Ever wondered how PCBs are manufactured? Zach Smith, a co-founder of MakerBot Industries, posted a fascinating article on Haxlr8r explaining what it’s all about.
After the reflow process, you will have a board that can be tested. Common mistakes during the previous process will result in components that are not connected, shorts that connect portions of the circuit that should not be connected, or misaligned components. There are a variety of ways to check for this ranging from a quick look-over by a human, automatic optical inspection using image recognition, or even x-raying to look through components that might block your view such as BGA chips.