An electronic assembly (printed circuit board) is a very complex structure with many different components. It’s important to pay attention to the interactions between various mechanical, chemical and thermal processes. This applies not only to manufacturing, but also to component placement on the PCB. After all, in the development process the designer not only defines the function of the electronic assembly, but also largely determines the later production costs.
Error-free production data and production cost planning starting with the design phase have a major impact on product quality and product manufacturing costs. This is about design for manufacturing (DFM), also known as design for manufacturability.
The tolerances for the PCB manufacturer are a decisive aspect. PCBs are subject to unavoidable process tolerances due to the properties of the materials and the process operations (electroplating, photolithography, etching and pressing) as well as inaccuracies in the orientation of the drilling layout relative to the PCB layout or the track layout.
The tolerances define the differences between the allowable minimum and maximum sizes of drilled holes, track runs and track separations. These dimensions are subject to specific tolerances because they cannot be achieved any other way in production for cost reasons. As a rule, the smaller the tolerance specified by the designer, the higher the manufacturing cost.
Tips and tools
Eurocircuits offers information on tolerances and measures for uniform copper distribution on PCBs in design tips and videos available online at no charge. Guidelines for PCB designers describe proven methods for reducing PCB costs and minimizing errors during production. Software developed by Eurocircuits also gives designers suitable tools for detailed PCB checking before production.
These pre-production checks can reduce error rates from previous levels of up to 25% to less than 3%. Developers can also use a costing tool to determine PCB prices even before sending the data and select the optimal configuration.
That’s not all: Eurocircuits considers the next logical step after component placement on the PCB and includes downstream module production. An error in the design will lead to incorrect production data and delays in placement and assembly. The PCBA Visualizer or PCB Assembly Visualizer software identities all components and compares the component layout drawing to the design of the unpopulated PCB. This valuable tool for developers as well as module producers or electronic manufacturing service (EMS) providers checks whether the PCB design matches the bill of materials (BOM) and the component placement list (CPL).
Differences between these files are sometimes seen in practice, for example because components have been mirrored, moved or rotated. It is also possible that the wrong component has been selected and does not fit in the design layout. Another possibility is that the PCB designer views the PCB from below while the component drawing is a top view. This leads to mirroring of the two layouts and incompatibility in final assembly if the component footprint is asymmetrical.
This visualisation tool allows designers to work with a validated PCB design, a validated BOM, and validated CPL and 3D files for the assembled product. This dramatically reduces the number of errors before prototype manufacturing, which is especially advantageous when prototype PCBs and sample assemblies are needed very quickly.
This package service has met with a positive response: in 2019 Eurocircuits processed more than 4,250 placement and assembly orders and delivered finished prototypes. Hardware developers can place an order online and receive their fully assembled PCB within six days.
How ‘right first time’ works at Eurocircuits
Four-layer multilayer PCB manufacturing explained step by step
Tips, tricks and smart tools for PCB designers
Checking production data with PCBA Visualizer
All tutorial videos at Eurocircuits TV