Printed Circuits Boards are cleverly designed items that are used to not only connect electronic components but also mechanically support the functions of many electronic devices. The market for bare PCB’s worldwide was valued at $60.2 Billion in 2014 (US). Components are connected and operated by the conductive pathways, tracks or what is known as signal traces which are etched from copper sheets. This connection is made possible by the distinction between the copper sheets and the non-conductive substrate laminated on to the board. The resistance of the board is determined by the width and the thickness of the traces that expose the copper. The use of the board is also considered when inserting the tracks and traces for example some power and ground traces are usually wider then signal traces. The size and capability of these tracks and traces are described as impedance control. PCB Global not only delivers Printed Circuit Boards to your specifications, we can also assist with your impedance control requirements with predetermined layer stack up including track width and spacing recommendations to ensure impedance matching.

FR4 (Flame Resistant 4) is the most commonly used epoxy which is a woven fiberglass cloth impregnated with the epoxy resin. It has good insulation properties with good arc resistance making it very useful to both single and multilayer boards. The copper is laminated onto the FR4, providing a greater distinction of the conductive pathways as previously described that the FR4 has a high insulation effect. Multilayer PCB’s will have multiple layers of materials which will be laminated together. In some cases, multilayer boards may be required to contain a solid copper layer to act as a shield or ‘ground plane’ for power return.

Copper thickness in any single or multilayer PCB will determine the current-carrying capacity of the board. It is preferable to use heavier copper to increase the carrying capacity as well as increase the resistance of thermal strains. 1oz and 2oz copper are the preferred and more common choices for many single and multilayer PCB’s. Chemical etching is a process using lead and tin to electroplate the copper to increase the thickness. This is achieved by a mixture involving either ammonium persulfate or ferric chloride. The purpose of the chemical etching is to etch away the excess copper on the areas that should not contain copper. The solder, tin, gold or nickel used to plate the PCB acts as a corrosion resistant coating/barrier. The most common method is hot air solder levelling or HASL.

Components such as resistors, capacitors and active devices are usually soldered onto the bare PCB. In some cases, more advanced PCB’s will have their components embedded in the substrate. This offers greater connection and conduction, advancing the function of the loaded PCB. Components embedded throughout different layers of the PCB are made possible by the connection of vias. Multilayer PCB’s in this case will always allow for a higher conduction through component density. In the case that the board does not have any embedded components as described above, the more correct terminology for this item is know as a Printed Wiring Board (PWB) or Etched Wiring Board. It is common for the PWB to be known as a Printed Circuit Board or PCB.

Through-hole technology is the method commonly used to mount electronic components by leads on the boards. The components are soldered onto the copper traces usually on both sides of the board. The soldering can either be done manually or by a wave soldering machine which increases the efficiency. Surface mount technology (SMT) is another method by which the components were redesigned to enable more efficient soldering on the PCB rather then passing wires through the board. This also allows for smaller PCB assemblies and enables a higher density of circuits. PCB Assembly is also known as ‘PCBA’. Assembled PCB’s can be very sensitive to static therefore is placed in anti-static bags during transport to their destinations. When handled, the person must be earthed as the accumulation of static can damage or destroy the components.

Contact the team at PCB Global or proceed to the online quote page for your free and instant quotation today!

PCB Global offer 1 layer, 2 layer and 4 layer Aluminium Printed Circuit Boards online with 1W/m-K and 2W/m-K dielectric as standard options

At PCB Global, we offer a range of Solder Mask colour options such as green, blue, purple, red, yellow, white, black matt and black gloss as well as the option to have no solder mask. These options apply to our FR4 (2-20 layer), Full Spectrum (1-40 layer) and Aluminum Printed Circuit Boards.

Once you have decided on your design of your Printed Circuit Board you need decide on options that will suit your requirements for your board. One of the options is the choice to have a solder mask and/or silkscreen legend. Why not deviate from the standard green printed circuit board and pick a color that will match your corporate logo?

It is important, even for your prototype PCB’s to have a solder mask and silkscreen legend for many reasons. Without the solder mask, your board would be plain copper, or what is known as a bare board with Tin Plating (tin, lead and usually a silver mixture). The Tin plating is placed on the bare board to allow soldering to take place and also slows down the rate of oxidation in the copper.

Today the Solder Mask application is LPI (Liquid Photo Image), which is applied to the production panel in a silkscreen printing process one side at a time. It is then dried in an oven and then the solder mask film is aligned to the pads and bared in an UV exposing machine then placed in a conveyorised developer to remove all the areas (SMT pads and holes) that will be required to have the surface finish applied later like HASL, Immersion Gold, OSP, etc.

The solder mask is a coating that protects the circuit from electrical shorts and corrosion as well as providing electrical insulation, allowing higher voltage traces to be placed at a closer proximity to each other. The most important function of the solder mask is to keep the solder on the pads, which will reduce the formation of bridges or unintended connections. In some cases, such as wave soldering, solder masks are a critical element of this process whereas in other cases, it enables a more efficient and more accurate hand solder job as the solder covers the entire board except for the pads. The colour of the solder mask is not vital to the function of the board, rather providing a distinctive colour to your design and enabling better visibility to your copper connections. There is an option to have a partial solder mask that will cover a specified part of the pad, rather then exposing the entire pad.  This would be ideal if there is a pad underneath a chip, leaving the pad exposed and vulnerable to solder bridges.

Exposed vias are usually covered with the solder mask and silkscreen as this will provide protection from corrosion and electrical shorts while also providing a larger surface area. If a board does not contain a solder mask, it is not an issue, it will mean that care must be taken when soldering as the solder mask reduces cost of mistakes and time taken to complete the solder and components.

Physical and Electrical Properties of the LPI Solder Mask Include:

Next comes the option for the Silkscreen layer which is also called a ‘legend’ as this is a non-conductive ink used to place traces on a board as a means of instructions. It is utilised as a pathway to allow multiple traces and pathways, as this will not be conductive in the copper layers alone as the copper traces would interrupt the circuit. This also makes better use of the space on the board and provides a better contrast for a faster assembly. For prototype PCB’s the silkscreen is usually restricted to the top part of the board but in some cases it can be placed on both sides of the board if required.

PCB Global was created to minimize time taken in waiting for quotes and orders to be processed. We utilise these processes by adding you, the designer and engineer, to quote and order PCB’s to your specifications 24/7, 365 days a year, allowing you to test or create your product for your needs at a faster rate. 

One very important aspect of recent technological innovations involves the introduction of Rigid Flex Printed Circuit Boards in various high technology applications. Rigid Flex PCB’s are Printed Circuit Boards that are composed of various rigid areas along with various flexible areas. The rigid areas provide durability of the board while the flexible areas provide adaptability to the application of the board. Because of the PCB’s semi-flexible nature, it is commonly used in various military and medical electrical equipment.

Rigid flex PCB’s are made out of a combination of different materials, compared to standard non-flex PCB’s. The rigid areas are comprised of FR4 material, while the flexible areas are made from PI or PET. The connection joining the rigid to the flex is made up of epoxy or resin that allows for flexible and adaptable movements. Advantages of rigid flex PCB’s go beyond its adaptable shape, it is also highly resistant to temperature, resistant to static interference and is chemically stable.

The flexible boards are known as passive wiring structures, which are used to interconnect electronic components like integrated circuits, resistors and capacitors. In the consumer electronics industry, flexible circuits are used in cameras, personal entertainment devices, calculators and exercise monitors.

There are a large number of types of flexible circuits used in many various electronic devices. Some of which include; single-sided flex circuits, double access or back bared flex circuits, sculptured flex circuits, double sided flex circuits, multilayer flex circuits, polymer thick film flex circuits and not to forget, the most versatile to use, rigid flex circuits. Rigid flex boards allow integrated interconnection between several rigid structures. This technology allows the reduction in the required number of soldered joints as well as plug in connections along with the number of cables and wires required which reduces complication and increases quality and reliability.

The rigid flex printed circuit boards have many advantages over rigid PCB’s, but the main advantage is the maintenance of strong interconnections that are physically connected, rather then two separate entities that increase the strength of the connection whilst minimizing the space taken up by the board. The costs associated with producing the rigid flex boards are high as the processes in between each step of production, such as soldering and testing, are lengthy and must be done with great care.

There are two kinds of rigid flex PCB’s; one is a Semi-flex board and the other is a Multi-flex board. The semi-flex board is a lower cost option where the flexible areas consist of thin FR4 material, highly suited to a board created with a small number of bends. On the other hand, the multi-flex board consists of a polyimide film coating the entire surface of the board, flexible areas and rigid areas alike, suitable for applications that only require a small bend.

The multi-flex boards are known as hybrid designs as they are comprised of both rigid and flexible substrates by which the electrical interconnections between each layer are made through metal-plated vias, plated through-holes (which go through both rigid and flex areas) and/or micro-holes. Multi-flex boards allow both the rigid and flexible layers to be electrically connected by plated through holes. 

Multi-flex boards have a range of stack-up possibilities that provides the designer/engineer with a greater freedom when designing and selecting materials. There are two basic designs, which are commonly utilised in multi-flex boards; asymmetrical and symmetrical. The asymmetrical layer stack-up is the simplest form of any multi-flex board where the flexible material is placed on one side, and the rigid material is placed on the opposite side of the board; hence the term ‘asymmetrical’ as both sides are presented with different material. The stack-up on asymmetrical multi-flex boards is not limited to only single layers, as it can contain multi-layers. The amount or frequency of copper deposited when plated-through hole will determine the overall flexibility of the finished product. Designers/engineers must take this into consideration when designing a rigid flex board as well as considering the ‘conductivity’ when applying copper to the design. Multi-flex boards with asymmetrical layer stack-ups are relatively easy and cheap to produce.

When the flexible base is located between the two rigid layers, this is called a symmetrical layer stack-up in the multi-flex board. The flexible layer can be pre-fabricated according to the designer’s specifications. The conductive patterns of the middle flexible layers are selectively protected by the coverlays (which is a dry film solder mask) that must match the rigid exterior conductive patterns, forming a good registration of stack-up. Due to the symmetrical building and distribution of materials, the stack-up technique provides a higher mechanical and thermal stability as well as allowing a very high layer-count rigid flex board to be produced.

In respect to component assembly the rigid flex printed circuit boards can be handled and treated with the same production methods as per standard rigid printed circuit boards including being set up as a panelized production panels for assembly through SMT process ensuring efficient productivity.

PCB Global have supplied Rigid Flex Printed Circuit Boards up to 10 layers for many applications in Medical, Communications, Defense and Automotive just to name a few and has supplied customers with these applications all throughout Europe, USA, Australia and India.

For a fast quotation for all your Rigid Flex PCB’s requirements please email your design file to sales@pcbglobal.com, as these PCB’s are currently out of the spectrum of our online capabilities, however, quotations for standard rigid PCB’s up to 20 layers and Aluminum PCB’s up to 4 Layers please visit our web site www.pcbglobal.comfor an instant online quotation.

Our online capabilities include the standard 2 to 20 layer PCB’s, FR4 TG130/140, FR4 High TG=170, Thickness 0.8mm to 3.2 mm, Copper Finish 1oz - 2oz – 3oz & 4oz, Surface Finish - HASL Leaded and ROHS HAL - ENIG Immersion Gold with various solder mask and component legend colours. These qualities, among with our rapid rigid flex quotations, are unique to PCB Global as we have found no other online PCB manufacturer can offer these specifications or services in such a prompt lead time. PCB Global can offer a complete line of products and services from Standard, Fast and Express Quick-Turn Prototype manufacturing, low to medium volume pre-production to high volume mass production services, all at the click of a button!

Multilayer Printed Circuit Boards are made up of two or more PCB’s, which are stacked together to create a reliable mutual connection between them. The way Multilayer PCB’s are constructed is to allow for a much higher component density meaning better conduction and connection. There are at least three conductive layers in one multilayer PCB with the two outside layers and the one layer synthesized and encapsulated by the outer insulation. It is due to the complex manufacturing procedures and lower production volumes that the cost for multilayer PCB’s are generally quite high.

Multilayer PCB’s are used in many basic and complex electrical items, depending on the amount of layers required and used. Most of the basic items require 4-8 layers and the more complex electronic equipment with high speed circuits require above 8 layers, usually 8-40 layers. These boards are typically utilised for professional electronic equipment such as computers and military equipment. The number of layers on a multilayer PCB is identified as the number of separate conductor patterns, which are usually an even number and includes the two outer layers.

The process of manufacturing multilayer PCB’s starts with the Front end tool data Preparation, whereby the engineer or designer prepares his/her layout on a Computer Aided Design (CAD system) which uses their own internal data format, later extended into a Gerber File. The Gerber Files provide information for the copper tracking layers required as well as the solder mask and all other various options for the board.

Once the Factory has established a final confirmation from the designer, Photo tools are created by a Photo plotter, which provides an image of the PCB’s. This image provides information for the machines to print the inner layers. The inner layers are created with an epoxy resin, Laminate, and comprised of a core of glass fiber which includes copper foil pre-bonded to each side of the resin.

The next step involves using a powerful alkaline solution to dissolve or ‘etch’ the inner layers to remove the unwanted copper as per requirement. The inner core areas of the multilayer PCB is now complete. Next the required holes are punched in to meet and align the inner layers to the outer layers. This process is known as the Register Punch and Automatic Optical Inspection (AOI).

After the required holes have been created, it is now time to bond all the layers together and then move into drilling the PCB. The holes for leaded components are drilled as well as the ‘via’ holes that connect the copper layers together. An x-ray drill is used to locate these previously created ‘target holes’. The via holes described here are holes that penetrate the whole board. In the case of many multilayer PCB’s, when the design does not penetrate the whole board, to utilise the space of certain layers for other circuit patterns, ‘Blind’ and ‘Buried’ Vias are used. Blind Vias connect at least one of the inner layers with one of the surface layers without penetrating the whole board, while Buried Vias only connect to inner layers so they are impossible to see.

The next step involves plating, using a chemical deposition of a very thin layer of copper to cover the inside of the holes drilled. The outer layers are imaged to ensure that there are no short circuits in the board. The boards are then electroplated with copper and then they are checked to ensure there is a good electrical connection.

The outer layers are then etched, to remove any excess and unwanted copper. To protect the ‘wanted’ copper, the areas required will be coated with Tin as a protective barrier. After this process, the solder mask is printed on to each side of the board to protect the copper surface and prevent the solder from short-circuiting between components during the assembly. A solderable surface finish is applied to the copper for protection until the components have been soldered onto the board.

If the board requires edge connectors, gold is electroplated onto the board with protective tape placed above the connectors to protect the rest of the board. A silk screen provides an image of the legend to where the components will be place and this is placed on the board. Every multilayer board is electrically tested with a flying probe tester to ensure that there are no open circuits or any areas of short circuits.

The final stage before the final inspection is to profile and cut the PCB’s out of their production panel or as per request of the customer, it can be ‘V-Cut’ on a scoring machine to partially cut the boards out. 

PCB Global is the only manufacturer in the world that can supply 4 layer to 20 layer Printed Circuit Boards On-line with the fastest manufacturing lead times with our Express Delivery Service as listed below;

LAYERS                     EXPRESS Delivery

4 layer                        2 working days

6 layer                        3 working days

8 layer                        4 working days

10 layer                      4 working days

12 layer                      5 working days

14 layer                      5 working days

16 layer                      5 working days

18 layer                      6 working days

20 layer                      6 working days

Our online capabilities cater for the above 4 to 20 layer Printed Circuit Boards, FR4 TG130/140, FR4 High TG=170, Thickness 1.6mm to 4.8 mm, Copper Finish 1oz - 2oz – 3oz & 4oz, Surface Finish - HASL Leaded and ROHS HAL - ENIG Immersion Gold with various solder mask and component legend colours. These qualities are unique to PCB Global as we have found no other online PCB manufacturer can offer these specifications or services in such a prompt lead time. PCB Global also offer a complete line of products and services from Standard, Fast and Express Quick-Turn Prototype manufacturing, low to medium volume pre-production to high volume mass production services, all at the click of a button!

For a fast quotation for all your standard PCB’s up to 20 layers please visit our web site www.pcbglobal.comfor an instant online quotation.