Complaint membrane for restraining a workpiece and applying uniform pressure during lapping to improve flatness control

A fixture for restraining a workpiece relative to a lapping surface, comprising:

• a base having a mounting surface, an internal cavity with an opening in the mounting surface, and a port extending from the internal cavity to an exterior of the base;
• a flexible membrane having an outer surface, and an inner surface secured to the mounting surface of the base with an adhesive and extending across the internal cavity to seal the opening;
• an adhesive coating on the outer surface of the membrane;
• a fluid located in and substantially filling the cavity in the base to provide the membrane with a resilient outer surface;
• a pump for externally pressurizing the fluid through the port in the base;
• and wherein
• the membrane is adapted to support a workpiece during a lapping process that is located within an area defined by the opening such that the fluid substantially restrains the workpiece from movement in a direction normal to the membrane, and the adhesive coating substantially restrains the workpiece from movement in a direction tangential to the membrane strictly via adhesive bonding with a tangential force in a tension axis of the membrane.

A fixture for restraining a workpiece relative to a lapping surface, comprising:

• a base having a mounting surface, an internal cavity with an opening in the mounting surface, and a port extending from the internal cavity to an exterior of the base;
• a flexible membrane having an outer surface, and an inner surface bonded to the mounting surface of the base and extending across the internal cavity to seal the opening;
• an adhesive coating on the outer surface of the membrane;
• a fluid located in the cavity of the base and adapted to be pressurized through the port to provide the membrane with a resilient outer surface;
• a plurality of wear pads spaced apart from each other and the workpiece, and secured to the mounting surface of the base and adapted to provide a fixed spacing between the lapping surface and the base during the lapping process;
• and wherein the membrane is adapted to support a workpiece during a lapping process that is located within an area defined by the opening such that the fluid substantially restrains the workpiece from movement in a direction normal to the membrane, and the adhesive coating substantially restrains the workpiece from movement in a direction tangential to the membrane strictly via adhesive bonding with a tangential force in a tension axis of the membrane.