(if you want to know how much time is needed to hand assemble a board, see our other blog)
Are you impatient waiting for the assembly house building your prototype? Maybe you should try to build them quicker by hand. We design and build so many new products per year, that we were practically forced to build our own boards. It often happens, that before we go to our company automatic assembly lines, we hand build several engineering iterations of the same product.
Obviously, before you hand place SMD components, you must prepare a documentation. What is not that obvious is to print several copies of the same documentation and group the components by coloring, based on the BOM.
We try to group the components in such a way that each colored page deals with a minimum components only. Additionally, on each page we try to have only one component with large quantity, else it is too confusing to use.
If possible, the small components are placed first, and the largest components are on the last page. For very complicated designs, we have one page per component, creating a sort of assembly book. This helps to save a lot of time during assembly.
We used to place the components with tweezers, which is fine. To speed things up, we obtained a nice tweezer replacement: a manual manipulator. Now we have no problem placing small components, like 0402 passives or 0.5mm pitch semiconductors. Remember that popular Kraftwerk song “I am the robot”? That is how we feel when using it.
We place all the components of the same color on all the boards we are building. Most often we build four boards at a time, this strongly depending on the board size. After we place all the components from one colored page onto all boards we are assembling in one batch, we take the next page and do the same, until all components are placed.
If more batches are needed, we finish one completely, put all boards into the desktop reflow oven and only then start working on the next batch. After the assembly we keep the colored paperwork in the project box, in case we will need more prototypes from the same revision again.