable insertion depth to fixed spacer thickness. This ensures consistent electrical characteristics at high data rates exceeding 4 GHz, preventing bandwidth degradation while maintaining improved storage capacity and speed
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
The solution ensures a stable and high signal bandwidth by maintaining a consistent separation distance between the circuit traces and the actuator arm, preventing impedance variations and ensuring bandwidth remains above 1 GHz even at high data rates.
Implementation Method 1
Incorporating a thin dielectric shim or a thickened covercoat spacer to maintain a minimum separation between the circuit traces and the conductive actuator arm wall, ensuring consistent signal bandwidth by minimizing electrical coupling
Data Source
AI summary
In a disk drive having a flexible circuit tail that is routed within a recess in the actuator arm, a dielectric spacer is added to the top of the tail in order to space the circuit traces within the tail further away from the electrically conductive actuator arm, and to make more repeatable that spacing. The added spacing reduces electrical coupling and thus increases the bandwidth of the circuit. The spacer can be in the form of a section of the same viscoelastic material that is used elsewhere as a vibration dampener on the suspension, the viscoelastic material being adhered to the tail before the tail is inserted within the recess. Alternatively, the spacer can be a thickened region of the flexible circuit covercoat in the area where the tail will reside within the recess.