QuickPack - Technical Notes

Tech notes - 5

Integrating the Quickpack qp16fs into a flat panel moniter

The Mide QuickPack QP16FS transducer is a member of the QuickPack actuator family of products. It is a packaged, piezoceramic device that may bonded to a surface and operated as an alert device or a full range speaker. With a thinness of only 0.013", its an ideal solution for thin products and tight spaces. And since the device does not require any grilles or speaker holes, it provides an extremely robust solution for products that will be used in harsh environments.

Operating the QP16FS transducer requires bonding the device to the OEM product housing. Supplying the transducer with an audio signal drives the transducer which induces curvature in housing --providing speaker capability from an extremely thin device.

There are a variety of methods for integrating the QP16FS transducer into an OEM product. This note outlines a reliable integration method for the QuickPack transducer. It is the method used to fabricate the Mide Invisible Speaker demonstration unit. Mide can work with OEM manufacturers to design and implement alternative methods.

1. Select Location

Since the QuickPack transducer resonates the OEM product housing itself, it should be placed in a location that provides a suitable case panel radiating surface. For optimum performance the QP16FS transducer should be bonded to a flat panel with twice the actuator's area (~ 1.41" x 2.82"). This area should be free of stiffening ribs. A typical panel made of ABS/Polycarbonate or similar plastic should be between 0.050" and 0.070" thick. (contact ACX for recommendations on alternate materials.) If the actuator is bonded to a larger structure which is nominally thicker, the surface should be thinned locally to the recommended thickness in a ~1.41" x 2.82"area. This thickness provides a suitable radiating surface while preventing most visible shadows on the outer plastic surface. A thicker, more stiff panel will reduce the sound output of the speaker.

2. Prepare Surface

Prior to bonding, the surface of the plastic and the surface of the actuator should be cleaned with a mild solvent such as isopropanol (acetone is not recommended) to remove any oils or release agents left during handling of the parts. Although excess epoxy on the panel or around the edges of the QuickPack actuator will not affect performance, masking may be desired for aesthetic purposes. Teflon tape can be used to mask around the bond location, preventing excess epoxy from adhering to the surrounding panel. When the Teflon tape is removed from around the actuator, the exposed panel and actuator surfaces are left clean.

3. Bond

Mide recommends Loctite 498 or similar quickcuring cyanolacrylate adhesive. This adhesive provides suitable strain transfer and meets typical OEM environmental requirements including temperature and high thermal cycling. Spread the adhesive uniformly on the QP16FS surface. Be careful not to cover the exposed solder pads with adhesive. Quickly place the actuator on the panel in center or slightly off center of the 1.41" x 2.82" area. (Center actuation increases sensitivity of the transducer, but off center actuation improves flatness by reducing excitation of standing wave modes.) Hold the actuator in place with a teflon coated flat block of sufficient size to cover the actuator, but small enough not to touch any nearby structural features which are thicker than the QP16FS. The thickness of the bond layer should be minimized for optimum performance. Hold the block in place with a weight of 20-30 lbs for 3-5 minutes. Remove the weight and block (use slight twisting motion if the teflon coated block sticks to the excess adhesive).

4. Electrically Connect

Solder electrical leads to the exposed solder pads and drive transducer with a 50V power amplifier or with a 10V audio amp and ACX audio transformer.

5. Prevent buzzing

Since the product housing is vibrating, the OEM must take care to ensure that nearby components, such as cables or other parts of the housing do not rattle or buzz. ACX recommends that components be spaced at least 0.06" from the vibrating housing part or be rigidly mounted to the vibrating structure. Cables and wires may be easily rigidly mounted using an adhesive or tape.

Any components closer than the minimum distance but not rigidly attached to the vibrating structure must be protected from impact with the structure by closed cell foam (0.03" minimum thickness recommended) or other soft elastic material such as neoprene. A foam gasket would be appropriate, for example, to prevent a monitor bezel from buzzing against the LCD.

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For more information:

Please email Conor Clery (Products), or call: 781-306-0609 x292