PCB assembly requires precision and expertise in every step of the soldering process. Every soldering process requires a specific profile, from the selection of suitable materials and surfaces to setting of parametersrepresented in soldering curves. Our comprehensive product range covers all common soldering processes, including reflow soldering, wave solderingand selective soldering. With our customized solutions, we ensure that your PCBs meet the highest quality standards. You can rely on our experience and our commitment to first-class results in PCB assembly.
Surface mounting technology (SMT) has become a common standard in the processing of electronic assemblies and PCB assembly. The connection technology can be integrated using THR (Through Hole Reflow) or SMD (Surface Mount Device), and a combination of both mounting types is also possible.
Find out more about our THR and SMD components for optimum PCB assembly below.
Through Hole Reflow (THR) refers to the processing of components that are inserted into the PCB and then soldered together with other SMT components for PCB assembly. The special challenge of this method is that the components need to withstand the high temperatures of the SMT process.
Our components with the short pin length of 1.50 mm allow more space and design freedom and meet the requirements of IPC-A-610 E. 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.
Optimum PCB assembly with high-performance plastic: Our THR components offer halogen-free, high-temperature-resistant properties for all common soldering processes. With maximum dimensional stability and grid fidelity as well as a low moisture sensitivity level (MSL 1), they remain dimensionally stable even under high thermal loads and fit snugly on the PCB.
Precise pin headers for optimum PCB assembly: With a solder pin position tolerance of less than ± 0.1 mm around the zero position, they comply with the IEC 61760-3 standard and are ideal for automatic assembly. Our dimensionally stable pin headers ensure a smooth SMT process without failures thanks to modern manufacturing processes and careful control of the contact pins.
Efficient PCB assembly with solder flanges: Fix connection components quickly and securely without additional screws. In the reflow process, they are soldered directly to the contact pins, eliminating the need for time-consuming work steps. The geometry and positioning of the solder flanges protects the solder joints from permanent mechanical stress and prevents stress caused by tightening screws.
Applications where fast processing and reliable and stable connections to the printed-circuit board are of the essence. Reflow, wave, or hand soldering with high temperature requirements.
Surface Mounting Technology (SMT) connects SMD components directly via solderable connection surfaces (solder pads) on the PCB. 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.
Optimum PCB assembly with high-performance plastic: Our SMD components made of LCP offer maximum dimensional stability and grid fidelity. High dimensional stability and resistance to soldering heat ensure a reliable SMD process. With a low Moisture Sensitivity Level (MSL 1), pre-drying steps are superfluous. The low thermal expansion coefficient prevents assembly deflection in the soldering process, which speeds up your fully automated assembly process.
Optimum PCB assembly with LSF SMD PCB terminal blocks: Our terminal blocks offer a reliable hold thanks to two solder pads per pole, without additional mounting flanges. With holding forces of over 150 N in the axial direction, they can withstand high loads. Simulated service life tests in accordance with IEC 61373/10.2011 confirm their high vibration and shock resistance. Benefit from a smooth, long-term maintenance-free SMD process and integrate them securely on composite printed circuit boards made of glass, ceramic or aluminum.
Optimum PCB assembly with our SMD-optimized components: The pick-and-place pads and suction surfaces enable secure pick-up and precise placement in fully automated assembly. The low weight of our PCB terminal blocks also maximizes assembly performance. Use tape-on-reel packaging in standard belt widths for easy integration of the connection elements. Machine-compatible and with a high component density per reel, they reduce your set-up costs in the automatic SMD process.
To ensure reliable soldering quality during PCB assembly, the contact surfaces of the solder pins must be wetted with solder paste immediately after assembly. This allows the contained flux to react with the Sn surface, resulting in reliable soldering quality. The LSF-SMD has a maximum coplanarity of 100 μm. For optimum results, we recommend a stencil thickness of 150 to 200 μm.
The stability properties for PCB assembly are covered by normative values and additional practical tests. The axial tensile forces per clamping point (pole) are well above the standardized permissible values according to IEC 60947-7-4. Retention forces per pole of over 150 N in the axial direction exceed the normative requirements several times over, ensuring a particularly robust connection.
A simulated service life test is carried out for this purpose, which also covers the requirements for PCB assembly. 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.
Subassemblies that are exclusively equipped with SMD components and exposed to medium electromechanical loads.
THR components are fed through holes and soldered, which provides a strong connection and is used for reliable applications. SMD components are soldered directly onto the PCB, which enables more compact designs and is ideal for modern, miniaturized devices. Both methods have their advantages and disadvantages and are used depending on the application.
Besides the Standard-Box packaging, Weidmüller offers tape-on-reel, tray and tube packaging for machine compatible and product-specific packaging of components.
Tape-on-reel
For automatic assembly, the male headers are available for 90° (angles) - and 180° (straight) versions in “tape-on-reel” technology. These are developed 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. For automatic suction of the straight pin strips (180°) , a high-temperature-resistant “ pick-and-place pad” is arranged in the center of the pin strip. This "pick-and-place pad" included in the delivery package of the males headers in the "tape-on-reel" mode of delivery. The angled pin headers (90°) are designed in such a way that no “pick-and-place pad” is required for automatic suction.
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 .
Insulating material
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).
Contact surface
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.
Barely less essential in the SMT production process is reflow soldering: In this process step, an existing solder deposit is melted, whereby approx. 50% of the paste volume evaporates. 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.
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 soldering profiles for reflow soldering and wave soldering are included in the product catalog and in the data sheet of the individual 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.
Read more about the PCB and stencil design in the white paper Surface Mount Technology: integration of device connection technology in the SMT process
Wave soldered products in THT (Through Hole Technology), also known as pin-in-hole, is the best alternative to SMT (Surface Mount Technology) if higher forces can act on electromagnetic PCB components. The component design of Weidmüller products is specifically developed for this application and takes into account the requirements in terms of design types and processing from the beginning.
Wired (THT) PCB connectors and terminal blocks are processed using the wave soldering process. The pins of the component are pushed into the through-holes and are then run through one or more solder waves. When the solder is applied to the solder pins, the liquid solder is drawn into the through-hole due to the wetting and capillary forces and forms the solder joint.
Conventional through-hole technology (THT) is increasingly being replaced by surface mount technology (SMT). The reasons for this were both the constantly increasing requirements such as miniaturization of components, higher functional density and lower production costs as well as the major advances in the development of surface mount devices (SMD), which made the use of the SMT production process possible in the first place. SMT is now the accepted standard in PCB manufacture.
Discover our comprehensive SMT brochure and gain valuable insights into the latest developments, techniques and applications of surface mounting technology. Discover our comprehensive SMT brochure and gain valuable insights into the latest developments, techniques and applications of surface mounting technology. Download now for precise information and practical tips on implementing SMT in your production.
Whether you come to us as a device developer, product manager or buyer, we promise you efficiency, speed and tailored solutions. Weidmüller is your perfect partner for PCB connectors and PCB terminals. You can rely on our expertise and know-how. Working with you, we’ll find the products that meet your requirements.
