PREFERRED

ADHESIVE BONDING/STAKING

Adhesive bonding/staking material has been applied to the parts and locations specified by the approved engineering specification. Material quantity is sufficicnet to provide required support, but does not negate stress relief or mechanically compromise hardware reliability.

PREFERRED

FLEXIBLE MATERIALS

Flexible staking materials with a high thermal expansion coefficient shall not be applied where excessive stress may be damaging. As depicted, the staking material has been applied to the corners of the package.

NASA-STD-8739.1 [9.2.1]

PREFERRED

PERIPHERY RULE

Staking material shall be of sufficient quantity to result in a minimum of 20% of the component's periphery being bonded.

Best Workmanship Practice

PREFERRED

SOLDERABLE AREAS/TEST POINTS

Adhesive/staking material shall not be applied to areas that are to be soldered, or are to be used as test points. Contamination/solderability issue.

Best Workmanship Practice

ACCEPTABLE

BUBBLES

Minor bubbles in the staking material fillet are acceptable, provided they do not reduce the fillet's cross-section below minimum requirements.

Best Workmanship Practice

UNACCEPTABLE

BUBBLES

Bubbles shall not reduce the cross-section of the fillet below minimum requirements.

Best Workmanship Practice

ACCEPTABLE

BRIDGING ARRAYS

Staking material may be applied across the top of the array of parts, provided the staking covers the entire width of the top of the parts, exhibits a fillet a minimum of 2/3 of part width on each end of the array, and stress relief is not negated.

NASA-STD-8739.1 [9.2.1]

ACCEPTABLE

EXCESSIVE FILLET

Staking material exceeds 50% of the component diameter, but does not extend over the component, obliterate markings, or negate component lead stress relief.

NASA-STD-8739.1 [9.2.1], [9.2.3.a]

ACCEPTABLE

FASTENER SPOT STAKING

Staking materials shall be applied to fasteners per engineering documentation.

NASA-STD-8739.1 [9.2.1]

ACCEPTABLE

HORIZONTAL MOUNT AXIAL

Staking adheres to component a minimum of 50% of its length (L) and 25% of its diameter (D), on one side, and is centered. Proper wetting and adhesion to the part and substrate is evident.

NASA-STD-8739.1 [9.2.1]

ACCEPTABLE

JUMPER WIRES

Jumper wires shall be staked every 2.54 cm (1 in.), at a minimum, and at every change of direction outside of the radius of curvature.

NASA-STD-8739.1 [9.2.4], [11.6.2.c]

UNACCEPTABLE

BONDS IN WIRE CURVATURE

Staking along a jumper wire's radius of curvature can negate strain relief, resulting in reliability concerns.

NASA-STD-8739.1 [9.2.4]

ACCEPTABLE

MULTIPLE VERTICAL AXIALS

Staking adheres to each component for at least 50% of each component's length (L), is continuous between components, and adheres to each component a minimum of 25% of its circumference.

Best Workmanship Practice

ACCEPTABLE

SPOT TIES ON WIRE BUNDLES

Spot ties on wire bundles shall be staked per engineering documentation.

NASA-STD-8739.1 [9.2.1]

ACCEPTABLE

SUBSTRATE CONTACT

The staking material shall wet and adhere to a minimum of 50% of component length (L), and 25% of circumference, depending on mounting configuration.

Best Workmanship Practice

UNACCEPTABLE

INSUFFICIENT SUBSTRATE CONTACT

The staking material shall wet and adhere to a minimum of 50% of component length (L), 25% of circumference, depending on mounting configuration.

Best Workmanship Practice

ACCEPTABLE

TOROID STAKING-CONTINUOUS FILLET

Staking of toroids and other large footprint components shall be sufficient to provide uniform support and prevent movement.

NASA-STD-8739.1 [9.2.1]

ACCEPTABLE

TOROID STAKING-DISCONTINUOUS FILLET

The staking fillet amy be discontinuous if the application of material will interfere with adjustable components, test points, or serviceable mechanical components. The staking shall be sufficient to provide uniform support.

NASA-STD-8739.1 [9.2.1]

ACCEPTABLE

VERTICAL MOUNT AXIAL

Staking wets and adheres to the component and the substrate for at least 50% of part length (L) and 25% of part circumference. Proper wetting and adhesion to the part and substrate is evident.

NASA-STD-8739.1 [9.2.1]

ACCEPTABLE

VIBRATION ISOLATION

Staking materials applied for vibration isolation/support shall be applied per engineering documentation.

NASA-STD-8739.1 [9.2.1]

UNACCEPTABLE

BONDS IN STRESS RELIEF

Staking material shall ot negate stress relief of parts, enclose joints or part leads, or mechanically compromise the reliability of the hardware.

NASA-STD-8739.1 [9.2.3]

UNACCEPTABLE

BURIED COMPONENT LEAD

Staking material shall not encapsulate a component's lead.

NASA-STD-8739.1 [9.2.3.a]

UNACCEPTABLE

CONTACT WITH GLASS-BODIED PART

Rigid staking material is in contact with the unsleeved area of a glass-bodied component.

NASA-STD-8739.1 [9.2.3.c], [11.6.3.e]

UNACCEPTABLE

IMPROPER WETTING

Bonds do not show evidence of proper wetting and adhesion to the bottom and side of the component and the mounting surface.

NASA-STD-8739.1 [9.2.1]

UNACCEPTABLE

INSUFFICIENT BONDS

Bonds are less than specified in engineering documents and/or are less than a minimum of 4 equally spaced bonds for parts in excess of 7 gm (0.25 oz.) per lead.

Best Workmanship Practice

UNACCEPTABLE

INSUFFICIENT FILLET
HORIZONTAL MOUNT

Staking fillet height is less than 25% of the component diameter (D).

Best Workmanship Practice

UNACCEPTABLE

INSUFFICIENT FILLET
VERTICAL MOUNT

Staking extends upwards less than 50% of the component length (L).

Best Workmanship Practice

UNACCEPTABLE

INSUFFICIENT MECHANICAL SUPPORT

The staking material forms too thin a column to provide good mechanical support.

Best Workmanship Practice

UNACCEPTABLE

INSUFFICIENT PEERIPHERAL SUPPORT

Less than 20% of the total periphery of the component is bonded.

Best Workmanship Practice