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Ultra-High Density Magnetic Heads

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Presentation on theme: "Ultra-High Density Magnetic Heads"— Presentation transcript:

1 Ultra-High Density Magnetic Heads
Ken Gilleo – ET-Trends – Nathan Kerrick, Cookson Electronics MEMS & GMR Technology IMAPS 200 Denver IBM MicroDrive: 351 MB © ET-Trends LLC

2 OUTLINE Hard Disk Drive overview GR and GMR technology
Processing of hi-density heads The role of temporary adhesives HDD assembly © ET-Trends LLC

3 The HDD (Hard Drive Disk)
Magnetic Disk Positioner Assembly Mag. Head Assembly Flex Slider © ET-Trends LLC Courtesy of 3M Co

4 The HDD Head is key to Ultra-High Density
© ET-Trends LLC

5 HDD Technology Density increases surpass Moore’s Law.
MR and GMR are true breakthroughs. Density records: 30 million bits/in2 December 1999 (commercial) 56 Gbits/in2 on April 2000 (lab) Density limits have not been reached. The technology is in the complex head. © ET-Trends LLC

6 MR Head Technology I bias Magneto-Resistive Measure  as “read” signal
MR Effect: changes in electrical resistance by certain magnetically-soft when a magnetic field is turned on and off. Shield Shield Soft Adjacent Layer Contact MR Sensing Layer (changes resistivity) Insulator Spacer © ET-Trends LLC

7 GMR Head Technology I bias Giant Magneto-Resistive Shield Shield
GMR is a quantum effect and relies on electron spin states; >2X more sensitive than GR Exchange Layer Contact Sensing Layer Pinned Layer (magnetically oriented) Conducting Layer © ET-Trends LLC

8 Write Head COIL Write Current SLIDER Coil WRITE HEAD Magnetic medium Magnetic coil creates field that“writes” by orienting disk domain medium ON ON Writing Current © ET-Trends LLC

9 Merged Read/Write Head
Shield 2 WRITE READ Inductive Writing Element Shield 1 MR or GMR Sensor Rotating Disk N S S N N S S N N S S N READ WRITE © ET-Trends LLC

10 Building MR/GMR Head Elements
Semiconductor wafer fab Wafer thinning Wafer sawing Element planing/polishing Head assembly Temporary Adhesives © ET-Trends LLC

11 First, some adhesive basics.
Mixing Casting Adhesive film © ET-Trends LLC Wafer-applied adhesive for die attach

12 POLYMERS - Engineered molecules -Tailored properties
Long-chained typically organic macromolecules made up of small repeating segments of monomers. Properties such as strength, flexibility, melting point and electrical characteristics can be ENGINEERED into the polymer. POLYMERS - Engineered molecules -Tailored properties - Highly compatible © ET-Trends LLC

13 Thermoplastic Thermoset SOLID LIQUID SOLID SOLID
A polymer that is capable of softening to a flowable "liquid" when heated and hardened again when cooled. SOLID LIQUID (flowable) Thermoset A polymer that is cross-linked so that melting does not occur under heating. SOLID SOLID © ET-Trends LLC

14 Polymer Types © ET-Trends LLC

15 Thermoplastic as a temporary adhesive
Independent chain motion allows melting; debonding. No cross-links © ET-Trends LLC

16 can be dissolved or debonded without dissolving; swelling
No cross-links Solvent Molecules Thermoplastics can be dissolved or debonded without dissolving; swelling © ET-Trends LLC

17 Thermoplastic Adhesive FORMS
Film sheets rolls Preform any shape from disk to complex Paste for needle dispense spin coat for wafer-level © ET-Trends LLC

18 Resin & Filler Choices Fillers Resin bond ranges (thermoplastics):
Silver - Electrical & thermal conductivity AlN, BeO - Thermal, but good dielectric Unfilled - Insulating Resin bond ranges (thermoplastics): Low : 100oC High :400oC Typical: oC Sometimes used to control static. For Most HDD Processes © ET-Trends LLC

19 -------------Thermoplastic -------------
Thermoset Adhesives Not Temporary Paste to Substrate Dispense Place Oven Cure No Pressure Needed Thermoplastic Paste to Substrate Dispense or Print Place Part Dry/Fuse No Pressure Needed Paste to Wafer Coat Wafer: spin, print Place Part Heat & Pressure DRY FILM Place Preform Place Part Heat & Pressure © ET-Trends LLC

20 Application Processes
Liquid (paste) Coat on wafer; spin, stencil, print; dry Needle dispense on substrate or holder Film Laminate to wafer, then run processes Preform (cut to wafer of row shape) Bond to wafer Bond to substrate © ET-Trends LLC

21 Bonding Thermoplastics
Process Window Viscosity Glassy State Plastic State Decomposition Temperature Tg Tmin Tmax © ET-Trends LLC

22 Thermoplastic Properties
Tg Bond Temp Rework Die Shear Thermal Modulus Which ones for HDD? FILLERS C C Cmin. 25C WmC PSI none -40 110 1700 0.2 60K Ag, AlN none -25 160 2200 60K Ag, AlN none 45 170 2600 500K Ag, AlN none 98 170 3000 400K None 145 210 150K 3800 0.22 Ag, AlN none 180 350 4000 360K None 280 400 4900 0.25 370K Each row is a different polymer © ET-Trends LLC

23 Bond Strength of Die Attach Adhes.
SUBSTRATE CONDITIONING INITIAL BOND FINAL BOND Ceramic 150oC, 1000 hrs. 2500 PSI 4800 PSI Au-plated 150oC, 1000 hrs. 3100PSI 4900 PSI Ceramic Al 150oC, 1000 hrs. 4100 PSI 4500 PSI 85%RH, 85oC, Ceramic 2500 PSI 1800 PSI 1000 Hrs. Au-plated 85%RH, 85oC, 3100 PSI 2600 PSI Ceramic 1000 Hrs. 85%RH, 85oC, Al 4100 PSI 3600 PSI 1000 Hrs. -65oC to 150oC, Ceramic 2500 PSI 4000 PSI 500 cycles Au-plated -65oC to 150oC, 3100 PSI 3700 PSI Ceramic 500 cycles -65oC to 150oC, Al 4100 PSI 4800 PSI 500 cycles © ET-Trends LLC Bonding: 180C/ 10sec, 135g; .080" x .080" Ni/Au Kovar

24 Removal Options Heat element area Peel off parts
Immerse assembly in solvent Remove parts Rinse in solvent Preferred for HDD work SOLVENT © ET-Trends LLC

25 Wafer Lapping (thinning & polishing)
Attach wafer to lava stone with temporary adhesive. HDD Wafer © ET-Trends LLC

26 Wafer Lapping Process Holder Lava Rock Wafer Grinding Media Temporary
Adhesive Rotation © ET-Trends LLC

27 Slicing Temporary adhesive 1. Heat Bond Wafer 2. Slice into Rows
3. Debond with Solvent (sawing into rows) Temporary adhesive Rows formed after slicing ROW of Heads before singulating © ET-Trends LLC

28 Lapping & Edge Polishing
1. Dispense Adhesive 2. Mount Rows 3. Bond by heating Adhesive Paste Automatic Dispenser - Speedline © ET-Trends LLC

29 Row Bonding Step Rotate 90o with cut, or rough side facing up.
(part of lapping & polishing) Rotate 90o with cut, or rough side facing up. Temporary Adhesive © ET-Trends LLC

30 Rows are planarized/leveled/lapped
Debond in solvent © ET-Trends LLC

31 Finished rows are sliced into head elements
Use temporary adhesive © ET-Trends LLC

32 HDD Assembly © ET-Trends LLC

33 Cheers for HDD Industry
Conclusions HDD Beats Moore’s Law and IC industry The breakthrough was GMR MEMS is playing a role Density limits have not been reached Photonics is being added Expect continuous density increases 73 GB IBM Cheers for HDD Industry © ET-Trends LLC

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