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Advantages of an automated SMT PCB Assembly manufacturing process The process of prototype PCB Assembly requires multiple phases and a large number of steps. The process starts with the specification of the design, then proceeds through electrical design (normally done with a schematic or similar symbolic notation), into the physical design (layout), PCB fabrication themselves, and finishes in the assembly of these boards. Errors and mistakes can be induced at any one of these steps.

With the increase in the number of electronic components available only in SMT PCB Assembly packages, mounting skills, at least for prototypes, will continue to move away from the realm of hand or through-hole assembly.

Hence machine-based SMT PCB assembly is increasingly becoming a requirement. However, purchasing a pick‐and‐place machine is cost prohibitive. And even with pick-and-place equipments, there is still the need to stencil the application of solder paste prior to placing all electronic components.

The Electronics Assembly Process:

Apply Solder Paste: in order to start the assembly process, solder paste needs to be added to those areas of the unpopulated circuit board. Solder paste only goes where a component must be in electrically conductive contact with a metal landing pad on the board itself. Typically, this can be achieved with a Solder Stencil. Using the solder screen placed directly onto the PCB and fixed in the correct position, afterwards a runner is moved across the screen squeezing a small amount of solder paste through the holes in the screen and onto the circuit board 16 layer PCB. As the solder screen has been generated from the printed circuit board files, it has holes on the positions of the pads, and that way the solder is deposited only on the designed solder pads.

There are two basic types of solder stencils: framed stencils for use with the solder paste machinery, and prototype stencils for hand-mounted prototype PCB assembly of the solder paste.

Pick-and-Place Components: Pick-and-Place can occur either by machine or by hand. With hand pick-and-place, a technician uses tweezers to arrange each component on top of the appropriate bits of solder paste. By the other hand, with machine pick-and-place, a machine loaded with components picks the components and places them onto the circuit board. The tension of the solder paste is enough to keep the components in place.

Heat/Reflow Solder: After components have been added to the PCB, the next stage of the mounting process is to pass it through the wave soldering machine. Especially for PCB Assembly prototypes, reflow soldering is the most common technique.
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