13. August 2015

Coax

PCB Connection Techniques

for Coaxial Connectors

Connectors are being used for an increasingly wide area of applications and are therefore becoming more compact and complex. The connections to the printed circuits boards (PCBs) are also being faced with increasingly great challenges. Below we present four different PCB connection techniques that are used at Telegärtner.


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Various Telegärtner PCB plug connectors on a demo board

Through Hole Technology (THT)

In the through hole technology, wired electronic components or components with termination pins are used which are plugged into the PCB by through contacting and soldered on one side (conventional manual soldering, wave soldering or selective soldering). The pitch describes the centre distance between two pin connections of the components and therefore defines the space requirement for the soldering.

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Although SMT (Surface Mount Technology) is used increasingly often, there are still a lot of applications in which standard components for the through hole technology must still be used because of the required current-carrying capacity, component sizes or the high mechanical load of the components themselves (e.g. plug connectors, larger switches, larger electrolytic capacitors, power coils and power semiconductors).


Connectors for through hole technology

Surface Mount Technology (SMT)

Nowadays more than 95% of the components on the PCB are installed using Surface Mount Technology with 20% of the total soldering costs through automation. Therefore all PCBs for mass-produced devices are mounted preferably with SMT.

Printed circuit boards are printed with a solder paste, usually in template printing, on which the components are then mounted. This saves the PCB manufacturer the trouble of drilling contact holes and at the same time enables double-sided assembly of the PCB because both sides of the PCB can be used. But holes cannot be dispensed with completely because they are required for through contacting to the electrical connection of the different layers.

Further advantages in addition to the cost saving are the considerable increase in the component density on the PCB and maximisation of the product quality because humans as a source of error are ruled out by automation.

Edge-Mount Technology

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Telegärtner Karl Gärtner GmbH also offers space-saving connectors with Edge-Mount technology with which RF signals can be transmitted on printed circuits. In this method of installation, the connection only protrudes by a few millimeters and therefore allows a flatter assembly of the terminating devices (e.g. mobile phones). The Edge-Mount connector is soldered onto a recess at the edge of the PCB in SMT and therefore it is practically in the PCB. A straight jack can then be plugged horizontally to the PCB.

 


MMCX Edge-Mount plug connector in SMT soldered onto the PCB.

Press-Fit Technology

In the press-fit technology, the connecting pins of the components are pressed into a metallised and plated drill hole by force. Press-fit connections are known for their robustness and fail safety, also the PCB is not thermally stressed by the press-fit process and enables the manufacture of gas-tight connections without the use of screws, rivets or solder.

Press-fit technology is the most economical solution for numerous applications and often the only one when traditional soldering is no longer possible. At the same time this reliable connection technology allows easy replacement of components by pressing out, usually even repeatedly.

 

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A distinction is made in press-fit technology between solid pins and flexible or elastic pins. With the solid version, the PCB is deformed by the effect of force in the area of the hole, this enables an electrical connection between the sleeve of the PCB and the press-fit contact. The flexible press-fit pins are available in different variants depending on the manufacturer. The press-fit contact is pressed together so that the tension creates a connection for the press-fit contact.

To ensure the connection quality, the PCBs manufactured using press-fit technology are often subjected to automatic optical inspection (AOI). The press-fit process is therefore considered very reliable and visible without the PCB having to be destroyed in the inspection process.

 

Different RF connectors with press-fit connections.


However, it generally applies that PCBs often have mixed assemblies. This achieves technical advantages but at the same time the degree of automation is reduced and this usually generates additional costs.

Telegärtner's staff will be glad to answer any further questions that you may have.