Your Operation Could Benefit From Utilising a Quality Management System

Mar 04, 2019  
In electronic devices, printed circuit boards, or PCBs, are used to mechanically support electronic parts which have their connection leads soldered onto copper pads in surface 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 element side, a mix of thru-hole and surface install on the top side just, a mix of thru-hole and surface area install components on the top and surface area install elements on the bottom or circuit side, or surface area install elements on the top and bottom sides of the board.

The boards are likewise used to electrically link the needed leads for each part utilizing conductive copper traces. The component pads and connection traces are etched from copper sheets laminated onto a non-conductive substrate. Printed circuit boards are designed as single sided with copper pads and traces on one side of the board only, double sided with copper pads and traces on the top and bottom sides of the board, or multilayer styles with copper pads and traces on the top and bottom of board with a variable number 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 engraved away to form the real copper pads and connection traces on the board surfaces as part of the board manufacturing procedure. A multilayer board consists of a variety 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 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 common 4 layer board design, the internal layers are often used to supply power and ground connections, such as a +5 V plane layer and a Ground plane layer as the 2 internal layers, with all other circuit and part connections made on the top and bottom layers of the board. Really complicated board styles might have a a great deal of layers to make the numerous connections for different voltage levels, ground connections, or for connecting the many leads on ball grid variety gadgets and other large incorporated circuit bundle formats.

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

The film stack-up method, a newer innovation, would have core material as the center layer followed by layers of pre-preg and copper material built up above and listed below to form the last number of layers required by the board design, sort of like Dagwood constructing a sandwich. This approach allows the producer versatility in how the board layer thicknesses are combined to fulfill the ended up product thickness requirements by differing the variety of sheets of pre-preg in each layer. As soon as the material layers are finished, the entire stack is subjected to 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 many applications.

The procedure of identifying products, processes, and requirements to fulfill the consumer's requirements for the board design based upon the Gerber file information offered with the purchase order.

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

The standard procedure of exposing the copper and other areas unprotected by the etch resist movie to a chemical that removes the unguarded copper, leaving the safeguarded copper pads and traces in location; more recent processes use plasma/laser etching instead of chemicals to eliminate the copper material, permitting finer line definitions.

The process of lining up the conductive copper and insulating dielectric layers and pressing them under heat to trigger the adhesive in the dielectric layers to form a solid board product.

The process of drilling all the holes for plated through applications; a 2nd drilling process is used for holes that are not to be plated ISO 9001 through. Information on hole location and size is included in the drill drawing file.

The process of applying copper plating to the pads, traces, and 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 location however the hole is not to be plated through. Avoid this process if possible because it adds expense to the ended up board.

The process of applying a protective masking product, a solder mask, over the bare copper traces or over the copper that has actually had a thin layer of solder applied; the solder mask safeguards versus environmental damage, offers insulation, protects versus solder shorts, and protects traces that run in between pads.

The process of covering the pad locations with a thin layer of solder to prepare the board for the ultimate wave soldering or reflow soldering procedure that will occur at a later date after the parts have actually been positioned.

The process of applying the markings for element classifications and element describes to the board. Might be used to just the top side or to both sides if elements are installed on both leading and bottom sides.

The procedure of separating multiple boards from a panel of similar boards; this process likewise permits 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 process of checking for connection or shorted connections on the boards by ways using a voltage between numerous points on the board and figuring out if an existing flow happens. Relying on the board intricacy, this process may need a specifically created test fixture and test program to incorporate with the electrical test system utilized by the board manufacturer.