I. Assembly process
SMT assembly takes place on one of the most modern assembly lines in Europe. Our company uses Panasonic machines, which provide the highest level of quality while maintaining very high efficiency.
Before production starts, in parallel to ordering electronic components, it is necessary to order a stencil for a solder paste printer. Due to the required high precision of printing, the stencils are made from sheets of stainless steel with a laser cut and thickness matched to the product. In some cases, electropolishing is applied, which allows to add additional properties during the paste printing operation.
The stencils prepared this way are adjusted to the standard of the VectorGuard system which is used in the company. For the production of each stencil, it is crucial to prepare technical data, such as calculating the volume of paste applied through the stencil, defining the shape of the paste after printing, possible use of aperture reduction or the so-called “Overprint”.
- The first stage of assembly is solder paste printing carried out by a Panasonic SPG stencil printer (screen printer). Its task is to precisely apply the solder paste to the printed circuit board through a specially prepared template dedicated to the product. The accuracy of the print determines whether the final product from the SMT line will be properly manufactured and will not have defects such as short circuits between component terminals, etc.
- The printed circuit board with the applied paste is transported automatically to the SPI machine called “Solder paste inspection”, made by PARMI SIGMA-X, where they are subjected to an automatic inspection process using precise lasers. The inspection takes a few seconds, when the machine checks the accuracy and correctness of applying the solder paste to the PCB, which, after verification, is transferred to the assembly of components.
- The assembly of SMD components, both passive and active, takes place in Panasonic NPM-D2. NPM-D2 machines offer very high efficiency while using very advanced methods of controlling SMD components before mounting on a PCB. During the assembly of passive components, parameters such as length, width and height of the component are measured, and for components with leads in the form of pins or balls, the number of leads, their size, possible dimensional deviations, etc. are additionally checked. To verify these parameters, 2D and 3D cameras are used, which perform a split-second inspection for all components carried by the assembly head.
- Panasonic NPM-D2 machines have a modern modular structure, which allows for increased efficiency by adding additional modules to the production line.
- Special Panasonic DGS software is dedicated to operate the production line, in which programs are prepared in accordance with the BOM (Bill of material; material structure of the product), component parameters are defined, and information about the efficiency and quality of the process is collected.
- After assembling the whole package, it goes to the visual inspection station, where a trained operator checks the correctness of the surface assembly.
- The next step is soldering in a reflow oven. The reflow oven is designed to heat the packet to the soldering temperature and then cool it down to the ambient temperature. In order for the solder joints to have the appropriate properties and be free from defects, it is necessary to precisely set the temperature curve (profile) and rigorous monitoring of these parameters. The heating profile is obtained by comparing the process parameters recommended by the paste supplier with the parameters resulting from the package characteristics (type of SMD components used) and the required operating cycle. Prepared in this way, the initial profile is tested with the use of electronic components and a special control and measurement device – ECD SUPER MOLE 2. In the case of various electronics packages, setting the appropriate profile requires a lot of knowledge and experience of the engineer. The solder quality is checked under a microscope and in an X-ray inspection machine.
- The next stage of production is the “Automatic optical inspection” AOI machine. The panels are subjected to automated control using a laser through the highly efficient AOI PARMI Xceed machine. The machine checks the correctness of soldering and the quality of the solder joints, and also dimensions, part numbers, position etc. of components are checked. Machine is also capable of mechanical damage of the PCB surface verification.
- For the product manufactured with the use of BGA (Ball Grid Array) memory components, additional control in the process is required in order to check the correctness of connections. BGA components have terminals under the circuit, which are invisible to the naked eye after the soldering process, therefore the use of an X-ray machine takes place. The machine used in WESA generates radiation with the use of appropriate equipment powered by electricity, thanks to which full control over the duration and power of radiation is ensured. Based on the obtained photos, the trained staff is able to determine where in the SMT line any problems have occurred and how to prevent them.