Some embodiments include an apparatus comprising a spray head to spray a substrate, the substrate having a region to be sprayed and a region to be masked, the two regions separated by a boundary, and a mask having channels, the mask located between the spray head and the substrate. In an embodiment, the mask further has a lip to prevent flux overspray from falling onto a substrate below. In an embodiment, flux overspray removal is assisted with a vacuum system. Other embodiments are described and claimed.