In electronic devices, printed circuit boards, or PCBs, are utilized to mechanically support electronic components which have their connection leads soldered onto copper pads in surface area mount applications or through rilled holes in the board and copper pads for soldering the part leads in thru-hole applications. A board style may have all thru-hole components on the top or part side, a mix of thru-hole and surface area install on the top side just, a mix of thru-hole and surface install parts on the top and surface area mount components on the bottom or circuit side, or surface area install parts on the leading and bottom sides of the board.
The boards are likewise utilized to electrically link the needed leads for each part using conductive copper traces. The element pads and connection traces are etched from copper sheets laminated onto a non-conductive substrate. Printed circuit boards are designed as single agreed copper pads and traces on one side of the board only, double agreed copper pads and traces on the leading and bottom sides of the board, or multilayer designs with copper pads and traces on the top and bottom of board ISO 9001 Certification Consultants with a variable number of internal copper layers with traces and connections.
Single or double sided boards include 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 variety of layers of dielectric product that has been fertilized with adhesives, and these layers are used to separate the layers of copper plating. All these layers are lined up and then 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 normal 4 layer board design, the internal layers are frequently utilized to supply power and ground connections, such as a +5 V aircraft 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 numerous connections for various voltage levels, ground connections, or for connecting the lots of leads on ball grid range devices and other big integrated circuit bundle formats.
There are normally 2 types of product used to build a multilayer board. Pre-preg product is thin layers of fiberglass pre-impregnated with an adhesive, and remains in sheet kind, normally about.002 inches thick. Core material resembles a very thin double sided board because it has a dielectric product, such as epoxy fiberglass, with a copper layer transferred on each side, generally.030 density dielectric product with 1 ounce copper layer on each side. In a multilayer board design, there are 2 techniques utilized to develop the preferred number of layers. The core stack-up technique, which is an older technology, utilizes a center layer of pre-preg material with a layer of core product above and another layer of core product below. This mix of one pre-preg layer and two core layers would make a 4 layer board.
The movie stack-up technique, a newer technology, would have core product as the center layer followed by layers of pre-preg and copper product developed above and below to form the last variety of layers needed by the board style, sort of like Dagwood developing a sandwich. This method permits the maker versatility in how the board layer thicknesses are combined to fulfill the completed product thickness requirements by varying the number of sheets of pre-preg in each layer. Once the product layers are completed, the whole stack goes through 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 procedure of manufacturing printed circuit boards follows the actions below for most applications.
The process of identifying products, procedures, and requirements to fulfill the customer's specifications for the board style based on the Gerber file information supplied with the order.
The process of moving the Gerber file information for a layer onto an etch withstand movie that is put on the conductive copper layer.
The conventional procedure of exposing the copper and other locations unprotected by the etch withstand movie to a chemical that gets rid of the vulnerable copper, leaving the safeguarded copper pads and traces in location; more recent procedures use plasma/laser etching instead of chemicals to eliminate the copper material, permitting finer line meanings.
The process of lining up the conductive copper and insulating dielectric layers and pushing them under heat to trigger the adhesive in the dielectric layers to form a solid board product.
The procedure of drilling all of the holes for plated through applications; a second drilling procedure is utilized for holes that are not to be plated through. Details on hole area and size is contained in the drill drawing file.
The procedure of using copper plating to the pads, traces, and drilled through holes that are to be plated through; boards are positioned in an electrically charged bath of copper.
This is required when holes are to be drilled through a copper location however the hole is not to be plated through. Prevent this process if possible because it includes cost to the ended up board.
The process 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 applied; the solder mask secures against environmental damage, offers insulation, protects versus solder shorts, and safeguards traces that run in between pads.
The process of coating the pad locations 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 elements have been put.
The procedure of using the markings for element classifications and part describes to the board. May be used to simply the top side or to both sides if parts are installed on both top and bottom sides.
The procedure of separating multiple boards from a panel of similar boards; this process likewise enables cutting notches or slots into the board if required.
A visual evaluation of the boards; likewise can be the process of inspecting wall quality for plated through holes in multi-layer boards by cross-sectioning or other techniques.
The procedure of looking for connection or shorted connections on the boards by ways using a voltage between numerous points on the board and identifying if a present circulation happens. Depending upon the board complexity, this process may require a specially designed test component and test program to integrate with the electrical test system used by the board manufacturer.