DISCRETE WIRING DEADBUGS | |
The term "Deadbugs" is an industry nickname for the discrete components added and wired into a printed wiring assembly (PWA) to facilitate active circuit modifications, rather than redesign and manufacture a new board. The nickname comes from their general appearance on the board: upside down, with their termination leads (legs) up in the air - like a dead bug. |
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PREFERRED AXIAL-LEADED COMPONENT Component is properly mounted. Lead bends are within limits. Terminations are properly wrapped. The solder joints meet all minimum requirements. Jumper wires have appropriate stress relief. Best Workmanship Practice |
PREFERRED GLASS-BODIED COMPONENT Component is covered with a transparent resilient sleeving, and properly mounted. Lead bends are within limits. Terminations are properly wrapped. The solder joints meet all minimum requirements. Jumper wires have appropriate stress relief. Best Workmanship Practice |
PREFERRED DUAL-INLINE PACKAGE (DIP) Component is properly mounted and terminated. Jumper wires are properly terminated, with appropriate stress relief. The solder joints meet all minimum requirements. Best Workmanship Practice |
PREFERRED RADIAL-LEADED COMPONENT Component is properly mounted and terminated. Lead bends are within limits. Terminations are properly wrapped. The solder joints meet all minimum requirements. Jumper wires have appropriate stress relief. Best Workmanship Practice |
NASA WORKMANSHIP STANDARDS | |||
Released: 05.31.2002 |
Revision: |
Revision
Date: |
|
Book: 3 |
Section: 3.03 |
Page: 1 |
DISCRETE WIRING DEADBUGS (cont.) | |
PREFERRED SURFACE MOUNT TECHNOLOGY Component is properly mounted and terminated. Jumper wires are properly terminated, with appropriate stress relief. The solder joints meet all minimum requirements. Best Workmanship Practice |
PREFERRED SURFACE MOUNT TECHNOLOGY Component is properly mounted and terminated. Jumper wires are properly terminated, with appropriate stress relief. The solder joints meet all minimum requirements. Best Workmanship Practice |
PREFERRED TO-CAN COMPONENT Component is properly mounted and terminated. Lead bends are within limits. Terminations are properly wrapped. The solder joints meet all minimum requirements. Jumper wires have appropriate stress relief. Best Workmanship Practice |
ACCEPTABLE AXIAL COMPONENT PIGGYBACK Axial components may be piggybacked to axial components in a vertical or horizontal orientation, but shall be staked. Terminations shall meet minimum lead seal spacing, lead bend, wrap and solder fillet requirements. Best Workmanship Practice |
ACCEPTABLE CHIP/MELF/METALLIZED TERMINALS Chip component mounting to a single pad is acceptable, provided the component is properly staked to prevent stress to the solder joints or the component body. Best Workmanship Practice |
ACCEPTABLE PIGGYBACKING/STACKING The components are in vertical alignment, with no overhang. The terminations exhibit fully wetted solder fillets and the stack does not exceed two (2) components high. Best Workmanship Practice |
NASA WORKMANSHIP STANDARDS | |||
Released: 05.31.2002 |
Revision: |
Revision
Date: |
|
Book: 3 |
Section: 3.03 |
Page: 2 |
DISCRETE WIRING DEADBUGS (cont.) | |
ACCEPTABLE PIGGYBACKING/STACKING TO ICs IC piggybacking is acceptable when space and/or noise requirements prohibit more traditional placement methods. Component leads/jumper wires shall meet minimum bend requirements. Best Workmanship Practice |
UNACCEPTABLE IMPROPER LEAD DRESS Dead-bugged components shall be mounted and dressed in a manner that prevents shorting of the leads to the component case (pictured) or to other conductors. Best Workmanship Practice |
UNACCEPTABLE IMPROPER MOUNTING ORIENTATION Components shall be mounted with the leads in an orientation that ensures the terminations meet minimum electrical spacing requirements. As pictured, the component terminals are resting on exposed circuitry and vias. Best Workmanship Practice |
UNACCEPTABLE IMPROPER MOUNTING Chip and MELF devices shall not be directly mounted on component leads of integrated circuit (chip) packages. Best Workmanship Practice |
UNACCEPTABLE IMPROPER SOLDER TERMINATION Jumper wires shall be lap soldered to the device leads. Wrapped terminations place stress on the component lead, and may violate minimum lead-to-lead electrical spacing requirements. Best Workmanship Practice |
UNACCEPTABLE IMPROPER STAKING The component shall be secured with an adhesive material, per engineering documentation. Best Workmanship Practice |
NASA WORKMANSHIP STANDARDS | |||
Released: 05.31.2002 |
Revision: |
Revision
Date: |
|
Book: 3 |
Section: 3.03 |
Page: 3 |
DISCRETE WIRING DEADBUGS (cont.) | |
UNACCEPTABLE IMPROPER TERMINATION WRAP Jumper wires shall be wrapped at least 180° to 270° around the component lead prior to soldering, and shall not be located closer than one (1) lead diameter to end of the component lead. Best Workmanship Practice |
UNACCEPTABLE PIGGY-BACK/STACKING The piggy-backing/stacking of cylindrical/glass-bodied/MELF components is not recommeneded. Best Workmanship Practice |
UNACCEPTABLE TOMBSTONED TERMINATION Deadbugged components shall be mounted parallel to and in contact with the base laminate, or base component (if applicable). Tombstoning places unacceptable stress on the component/solder pad termination. Best Workmanship Practice |
NASA WORKMANSHIP STANDARDS | |||
Released: 05.31.2002 |
Revision: |
Revision
Date: |
|
Book: 3 |
Section: 3.03 |
Page: 4 |
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