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66 SMT007 MAGAZINE I MARCH 2018 "Dead bug" attachment of electronic compo- nents is a way of building functioning elec- tronic circuits by soldering the parts directly together or by soldering miniature jumper wires between the component leads and the PCB lands instead of the traditional surface mount or through-hole soldering of compo- nents onto a printed circuit board (PCB). The dead bug electronic component attachment was named because when you invert the IC and bend the legs out it will look like a dead bug. There are numerous reasons why this method of electronic component attachment would be done as part of the PCB rework process: • The component is nonstandard or you do not have a library design for the pad configuration of the component • A board modification or "re-spin" takes too long from beginning to end • A layout error and the package configura- tion does not match the board layout • The device may be available in the time you need it, but not in the device package configuration of your design • It is an easier and or less expensive method to test a concept before putting in the time and effort to get boards fabricated, thereby making it useful for prototyping Several weaknesses are related to a dead bug attachment of a device to a PCB. Once the dead bug modification has been made, it is very difficult to modify or rework this part of the PCB. With the electronic component many times being encapsulated to provide mechani- cal rigidity, re-working the dead bug becomes Knocking Down the Bone Pile by Bob Wettermann, BEST INC. Device "Dead Bugging" Figure 1: Dead bug attachment of QFP to different pads on a PCB due to a layout problem.

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