DPBU Application Note
Vacuum Release™ Trays
Vacuum Release™(VR Series) Trays hold devices securely in place during shipping or handling, similar to the AD, BD and CD Series products, but offer the unique ability to release the devices on demand.
The patented Vacuum Release process relies on changing the surface contact area between the device and the GEL membrane on the tray surface. In the "Retention" mode (figure 1 below), the surface contact is maximized and the devices are held firmly in place. In the "Release" mode (figure 2 below), the surface contact is minimized by applying vacuum to draw the GEL membrane away from the device. Devices can then be easily removed in the vertical direction using a vacuum tool or tweezers. Follow the guidelines below for best results.
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Figure 1
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Figure 2
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Guidelines for using Vacuum Release Trays:
Holding Fixture: The VR Tray should be positioned on a Vacuum Plate designed to deliver vacuum to the underside of the tray. Most die-attach equipment manufacturers offer fixtures for GEL-PAK handling. Stand-alone stations (VRS-24 and VHP-24) are also available.
Vacuum: Best off-load results are obtained by applying 25" Hg of vacuum. The GEL membrane may appear to be in the release mode even under relatively low vacuum conditions, but full vacuum is necessary for optimal release.
Pick-up Tools: The largest pick-up tool compatible with the device size should be used in order to deliver maximum vacuum force to the top surface of the device. For very small devices, increasing the bore size of the pick-up tool may be necessary. A poor seal between the tool and device can be caused by damaged tooling or irregular edges; a soft tip on the tool will assist in device pick up.
Die contact/Removal: Contact force between the pick-up tool and the device should be minimized so that the device is not pressed into the GEL membrane. Once the device is properly engaged by the pick-up tool, the rate of ascent should initially be slow. Rapid ascent may tend to separate the device from the tool.
Membrane Tear: GEL membranes are relatively fragile and should he handled with care. If a membrane tears, then vacuum leakage at the tray will occur which inhibits device removal.
(US Patent # 4,667,944 4,711,014 4,778,326)
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