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In electronics, printed circuit boards, or PCBs, are utilized to mechanically support electronic components which have their connection leads soldered onto copper pads in surface install applications or through rilled holes in the board and copper pads for soldering the component leads in thru-hole applications. A board design might have all thru-hole parts on the leading or component side, a mix of thru-hole and surface install on the top only, a mix of thru-hole and surface area install parts on the top side and surface area install parts on the bottom or circuit side, or surface area mount parts on the leading and bottom sides of the board.

The boards are likewise utilized to electrically connect the required leads for each element using conductive copper traces. The component pads and connection traces are etched from copper sheets laminated onto a non-conductive substrate. Printed circuit boards are created as single sided with copper pads and traces on one side of the board only, double sided with copper pads and traces on the leading and bottom sides of the board, or multilayer styles with copper pads and traces on the top and bottom of board with a variable variety of internal copper layers with traces and connections.

Single or double sided boards consist of a core dielectric material, such as FR-4 epoxy fiberglass, with copper plating on one or both sides. This copper plating is etched away to form the actual copper pads and connection traces on the board surfaces as part of the board production process. A multilayer board consists of a number of layers of dielectric product that has actually been fertilized with adhesives, and these layers are utilized to separate the layers of copper plating. All of these layers are lined up and after that bonded into a single board structure under heat and pressure. Multilayer boards with 48 or more layers can be produced with today's technologies.

In a typical 4 layer board design, the internal layers are typically used to offer power and ground connections, such as a +5 V airplane layer and a Ground aircraft layer as the 2 internal layers, with all other circuit and part connections made on the leading and bottom layers of the board. Very complex board styles might have a large number of layers to make the various connections for different voltage levels, ground connections, or for linking the lots of leads on ball grid selection devices and other big integrated circuit bundle formats.

There are normally 2 kinds of product utilized to construct a multilayer board. Pre-preg product is thin layers of fiberglass pre-impregnated with an adhesive, and remains in sheet form, typically about.002 inches thick. Core material resembles a very thin double sided board in that it has a dielectric product, such as epoxy fiberglass, with a copper layer deposited on each side, typically.030 density dielectric product with 1 ounce copper layer on each side. In a multilayer board design, there are two methods used to develop the desired variety of layers. The core stack-up approach, which is an older technology, utilizes a center layer of pre-preg material with a layer of core material above and another layer of core product below. This mix of one pre-preg layer and 2 core layers would make a 4 layer board.

The film stack-up technique, a newer innovation, would have core material as the center layer followed by layers of pre-preg and copper material developed above and listed below to form the last number of layers required by the board design, sort of like Dagwood building a sandwich. This method permits the manufacturer versatility in how the board layer thicknesses are integrated to meet the ended up product thickness requirements by differing the variety of sheets of pre-preg in each layer. Once the product layers are finished, the entire stack undergoes heat and pressure that causes the adhesive in the pre-preg to bond the core and pre-preg layers together into a single entity.

The process of producing printed circuit boards follows the actions below for the majority of applications.

The procedure of determining materials, processes, and requirements to satisfy the consumer's requirements for the board design based on the Gerber file information supplied with the purchase order.

The process of moving the Gerber file data for a layer onto an etch withstand movie that is put on the conductive copper layer.

The conventional process of exposing the copper and other areas unprotected by the etch resist movie to a chemical that eliminates the unprotected copper, leaving the secured copper pads and traces in place; newer procedures utilize plasma/laser etching instead of chemicals to remove the copper product, permitting finer line meanings.

The procedure of aligning the conductive copper and insulating dielectric layers and pressing them under heat to activate the adhesive in the dielectric layers to form a strong board material.

The procedure of drilling all the holes for plated through applications; a second drilling process is used for holes that are not to be plated through. Info on hole area and size is included in the drill drawing file.

The procedure of applying copper plating to the pads, traces, and ISO 9001 drilled through holes that are to be plated through; boards are placed in an electrically charged bath of copper.

This is required when holes are to be drilled through a copper area but the hole is not to be plated through. Prevent this procedure if possible since it adds expense to the ended up board.

The procedure of using a protective masking material, a solder mask, over the bare copper traces or over the copper that has had a thin layer of solder used; the solder mask safeguards against ecological damage, provides insulation, safeguards against solder shorts, and protects traces that run between pads.

The procedure of coating the pad areas with a thin layer of solder to prepare the board for the eventual wave soldering or reflow soldering process that will happen at a later date after the components have been put.

The process of applying the markings for component designations and part details to the board. May be applied to just the top side or to both sides if elements are installed on both leading and bottom sides.

The process of separating multiple boards from a panel of identical boards; this process likewise permits cutting notches or slots into the board if required.

A visual inspection of the boards; also can be the process of examining wall quality for plated through holes in multi-layer boards by cross-sectioning or other methods.

The procedure of looking for connection or shorted connections on the boards by methods applying a voltage in between different points on the board and figuring out if a present circulation happens. Depending upon the board intricacy, this procedure might need a specifically developed test fixture and test program to integrate with the electrical test system utilized by the board manufacturer.