1. Suspension Design Progression for Increasing Shock Performance Jacob Bjorstrom Sr. Product Design Eng. Hutchinson Technology September 22, 2004
DISKCON 2004

2. Agenda Shock Terminology A Brief History of Mobile Shock Performance
Suspension/HGA Shock Design
Loadbeam, flexure, slider
Load/Unload Shock Design
Drive Design Impacts
Conclusions
Hutchinson Technology Inc., September 22, 2004

3. Terminology Shock - a sudden disturbance induced on the hard drive
G - measure of gravitational acceleration, the number of G’s is the magnitude of the shock event
Pulse width - length of time that a G load is applied
Op-Shock - a shock event applied while the drive is spinning with the slider on the disk
Non-op Shock - a shock event where the slider is parked in it’s resting position, typically in a mobile drive this would be off the disk on the load/unload ramp.
Gram - downward force supplied by the suspension to hold the slider on the disk
G/gram - suspension parameter used to determine liftoff point of the slider from the disk, for a given gram load
Hutchinson Technology Inc., September 22, 2004

4. 17X Improvement in Suspension G/Gram
Mobile Timeline
1995
1997
1999
2001
2003
2005
17X Improvement in Suspension G/Gram
3.0” FF
41 G/gram
2.5” FF
61 G/gram
2.5” FF
83 G/gram
1.0” FF
160 G/gram
0.85” FF
394 G/gram
0.85” FF
707 G/gram
Hutchinson Technology Inc., September 22, 2004

5. History of Requirements
Hutchinson Technology Inc., September 22, 2004

6. Four Major Drive Components Affect Shock Performance
2. Magnetic Disks
Recording Head
Disk Drive
3. Actuator
4. Suspension
Assembly
1. Drive Case
Hutchinson Technology Inc., September 22, 2004

7. Achieving Higher Shock
At the suspension level, the key is to reduce the effective load beam mass
Mass of the HGA past the bend radius
The further the mass is from the bend radius, the more detrimental it is to shock
Redo with Mobile suspension
LOADBEAM
SLIDER
FLEXURE
ARM / MOUNT PLATE
BEND RADIUS
EFFECTIVE MASS
Hutchinson Technology Inc., September 22, 2004

8. Beam Design and Material Thickness
Thin railed beams have less massive cross-sections, which are ideal for shock
Thick beam (101 mm) cross-section
Thin railed beam (20 mm) cross-section
Hutchinson Technology Inc., September 22, 2004

9. Mass Reduction Best for shock with acceptable resonance
Allow for strategic mass reduction
+14% Shock
+5% B1
-5% T1
-9% Sway
Hutchinson Technology Inc., September 22, 2004

10. Advanced Concept: Laminate Beams
Offers resonance improvement over thin beam designs while keeping high shock performance
Hutchinson Technology Inc., September 22, 2004

11. Effective Beam Length
9.3 mm
4.35 mm
Effective beam length is the distance from the arm / swage plate edge to the load point
A shorter distance reduces suspension mass, and increases shock and resonance performance
Tradeoffs are space constraints and increased risk of gram load loss
Hutchinson Technology Inc., September 22, 2004

12. Flexure Progression: Hub Clearance and Mass
Past
Present
Future
Hutchinson Technology Inc., September 22, 2004

13. Slider Size vs. G/Gram
The smaller the slider, the higher the G/gram for a given suspension
The G/gram delta between sliders increases as the slider becomes a larger portion of the effective mass
Pico
Femto
Hutchinson Technology Inc., September 22, 2004

14. Slider Size vs. Total G’s
The smallest head is not necessarily the best for total HGA shock performance when accounting for gram load and slider negative air bearing pressure
Pico
Femto
Hutchinson Technology Inc., September 22, 2004

15. Shrinking Form Factor
As the drive size decreases, the suspension becomes a large factor on drive level shock performance
Small form factor drives benefit from both increased suspension level G/gram and improved drive dynamics
Hutchinson Technology Inc., September 22, 2004

16. Non-op Shock
Shock failure is caused by a large deflection of the head and gimbal during shock. Parameters that affect shock performance are:
Suspension
Gimbal & Slider
Arm
Disk
Ramp
Headlift
Ramp design
Limiter design
Gimbal design
Hutchinson Technology Inc., September 22, 2004

17. Motion Control: Limiters
Suspension
Slider
Ramp
Suspension
Slider
Ramp
No limiters engaged
(large deflection of slider and gimbal)
Ramp and T-bar limiters engaged
(slider and flexure motion restrained)
Hutchinson Technology Inc., September 22, 2004

18. Headlifts Parking the slider off the disk prevents shock damage
Mass reduction at the tip of the suspension provides the best results for increased G/gram liftoff
New headlift concepts offer twice the stiffness and half the mass
Actual SEM
Standard Offset Form Headlift
New Continuous Rail Form Headlift
Hutchinson Technology Inc., September 22, 2004

19. Results Shocked at: 1000 G’s 1 ms pulse
Mainstream micro-HDD suspension
HTI leading edge micro-HDD suspension
Shocked at:
1000 G’s
1 ms pulse
No separation between disk and slider
Large displacement and probable disk/head damage
Hutchinson Technology Inc., September 22, 2004

20. Systems View
While the suspension is a large factor in drive shock performance, all components in the system must work together for optimal performance
The same suspension can have different shock performance in different drive designs
Hutchinson Technology Inc., September 22, 2004

21. Conclusions
Shock has become a primary differentiator in mobile drive performance.
New HTI suspension designs continue to expand the current drive level shock performance envelope.
To maximize drive level shock performance, all components must be designed in harmony with one another.
Hutchinson Technology Inc., September 22, 2004