|
|
|
|
|
|
|
|
Alternative to Dead Bug Rework
Production Floor |
|
Authored By:Andy Price, Peter Vigneau Circuit Technology Center Haverhill, MA USA For more information visit: Alternative to Dead Bug Rework TranscriptIf you're not familiar with dead bugging it's when you need to add components to a circuit board and have no place to put them so you glue them upside-down and run jumper wires to complete the circuits. It's usually a big mess. A military contractor had to implement an engineering change that involved the addition of 16 components. The original solution was to dead-bug the components and add 30 jumper wires to complete the circuits. As usual the need was urgent and there was no time to re-spin the artwork and fabricate new boards. The new solution was to bond copper conductor foil patterns directly to the circuit board surface. Components could then be soldered to the new copper foil patterns at locations designed for each component. This method eliminated 27 of the 30 jumper wires that would have been needed if the dead-bug method was used. Accuracy and placement of the new conductor patterns was critical because these were bare circuit boards and the contract manufacturer wanted to run them through the normal stencil printing, placement and reflow process. So how was it done? First artwork was prepared to encompass the patterns needed, then the patterns were promptly manufactured. These copper foil patterns have a dry-film adhesive backing and are designed precisely for this type of application. To provide a flat surface and to ensure accuracy, solder mask was milled away from the area where the new circuit patterns would be bonded. This was done using a milling machine. Next the new copper foil patterns were trimmed, precisely positioned using a reference point, and then thermally bonded in place using a heated bonding system. This dry-film adhesive bonding method is a common IPC recommended method for replacing conductors such as surface mount and BGA pads. With the new circuit patterns in place the assembly contractor was able to run the bare circuit boards through the normal assembly process and complete the rework by adding just 3 jumper wires. This was a truly elegant alternative to the messy option of dead bugging. For more information visit: http://www.circuitrework.com/features/682.shtml |
|
Comments
|
|
|
|
|
|
|
|
|