Assembly of printed circuit boards
The prototype assembly is done either manually or with the placement machine before the electrical components are fixed on the circuit boards, e.g. by means of vapor phase soldering.
Already during the production of small series, the complete assembly of the printed circuit boards is carried out by a modern SMD placement machine.
Prerequisite for the automatic assembly of printed circuit boards are special placement programs, which are obtained from the CAD data. Printed circuit boards with SMD components are processed at speeds > 10,000 components per hour. Typical for ergo: is the assembly of medium-sized series of approx. 100-1000 printed circuit boards with approx. 100-1000 components per board.
Details / steps of the assembly:
First, the printed circuit board data are either supplied by the customer or developed according to the customer's specifications complete with assembly plan via CAD by ergo: elektronik. The printed circuit boards are then produced by a printed circuit board manufacturer. Now the printed circuit board is placed in the cassette of the loader of the modular assembly line. After transport in the automatic screen printing machines of the assembly line, the printed circuit board is first printed with solder paste at the points of contact (pads) using a screen printing process. By means of optical inspection (photo comparison of the pads before and after printing with solder paste), the quality of the process is checked via the line’s own camera system (HawkEye, High Speed Deposit Verification System) before it continues with automatic placement in the second step in the inserter. With the technology used by ergo: elektronik, SMD (surface mount device) components are assembled by a four-head automatic placement machine: module 1 for smaller components up to 01005 such as capacitors, resistors and diodes and module 2 for larger components such as ICs, BGAs and connectors.
In the machine assembly of printed circuit boards the starting point for the placement is adjusted to the throughput time of the screen printer. In the third step, the assembled printed circuit board is fed into a vapor-phase soldering system. Here the assembled printed circuit board is heated to a temperature of 230°C in the vapor layer of the vapor phase soldering machine. Through a viewing window, one can see that wherever the grey solder paste was before visible at the edges of the assembled components, suddenly there is shining tin. ergo: uses both lead-free and leaded tin here - depending on the customer's requirements. In step four of assembly, the cooled printed circuit board is manually assembled with THD components (THD assembly), e.g. transformers, connectors, coils, relays, LEDs and large capacitors. In step five of the assembly, the printed circuit board with the manually assembled components is fed into a wave soldering machine where the THD components are soldered. At ergo: the soldering of complicated components with mixed assembly is carried out using a selective soldering system. In step six of the assembly, the optical inspection of all solder joints takes place before the electrical function tests of the fully assembled printed circuit board finally take place in step seven. The PCBs are assembled in compliance with the J-STD-001 standards. The assembled PCBs are approved in accordance with the IPC-A-610 standard.
The assembly of printed circuit boards with complex architectures requires both: a high degree of expertise and sophisticated equipment. Before 2007, ergo: elektronik assembled printed circuit boards externally. Today, the assembly of printed circuit boards is part of the core business of ergo: elektronik.