A probe card assembly includes a probe card, a space transformer having resilient contact structures (probe elements) mounted directly to (i.e., without the need for additional connecting wires or the like) and extending from terminals on a surface thereof, and an interposer disposed between the space transformer and the probe card. The space transformer and interposer are “stacked up” so that the orientation of the space transformer, hence the orientation of the tips of the probe elements, can be adjusted without changing the orientation of the probe card. Suitable mechanisms for adjusting the orientation of the space transformer, and for determining what adjustments to make, are disclosed. The interposer has resilient contact structures extending from both the top and bottom surfaces thereof, and ensures that electrical connections are maintained between the space transformer and the probe card throughout the space transformer's range of adjustment, by virtue of the interposer's inherent compliance. Multiple die sites on a semiconductor wafer are readily probed using the disclosed techniques, and the probe elements can be arranged to optimize probing of an entire wafer. Composite interconnection elements having a relatively soft core overcoated by a relatively hard shell, as the resilient contact structures are described.

Probe card assembly and kit, and methods of making same

Microelectromechanical systems (MEMS) devices are made of doped single-crystal silicon, LPCVD polysilicon films, and other ceramic films. Very little is understood about tribology and mechanical characterization of these materials on micro- to nanoscales. Micromechanical and tribological characterization of p-type (lightly boron-doped) single-crystal silicon (referred to as “undoped”), p+-type (boron doped) single-crystal silicon, polysilicon bulk, and n+-type (phosphorous doped) LPCVD polysilicon films have been carried out. Hardness, elastic modulus, and scratch resistance of these materials were measured by nanoindentation and microscratching using a nanoindenter. Friction and wear properties were measured using an accelerated ball-on-flat tribometer. It is found that the undoped silicon and polysilicon bulk as well as n+-type polysilicon film exhibit higher hardness and elastic modulus than the p+-type silicon. The polysilicon bulk and n+-type polysilicon film exhibit the lowest friction and highest resistance to scratch and wear followed by the undoped silicon and with the poorest behavior of the p+-type silicon. During scratching, the p+-type silicon deforms like a ductile metal.

Micromechanical and tribological characterization of doped single-crystal silicon and polysilicon films for microelectromechanical systems devices

A microactuator comprised of a piezoelectric motor mounted on a flexure tongue with offsetting hinges, to perform a fine positioning of the magnetic read/write head. The substantial gain in the frequency response greatly improves the performance and accuracy of the track-follow control for fine positioning. The simplicity of the enhanced microactuator design results in a manufacturing efficiency that enables a high-volume, low-cost production.

Microactuator with offsetting hinges and method for high-resolution positioning of magnetic read/write head

This paper presents the design and the characteristics of a nonvolatile memory cell using giant magneto-resistance effects. Unlike other magnetic memory cells, the present cell design exploits the full /spl Delta/R of the spin valve material. A dc voltage difference between the two cell states of 30 mV range has been realized on a cell stripe only 6-microns long, making it compatible with the high-speed sensing schemes presently employed in silicon RAMs. The cell switches states in sub-nanoseconds. Its performance/density is close to that of the static RAM cell.

Spin-valve RAM cell

Research and development in microelectromechanical systems (MEMS) have made remarkable progress since 1988, when an electrostatic micromotor the size of a human hair was first operated successfully. Since then, many types of microactuators utilizing various driving forces and mechanisms have been developed. Distinctive features of MEMS (miniaturization, multiplicity of components, and the integration of microelectronics) have led to promising application areas such as fluidic microsystems. In the future, MEMS promises to make contributions to the society of the twenty-first century in three broad areas: (1) offering easier access to information, (2) making human lifestyles more compatible with the environment, and (3) improving people's social welfare. This paper will discuss some of the technological issues pertaining to microactuators, micromachines, and the future development of MEMS.

Microactuators and micromachines

The storage capacities and areal densities found in magnetic disk drives are increasing very rapidly. Data is recorded in ever-narrower tracks which must be followed with extreme precision. Also, the advent of portable applications exposes these smaller drives to higher levels of vibration and shock. A description is given of the many factors which contribute to recording track misregistration (TMR) in today's drives. The mechanics of the drive and actuator and the architecture of the servo control system are also described. A projection is made for the TMR sensitivities and control system at an areal density of 10 Gb/in/sup 2/, having roughly 25000 tracks/in. A two-stage servo may be needed to achieve such track densities. This would comprise a high bandwidth microactuator for rapid position corrections of the recording head, coupled with a conventional actuator. The characteristics of such a microactuator are discussed, and operational examples of fabricated electroplated microactuators, driven electrostatically, are shown. The mechanical behavior of the devices and some of the factors which would affect their implementation are also described. >

Magnetic recording-head positioning at very high track densities using a microactuator-based, two-stage servo system

A method and apparatus for controlling a multiple-stage actuator for a disk drive which does not require an additional sensor for measuring the relative position between adjacent actuator stages. In a two-stage actuator system, a position-type secondary actuator (SA) rides piggyback on a primary actuator (PA). The repeatable runout is measured and used as a feedforward signal to the PA. If the PA is a rotary actuator, the feedforward signal is preferably arc corrected for the arc that the head transverses from the inner radius to the outer radius of the disk. Added to the feedforward signal is the moving average of the drive signal applied to the SA. Because the SA is of the position-type having a neutral position, this moving average is proportional to the time cumulative drift present in the two-stage actuator system, and forces the PA in a direction that minimizes deviation of the SA from its neutral position. This minimizes the range requirement for the SA, the main purpose of which is to reduce non-repeatable runout.

Method and apparatus for controlling a multiple-stage actuator for a disk drive

Disclosed is an integrated lead suspension flexure attachment structure for a micro-actuator with a slider/transducer assembly attached thereto, having a plurality of electrical terminals for both the micro-actuator and the transducer. The suspension provides low gimbal stiffness and allows the slider to have correct pitch and roll static attitudes. An attachment platform is provided for mechanically attaching the micro-actuator. Two elongate cantilever compliance members extend from the transducer edge and the opposite edge of the attachment platform. Two lead termination platforms are provided, each at the distal end of one of the compliance members. The lead termination platforms extend laterally to either side of the compliance members. Electrical leads are positioned laterally of each of the lead termination platforms on either side, and loop towards the compliance member to the lead termination platform to reduce stiffness of the leads. The two lead termination platforms each supports the electrical leads at either side of the compliance member and the compliance members allow flex between the attachment platform and the lead terminations for connecting the leads to the micro-actuator.

Integrated lead suspension flexure for attaching a micro-actuator with a transducer slider

A rotary microactuator includes a stationary structure formed on a substrate, a movable structure, and at least a pair of wires connected to the movable structure that conduct a signal associated with the movable structure. Each wire of the pair of wires has a first end that is connected in a cantilever manner to the substrate and a second end that is connected to the movable structure. The wires each have a serpentine shape between the first end and the second end, a predetermined spring stiffness, and a predetermined electrical characteristic. The microactuator also includes a magnetic head slider that is attached to the movable structure, and at least another pair of wires conducting a signal associated with a magnetic head of the slider. Each of the another pair of wires has a first end that is connected in a cantilever manner to the substrate and a second end that is connected to the movable structure. Like the first pair of wires, each of the another pair of wires has a serpentine shape between the first end and the second end of the wire. Electronic circuitry for conditioning the electrical signals associated with the magnetic head can be fabricated as part of the substrate and be connected to one of the pair of wires. The electronic circuitry can, for example, amplify electrical drive signals associated with the magnetic head, be a recording sensor preamplifier, and/or provide ESD protection for the electrical signals associated with the magnetic head.

Method and structures used for connecting recording head signal wires in a microactuator

A microfabricated wobble motor with a positioning arm attached to the wobble motor rotor acts as a fine positioner with bidirectional movement. The primary application is a rotary actuator for the read/write head in a very small magnetic recording disk drive. An integrated head-arm assembly is attached at one end to the rotor of the wobble motor. The other end of the head-arm assembly has a head carrier that is maintained in contact with the disk. Head position error information is read from the disk and used to provide control signals to each of the stator elements. The stator elements are sequentially addressed by applying a voltage from a driver circuit. This causes the rotor to be electrostatically attracted to the activated stators, so that the rotor is movable bidirectionally. The read/write head can thus be moved bidirectionally to any of the data tracks on the disk and maintained on a desired data track for reading or writing data. The fine positioner also includes a digital control system where each of the stator elements is represented by an address, and the movement of the rotor is controlled by incrementing or decrementing the stator address in an address register.

Long-Sheng Fan

Papers

Magnetic recording-head positioning at very high track densities using a microactuator-based, two-stage servo system

Method and apparatus for controlling a multiple-stage actuator for a disk drive

Integrated lead suspension flexure for attaching a micro-actuator with a transducer slider

Method and structures used for connecting recording head signal wires in a microactuator

Wobble motor microactuator for fine positioning and disk drive incorporating the microactuator