How can double sided pcb manufacturer enhance pcb reliability?2020-04-01
Dominant features of Double sided printed circuit boards
Double sided pcb manufacturer role in electronics
Double-sided printed circuit boards are those boards that consist of one ball of PCB coated with a layer of copper foil on both sides. This type of board is much more difficult for double sided pcb manufacturer compared to a single-sided board.
But it allows to increase the density of the installation of electronic components, as well as trace the conductors without the use of jumpers. Also, a double-sided printed circuit board allows the installation of components on two sides.
All this helps to reduce the length of the conductors and the overall dimensions of the future product.
The creation of double sided pcb
The creation of a double-sided printed circuit board is carried out in specialized CAD programs that help the engineer make the wiring of the conductors as efficiently as possible, check all the necessary gaps, etch the mounting holes and grooves. Make design documentation for future board assembly.
Double-sided printed circuit board in comparison with a single-layer has more space for radio elements. Therefore, in the transition from the upper conductive layer to the lower, it is necessary to carry out electrical communication. For this, double sided pcb manufacturer use metallized.
The main advantages of double sided pcb are:
- reduced overall dimensions of the board and the device as a whole;
- reliability of soldering output elements;
- the ability to solder SMD components from two sides;
- the ability to duplicate power tracks;
- lack of layer separation during prolonged heating.
Today, double-sided printed circuit boards are leaders in the common market, as they have a number of advantages that completely cover the increased cost of their manufacture.
“One of the major contributions at present is to enhance the performance reliability of pcbs. This is because pcb boards are used in almost all sectors of the national economy, and the need for them is constantly growing.”
Furthermore, outstripping the pace of development of microelectronics requires a continuous increase in their technical level. It is determined by an increase in the density of installation of electronic products, increased requirements for reliability, and an increase in the pulse repetition rate. Ensuring these requirements depends on advances in the design and development of double sided pcb manufacturer manufacturing technology.
What is double sided pcb?
Double-sided printed circuit boards (DPP) have a conductive pattern on both sides of the dielectric base. The electrical connection of the layers of the printed circuit is carried out using plating holes.
Similarly, Double-sided PCbs have an increased density of installation and reliable connections. They are used in measurement technology, control systems, and automatic regulation. The location of the printed wiring elements on a metal base allows you to solve the problem of heat dissipation in high-current and radio transmitting equipment.
What is the difference between single and double sided pcbs?
Single-sided circuit boards
Single-sided circuit boards are very cheap to manufacture. The few work steps allow production in rush service in a few hours. By choosing materials such as CEM 1, the price can be reduced even further. Single-sided printed circuit boards are mainly used for mass products, simple circuits or currently in connection with an ALU core (for heat dissipation) in the LED area.
Double sided pcb manufacturing
The manufacturing process of double-sided circuit boards, as well as single-sided ones, is part of a more general process for manufacturing multilayer printed circuit boards. However, for the manufacture of single and double-sided boards, many operations are not used, technologically they are much easier to manufacture, which favorably affects the production time and price.
At the same time, the high design standards of double sided pcb manufacturer “conductor / gap”, allow the use of such boards for the manufacture of a wide range of modern products, they are quite suitable for installation in holes, and for surface mounting.
Production of two-layer printed circuit boards according to the combined positive method (semi-additive method)
Double sided pcb Workpiece Drilling
The initial point in the production of single-layer and double-layer pcbs is hole drilling. Moreover, with multi-layer pcb boards, everything is more complex.
When designing a double-sided printed circuit board, it is necessary for double sided pcb manufacturer to remember that during installation and soldering of components on the board, in the places of contacts where conductors (tracks) are suitable on the mounting hole on both sides, the component contact must be reliably soldered to the tracks on both sides.
This condition can also be fulfilled if the hole is metalized. At home, the metallization of the holes of the printed circuit boards seems impossible.
Therefore, in the amateur radio environment, the holes of the printed circuit boards are made in the usual way (by drilling) without metallizing the walls, but when mounting the parts on the board, their output, if necessary, is soldered to the board conductors on both sides.
How does double sided pcb manufacturer holds an electric test?
The creation of automated control systems for printed circuit boards depends on the tasks that are supposed to be solved with their help. Moreover, the rejection criteria can be multiple in their depth. But basically, double sided pcb manufacturer divide it into three categories:
- conformity or inconsistency of the mounting connections to a given electrical circuit (functional control);
- compliance or non-compliance of the installation parameters with the standards established for them (parametric control);
- sufficient or insufficient reliability of printed circuit boards (diagnostic control).
It should be borne in mind that visual inspection in appearance has the properties of diagnostic control, since it allows you to detect defects in the base, weakening of conductors, ring cracks in the holes and others, which is often difficult to detect by electrical control.
Disadvantages of visual control: the subjectivity of a person’s perception of certain external signs of defects, the greater likelihood of errors and omissions of defects, the inaccessibility to observe the compounds in the structures of the MPP – led to the introduction of automatic controls.
Principles of contacting with tested boards
Electrical testing of printed circuit boards is an important production step and includes two types of tests:
§ integrity test;
§ disunity test.
These tests allow you to test circuit boards for open circuit, short circuit and correct topology.
What are some dominant features of double sided pcbs?
Double-sided printed circuit boards have a conductive pattern on both sides.
The electrical connection is via metal holes.
The main mounting characteristics of two-layer printed circuit boards:
- the number of mounted microcircuits, detachable connectors, resistors, capacitors, etc
- Moreover, the number of combined conclusions of electronic and electrical components;
- chip footprint;
- the pitch of contact pads for attaching microcircuit pins;
- type of mounting of component leads (surface mounting, mounting in holes);
- Simultaneously, placement of contact pads for the installation of repair conductors;
- placement and shape of special reference marks for the automated combination of microcircuit pins and pads;
- placing components on one or both sides.
The main structural characteristics of two-layer printed circuit boards
- board working field size;
- board thickness;
- the amount of mutual misregistration of the layers;
- step through vias;
- size of through vias;
- dimensions of conductors and gaps;
- the thickness of conductors;
- the topology of conductors and interlayer transitions;
- contact pad topology;
- the material of conductors;
- insulation material;
- form of contact pads for surface mounting of components;
- the ratio of the thickness of the board to the diameter of the through hole;
- difficulty level.
Double sided pcb manufacturer use double-sided printed circuit boards for a wide range of modern products of household appliances, instrumentation, and special purposes. Such a wide distribution is explained by less labor costs in the design and layout of printed circuit boards and a simpler manufacturing technology compared to multi-layer printed circuit boards.
What are metalized boards?
Metalized boards, on the other hand, are elements whose holes for connecting the layers are metalized, that is, covered with a thin layer of foil to increase strength without loss of data transfer quality.
At the same time, the compactness of the arrangement of elements on the board is maintained. Therefore, at present, in the production of simple electronic devices and mechanisms, it is used double-sided metalized boards.
Double sided pcb designs
Double sided pcb manufacturer carries the design of all printed circuit boards using special programs in compliance with existing norms and rules. Moreover, the design of this element should be carried out in strict accordance with GOSTs, while any printed circuit board is designed according to the scheme below:
- Preparatory stage
This stage begins with the transfer of the graphic scheme to the database of the computer-aided design system. Next, the location and diagrams of all components are introduced, and in most cases, ready-made libraries are used, since most of the components are standard.
And at the end of this stage, the necessary characteristics of the future element are specified: material, number of layers, hole sizes, and so on.
First of all, all the elements of the board are drawn both individually and as part of a single scheme with all the connections and transitions. At this stage, the designer tries to place all the elements on one side, since otherwise, the production of the board increases significantly in price. And the final (most important) stage is to draw all the tracks and check their performance. These actions are usually carried out several tens of times until the maximum possible accuracy is achieved.
That is, recording the file in a suitable format and compiling a cover note in which all the parameters of the circuit are indicated.
Double sided pcb manufacturing
There are two ways a double sided pcb manufacturer create printed circuit boards:
In the first case, the foil pattern is applied on the board chemically, in the second – on the contrary, at first, the surface is covered with a layer of foil, then unnecessary places are removed from it. Currently, only the second method is used, since using it you can achieve maximum accuracy of the picture.
The production process of printed circuit boards of any type consists of several stages:
- Workpiece production.
- Preparation of the workpiece by degreasing it and cleaning the surface to remove all types of debris and grease from the surface to achieve maximum quality of the future coating.
- Protecting the workpiece.
This stage is the most important for double sided pcb manufacturer since the quality and durability of the future board depends on it. Moreover, this can be done manually or using a special laser printer. The first method is suitable only for a small amount of work since this process is quite time-consuming.
When applying the second method, maximum accuracy is achieved in a minimum time, therefore, it is exclusively used on an industrial scale.
- Removing excess copper and protective coating from the workpiece.
- Drilling holes and processing the workpiece to achieve the necessary electrical properties.
Chemical, mechanical or laser patterning is possible
- Installation and fixing of all components.
- Checking the health of the item.
The last stage is quite important for a double sided pcb manufacturer since it is necessary to check all the characteristics of the finished element. Indeed, having missed at least one, the final device will not work correctly. The check takes place using a stand with a camera in several stages:
- Checking the pattern and location of the holes.
- Inspection of the quantity and correctness of applying solder paste.
- Correct arrangement of elements on the board.
- Soldering quality control.
Ways to reduce the cost of double sided pcb manufacturing
Modern automated production allows to minimize the cost of manufacturing MPP, thanks to double sided pcb manufacturer and the following methods:
- An exception to an overly complex project. The avoidance of a large number of layers and conductors is intended.
- Unreasonable use of a large number of multiple types of blind and hidden holes is not allowed.
- A structure with internal cores are used (if you use external cores, the number of layers increases, which means that the cost increases).
- The combined structure is used only when necessary.
What should be the optimal distance between the elements on the printed circuit board?
Of course, for double sided pcb manufacturer, there is no maximum recommended distance between the components on the printed circuit board – the more the better. However, some projects require the densest possible placement of components on the printed circuit board, so often you have to find some compromise.
How should components be placed on a double sided pcb for mounting?
When using wave soldering or flash brazing technologies in SMD convection ovens, the components should be oriented in the same direction, if possible. For boards in which one of the sides should be soldered by a solder wave, the preferred orientation of the components
In which grid should the components be placed on the double sided pcb board?
For projects using traditional output mounting components, double sided pcb manufacturer recommends a 2.54 mm (100 mils) grid. For denser placement, when using a surface mount, the placement grid can be reduced to 1.27 mm (50 mil) or even 0.63 mm (25 mil). The use of a finer mesh is often unjustified.
Which PCB mounting is better: double-sided or single-sided?
It is necessary to distinguish between two-sided mounting of components on a printed circuit board and one-way. Double sided pcb manufacturer should try to place all components on one side (the “main” side) of the circuit board. Otherwise, this will entail a rise in the cost of mounting printed circuit boards.
What are Fiducial Marks and what are they used for?
Double sided pcb manufacturer use these signs as an autonomous coordinate system, available on every printed circuit board. And necessary for equipment at all stages of the production of printed circuit boards and subsequent installation. Similarly, they allow the equipment to correct the measurement errors of the current coordinates that accumulate during their installation.
There are two types of signs: general and local
– Common reference marks are used for the entire printed circuit board or in case several printed circuit boards are combined in a panel.
– Local reference marks are used to bind a specific component (usually with a large number of pins and a small pitch between them).
How to lead conductors to the contact pads for good quality soldering of double sided pcb boards?
Wide conductors suitable for contact pads can interfere with good soldering of the elements. Since the heat will “leave” the site along the wide conductor. As a result, the soldering will turn out to be “cold”. Therefore, double sided pcb manufacturer often use narrow conductors, connecting directly the contact pad and a wide conductor.
What should be the mutual arrangement of vias and pads to ensure good quality soldering of elements on a double sided pcb board?
Excessively close placement of the contact pads and vias prevents heat and solder from leaving the contact pad. In this case, the same recommendations are valid for wide conductors.
Currently, it is double sided pcb boards that are most popular. They are able not only to connect all components and provide high-quality signal transmission. But also, to create the most compact device.
And thanks to modern double sided pcb manufacturer technologies. The cost of such boards is not much higher than simple single-layer or two-layer elements. There are no suitable alternatives to printed circuit boards. So they replaced cable connections in instrumentation while creating ideal conditions for both customers and performers.
Unlike single-layer and multilayer boards, double sided pcb boards open up much more possibilities for design. Therefore, they are actively used in the design of complex electrical devices.