The board is then run on a conveyor belt through a machine that has a wave of molten solder that the board must pass through. This process requires the thru-hole parts to be inserted into their drilled holes and surface mount parts glued to the board over their solder pads. There are two main methods of soldering components onto a production build circuit board, with the first being wave soldering. The image of a solder mask layer within a PCB CAD system Paste Mask and Circuit Board Assembly Wave Soldering Next, we’ll take a look at the paste mask, its role in PCB assembly, and see how it differs from the solder mask. It is also important for solder mask materials to be applied at their correct thickness to ensure even application and optimum curing. For instance, prototype circuit boards may be red while green would denote a regular production unit. Solder mask is often green but can be applied in other colors for those OEMs that desire different colored circuit boards for identifying different production steps. Resins are typically used for solder mask materials due to their resistance to high temperatures, humidity, and solder. This exposure hardens the solder mask material across the board while the unexposed material on the holes and pads is washed off. The circuit board is then exposed to ultraviolet light, except for those pads and holes to be soldered. Photoimageable: Solder mask photoimageable material can be applied either as a liquid or laid down as a sheet of dry film. Liquid: Using a screen printing process, solder mask material can be applied directly to the board, which will harden, leaving the solder pads and drilled holes exposed. The solder mask material can be applied to the circuit board through two different processes: The solder mask barrier between two exposed areas of metal will also help prevent solder from bridging between the open areas and accumulating on a metal surface. This covering will protect the board from the contamination of metal oxidation, corrosion, dirt, and even human contact. Solder mask will cover the entire surface of the circuit board, both metal and dielectric materials, except for the pads and holes that will be soldered. Solder mask, or solder resist as some fabricators refer to it, is a protective material applied to the exterior surfaces of the circuit board. However, before the board is sent to the assembler, another step must be completed to help protect the board: apply the solder mask. Ultimately, all of these layer pairs are composited together into one multilayer circuit board, the holes are drilled, and the finished board is then ready for the assembler to install electronic components. This same basic construction is used for the layer pairs of multilayer circuit boards, except that the copper and dielectric materials are thinner and don’t include the solder pads on the inner layers. To fabricate a double-sided circuit board, dielectric core material is sandwiched between two layers of copper connections consisting of component solder pads, area fills, and connecting traces. Solder Mask and Circuit Board Fabrication paste mask and detail what PCB designers need to know when working with these layers in their circuit board layouts. This article will look at the differences between the solder mask vs. Setting up your PCB CAD system for both solder mask and paste mask layers.Ī laser-cut stainless steel solder paste stencilĪ standard printed circuit board typically requires two different types of layers, referred to as “masks.” Even though they are both referred to as mask layers, solder mask and paste mask layers are required for two completely different parts of the PCB manufacturing process. Understanding the role of solder paste on a PCB.
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