bus board with press-in connectors
Solderless termination for connectors has proven to be reliable for decades. Today the use of press-in connectors encompasses all fields of electrical and electronical applications.
bus board with press-in connectors
Pressing of electrical components, mainly connectors, is characterised through the matching of the connector pin and the plated through hole of the pcb. Whereas the desired electrical characteristics can be attained relatively independant from the design of the press-in zone, the mechanical characteristics of the press-in zone are crucial for the reliable assembly of connectors where pcb's have different surfaces.
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Although the scope of requirements at the press-in process is generally defined in time-tested specifications, the novel press-in zones should offer an optimal handling and a reliable termination. Essentially, this is guaranteed through the design of the press-in zone and the meticulous observance of tolerances. HARTING has been using FEM simulations for the calculation and optimisation of press-in zones for a long period of time. This expertise allows us to simulate various pcb configurations, very accurate. |
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The processing of press-in connectors can be divided into 3 phases, containing both mechanical and metallurgical operations:
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1. Centering and placing of the termination pins The centering of connectors before pressing is important in order to prevent damage to the pcb and the termination pins. Centering can be omitted when connectors are pressed using a flat rock die. HARTING offers insert blocks for male connectors to make the centering of connectors unnecessary. a Press
die (Flat rock) |
Phase 1 |
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2. Pressing in the pins In the press-in process the insertion force is continuously transformed into compression force. The resulting friction frees the contacting bars of insulating films. Superfluous plating (tin) is transferred within the plated through hole. A gas- tight connection of fresh non-oxidised metal surfaces is obtained. |
Phase 2 |
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3. Obtaining the final position The press-in operation should be terminated as soon as the connector obtains its final position on the pcb to avoid unnecessary compressive stress. The press-in machines of HARTING feature automatic termination of the press-in operation in dependant of pcb thickness and surface properties. |
Phase 3 |
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The har-press®-zone is based on the industry renowned needle eye technology. Its special design allows for compensation of tolerances of pcb surface properties (e.g. superfluous tin plating). The excessive material is displaced within the plated through hole, whereby a gas-tight and corrosion resistant electrical connection is assured.
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Diameter plated through |
Diameter plated through |
Diameter plated through |
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Cross section of a pbc 2.4 mm thick with various hole diameters |
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Recommended configuration of plated through holes
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Due to the high deformation resistance and resilience of har-press® contacts, they can be easily and repeatedly removed in case of repairs without impairment to their functioning. Today tinned surfaces are widely used as a standard, the pcb technology trends are moving to low tin or tin free surfaces. Cu, Pd, Au and Ag are the important alternatives. Specific parameters and particularly different friction factors of these surfaces make high demands on press-in zones. har-press® is extremely versatile and offers a reliable electrical contact, therefore it is especially well suited for applications with these surfaces. Please contact us for detailed test reports. a) chem. Sn |
Sketch: press-in zone in plated through hole |
Benefits of the press-in technology
Thermal shocks associated with the soldering process and the risk of the board malfunction are avoided.
No need for the subsequent cleaning of the assembled pcb's
Additional wrap connections are made possible by using connectors with long pins
Recommended configuration of plated through holes
The plated through holes of tinned pcb's should have following configuration:
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Diameter of the holes pcb thickness |
0.94-1.09 mm |
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Tin-lead plated |
Hole |
1.15±0.025 mm |
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Cu |
min. 25 µm | |
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Sn |
min. 15 µm | |
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Plated hole |
0.94-1.09 µm | |
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Chemical |
Hole |
1.15±0.025 mm |
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Cu |
min. 25 µm | |
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Sn |
min. 15 µm | |
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Plated hole |
1.00-1.10 µm | |
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Au / Ni plated PCB |
Hole |
1.15±0.025 mm |
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Cu |
min. 25 µm | |
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Ni |
3-7 µm | |
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Au |
0.05-0.12 µm | |
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Plated hole |
1.00-1.10 mm | |
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Silver plated PCB |
Hole |
1.15±0.025 mm |
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Cu |
min. 25 µm | |
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Ag |
0.1-0.3 µm | |
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Plated hole |
1.00 - 1.10 mm | |
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OSP |
Hole |
1,15±0,025 mm |
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Cu |
min. 25 µm | |
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Plated hole |
1.00 - 1.10 mm |
PCB board thickness: > 1.6 mm
Quality assurance press-in process
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Quality control of the press-in termination The press-in force correlates with the diameter of the plated through hole and with the friction coefficient of the surface; therefore it can be used for a continuous monitoring of the process. The retention force, as an indirect measure of the normal force, serves to qualify the process or random tests. |
Typical press-in and retention force for the har-press |
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The automatic press-in machines of HARTING feature a graphical user interface for monitoring the process and the quality of the press-in termination |
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HARTING assists you with the most advanced quality assurance methods beyond the usual scope |
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see also Press-in tools
