PCB terminals and connectors
Surface Mount Technology (SMT) has become established as the common standard for processing electronic assemblies. The connection system can be integrated in the SMT process in two ways: by means of THR (Through-Hole Reflow) or SMD (Surface Mount Device) technology. A combination of both types of mounting is also possible.
Detailed processing information is helpful for product use. We would be pleased to support you with further information on our products.
In the through-hole reflow process (THR), components are inserted through a hole in the PCB and then soldered to other SMT components. The special challenge of this method is that the components need to withstand the high temperatures of the SMT process.
THR product overview
With their short pin length of 1.50 mm, our components free up more space and allow greater design freedom, while meeting the requirements of IPC-A-610 E (7.3.3, Table 7-3, Note 1). With a PCB thickness of 1.60 mm, you benefit from double-sided assembly.
The option of vapour-phase soldering is also available, since no drops of solder paste form on the underside of the circuit board. Our simplified paste application process and minimised paste volumes also reduce your manufacturing costs. The optimum temperature absorption and trouble-free degasing of the flux in the soldering process also contribute to cost-efficient PCB assembly.
We manufacture our THR components from the high-performance plastic LCP to ensure reliable, problem-free use on your printed circuit boards. You can use these halogen-free, high-temperature-resistant components in all common soldering methods and benefit from their outstanding dimensional stability and accurate grid alignment. With their extremely low moisture sensitivity level (MSL 1), you can store the components indefinitely and use them in the assembly process without pre drying. Our components remain dimensionally stable even at high operating temperatures and fit snugly on the PCB.
With a position tolerance of less than ± 0.1 mm around the zero position, our solder pins exceed the requirements of the IEC 61760-3 standard. Due to our advanced manufacturing methods, our high-precision pin connectors are ideally suited for use in automated assembly. The contact pin is positioned and checked with the utmost care. Our dimensionally stable pin headers thus assure you of a seamless THR process without downtimes.
Design und processing recommendations
For particularly fast and stable fixing to the circuit board, you no longer need any additional screws. With our solder flanges, you solder the connection components to the contact pins in a single step in the reflow process. Time-consuming steps involving screws are no longer required. In addition, the geometry and positioning of the solder flange protects the solder joints against long-term mechanical stress and prevents them from being put under strain when screws are tightened.
Reduce the number of items, the time spent on data administration and the storage space required to a minimum. Thanks to their modular structure, our SL-SMarT pin headers with THR solder connections can be combined using any number of two- and three-pin components. Since you only need two conveyor systems, you optimise use of the available feeder space. Especially for circuit boards with different, multi-pole pin headers, the processing rate and cost optimisation achieved with the SL-SMarT are unrivalled.
In the SMT process, the surface-mounted devices (SMDs) are soldered to the PCB with solder pads. The use of SMD components means that it is possible to dispense with wire pins to the components and with the holes normally required for attachment to the PCB.
SMD product overview
To maximise dimensional stability and ensure accurate grid alignment, we make our SMD components from the high-performance plastic LCP. This material offers high dimensional stability and excellent solder heat resistance. Our SMD connection system thus ensures a reliable, smooth SMD process. With their low moisture sensitivity level (MSL 1), you can process our components without pre drying.Their low thermal expansion coefficient also prevents an assembly from being deflected during the soldering process, thus speeding up your fully automated assembly process.
Our LSF-SMD PCB terminals guarantee a secure hold on the circuit board thanks to the use of two solder pads per pole – even without additional mounting flanges. Holding forces per pin of over 150 N in an axial direction withstand even heavy loading. Simulated endurance tests confirm the high vibration and shock resistance of our products according to IEC 61373/10.2011, assuring you of a smooth and maintenance-free SMT process over the long term. Even secure integration on composite boards made of glass, ceramics or aluminium is unproblematic.
Our components with pick-and-place pads and suction surfaces support secure mounting and precise placement in fully automated assembly. With their light weight, our SMD-optimised PCB terminals also maximise assembly performance. You benefit from simple integration of the connection elements in the assembly process with tape-on-reel packaging in standard conveyor widths. They are designed for automation and contain a very high number of components per roll. This reduces your setup costs in automated SMD processes.
To ensure reliable soldering quality in the manufacturing process, the contact surfaces of solder pins must be wetted with the solder paste immediately after assembly. This allows the flux contained within the paste to react with the Sn coating, resulting in a reliable soldering quality. The LSF-SMD has a coplanarity of up to 100 μm. We recommend a stencil thickness of 150 to 200 μm.
Stability properties are covered by normative values as well as additional practical testing. The axial torque per contact point (pole) is significantly higher than the values permitted by the standard IEC 60947-7-4. A clamping force per pole of around 150 N (40 N limit value for 1.5 mm² conductor cross-sections) in the axial direction is many times higher than the normative requirements.
A simulated service life test is performed. The test spectrum includes increased broadband noise and shock in accordance with IEC 61373/10.2011 with a category 1B severity level (“body mounted”) in the 5-to-150-Hz frequency range and with an ASD level of 1.857 (m/s²)²/Hz 3 dB and an effective acceleration of 5.72 m/s² and 240 degrees of freedom (DOF). The test duration is five hours per axis. The half-sine shock wave form has a peak acceleration of 50 m/s² and a nominal duration of 30 ms.
General information (THR and SMD components)
Besides the Standard-Box packaging, Weidmüller offers tape-on-reel, tray and tube packaging for machine compatible and product-specific packaging of components.
For automatic assembly, the male headers are available for 90° (angles) - and 180° (straight) versions in “tape-on-reel” technology. These are developed precisely for the respective product in compliance with IEC 602586-3. The reels are anti-static, have a diameter of 330 mm (specific details are found in the data sheet) and are adapted to commercially available feeders.
The tape is covered with protective foil. A high temperature resistant "pick-and-place pad" is centred on the male header for automatic gripping of the straight male headers (180°). This "pick-and-place pad" included in the delivery package of the males headers in the "tape-on-reel" mode of delivery. The angled male headers (90°) are designed such that no "pick-and-place pad" is required for automatic gripping.
The width of the tape-on-reel is influenced by the pitch size (L1), the number of poles and the side edge (O=open, F=flange, SF=solder flange, LS=lock solder flange). For the universal tapes used, Weidmüller offers the tape-on-reel widths: 32 mm, 44 mm, 56 mm and 88 mm.
You find packaging information (e.g. packaging type, quantity, reel diameter) in the respective data sheet of the selected product and on the product level of the Weidmüller product catalogue.
Our components (THR and SMD) are made of glass fibre reinforced LCP (Liquid Crystal Polymer). This guarantees a high level of shape stability. The positive temperature properties of the material and the in-built pitch space (stand-off) of min. 0.3 mm make it ideally suited for the solder paste process. For data push-in connectors (RJ45 and USB sockets), besides LCP, also PA9T and PA10T are used which also have a low Moisture Sensitivity Level (MSL 1).
Plug-in connector systems are exposed to many external influences, such as damp heat and vibration which have a negative effect on the electrical and mechanical properties and can thus reduce the service life of the device. In order to combat this wear, our plug-in connector components are provided with an effective contact coating and are tested in the lab for long service life under an industrial atmosphere. The typical contact layer structure has a copper alloy as base material, nickel as barrier layer and zinc or gold as the contact layer.
Detailed information on the materials and surfaces are contained on the product catalogue and in the data sheet.
No less essential in the SMT production process is reflow soldering: In this step, an existing solder deposit is melted, whereby around 50 percent of the paste volume vaporises. After the PCB is assembled, a drop forms on the pin tip: it is melted in the reflow profile, flows by capillary action into the drill hole and forms the solder meniscus.
The soldering profile recommended for Weidmüller SMD and THR components describes the characteristic curve and the limits in the process:
PCB and components are gently heated in the preheating phase. This "activates" the solder paste in parallel. During the period above the fusion temperature (217°C to 221°C), the solder is liquefied and connects the components to terminals on the board. The maximum temperature of 245°C to 254°C is maintained for approximately ten to 40 seconds. The solder hardens during the cooling phase. The PCB and components should not be allowed to cool too quickly, however, to prevent stress cracks in the solder.
The recommended solder profiles for reflow and wave soldering are contained in the product catalogue and the data sheet of the respective components.
The required paste volume and therefore the degree of filling of solder paste in the past printing process are essential for an optimal soldering result in the SMT process.For THR solder points - in comparison to the wave soldering - a slightly larger mounting hole diameter is recommended because the fusion of the paste requires sufficient space in the drilled hole.
The rule of thumb for assembly hole diameter (D) is:a. for round or orthogonal solder pins: D = d + min. 0.3 mmb. for rectangular solder pins: D = d + min. 0.25 mm
The recommended soldering terminal diameter (STD) for feed-through solder joints is calculated as follows:STD = D + 2*R
Normally the residual ring width R = 0.3 mm. For THR components, such as plug-in connectors, due to the higher solder joint stability and reparability, a slight increase of the residual ring width to approx. 0.4 mm is recommended.After determining the soldering terminal diameter, the standard stencil layout is used for the hole design. The stencils usually have a thickness of 120 µm to 180 µm. The stencil hole diameter (SHD) in this case is about ten percent less than the soldering terminal diameter.
Soldering technologies – SMD and THR technology
Materials and surfaces – Metals used by Weidmüller
White paper – Trends and technologies in device connectivity
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