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Strain-Based Measurement Introduction:the bending diaphragm is well-supported and no mechanical joints ordissimilar materials are present.FIGURE 1-53. The Cup Diaphragm Structure:Diffusion ZonesLeadsSilicon Substructure(N-Type typically)The silicon clamp and diaphragm must ultimately be sealed to an outerhousing, or made into a free-floating and hermetically-sealed pressurecapsule, to ensure that the internal pressure reference is maintained(Figure 1-54). The joining method commonly used to bond the sealingplate to the cup-diaphragm structure is known as the Mallory bond andis performed at elevated temperature by applying a high voltagebetween the two highly-polished surfaces. The electrostatic forces thatresult, due to the applied voltage potential between the two parts, producea high-quality nuclear-level seal between the two parts. Since thestrain gages are a diffused, and integral component of the bending diaphragmwith no adhesive bonding material required, the cup structureoffers a stable and low-hysteresis sensor design.FIGURE 1-54. The Cup-Diaphragm Mallory-Sealed Capsule:Diffusion ZonesLeadsP refMallory BondCHAPTER 1-86 The Art of Practical and Precise Strain Based Measurement 2nd Edition © 1999