THE INCREASING complexity and miniaturisation of electronic devices are the catalyst for the ongoing evolution of PCB design. But how are the suppliers of PCB design and prototyping tools coping with this evolution? Two Australian companies are well positioned to answer PCB design this question. SATCAM supplies software, hardware and consumables for the prototyping and manufacturing of PCBs and Altium is a global developer of solutions which aid engineers in designing and building next generation electronic products. electronic News spoke to both companies to hear their expert opinions.
1.Smaller, hotter According to SATCAM manager Rob Leslie, PCB designers are continuing to pack more components into ever smaller volumes, placing demand on smart design tools and accurate simulation. Leslie says this increased density usually equates to faster clock rates, resulting in higher currents that boost stray capacitances. While its possible to reduce operating voltages, this comes at a cost of a decreased signal-to-noise ratio (SNR). [In addition,] small devices and high powers means that the board designer has to think about heat flows as well as current flows, sometimes using exotic ceramic and/or aluminium-clad PCB materials, Leslie told Electronic News.
Altiums product marketing manager PCB design Rob Irwin agrees that miniaturisation and increasing density are driving PCB design trends, but adds that theres now a blurring of lines between the engineering process and the board layout and routing process. According to Irwin, components are benefiting from large scale integration, lowering the actual component count on the boards. At the same time, components are getting smaller, and increasing clock speeds generate more heat which means the chips demand special mounting requirements that must be addressed at the board level to ensure the devices function reliably. Many ICs these days have areas of the chip exposed in the package to allow for heat dissipation, Irwin explains. At the board level the designer needs to ensure that the necessary area of copper is exposed as part of the component footprint. Thermal issues are both an electrical problem, in terms of power consumption and losses, and also a mechanical problem, in terms of channelling heat away from hotspots, Irwin continues. To solve many of these problems designers need access to both design domains.
2.Information tsunami Irwins comment alludes to a major challenge for PCB designers; the amount of information needed on thousands of different component threatens to overwhelm even the most organised professional. Vendor websites, data sheets and reference designs on specific chips are valuable resources, but as the volume of data grows, Altium believes vendors will need to change their information delivery method to push component information and support directly into the design environment. The design system should be able to pull directly from the web all the necessary information and physical and software IP to implement the chip at the board level, the programmable device level and the software level, says Irwin. But PCB designers cant be experts in all fields. Altium claims the solution should be provided by the PCB design software, which needs to provide a high degree of automation of processes across design domains, allowing the creation of a unified data model of the entire electronic device.
3.Convergence According to Irwin, PCB designers are designing circuit components such as touch sensors directly onto the PCB in order to keep costs down. PCB design The challenge for board designers with this sort of technology is dealing with creating and scaling the complex shapes needed to implement the components, Irwin says. Perhaps not surprisingly, Irwin then points out that Altium Designer, for example, includes a library of parameterized touch sensor controls allowing a place and configure approach to the task. Irwin also says that Altium is seeing a convergence of board functionality into field-programmable gate arrays (FPGA), due to the affordability and increased functionality of those devices. Expiring patents on FPGA technology is also stimulating interest in PCB-FPGA co-design. A lot of designers are looking at FPGAs and comparing the cost of using them as system platforms versus the cost of a discrete 32-bit microcontroller and associated peripheral chips, Irwin eplains. The economics are shifting in favour of programmable devices.
However, FPGA design has traditionally been the realm of specialist designers, PCB design and FPGA vendor tools require the knowledge and skills associated with IC and ASIC design, increasing the steepness of the learning curve for board designers. Irwin says Altium is trying to help by driving for FPGA design to be unified with the board design process, so that designers can apply the system and circuit design skills they have acquired at the board level to the programmable hardware domain. Toward this end, the companys Designer software provides a high level component-based graphical approach to the creation of system functionality in the FPGA.
4.Prototyping Despite the advances made with PCB design and simulation software, SATCAMs Rob Leslie says Murphys Law means a physical prototype is still an important part of the development process. It is not unusual to find dimensional errors in component data sheets, and no amount of simulation will avoid those sorts of challenges, explains Leslie. Prototyping is as much about mechanical fit and potential manufacturability as it is about functionality and performance. Leslie is seeing a divergence in prototyping, with prototype multilayer boards with 0.2mm holes and 0.1mm tracks becoming less cost-effective. He says many designers are turning to modular prototyping to evaluate the performance of sections of a project.
There is also increasing demand for the ability to quickly produce an assembled, working prototype within a few hours of completing the PCB layout design. To cater for this, SATCAM has released the T-Tech Quick Circuit QCJ5 PCB design system, which has electronic a vacuum table and automated tool change feature for quick machining of thin and/or flexible circuits. Altium, on the other hand, argues that its software is a good alternative for checking for full fit and mechanical clearance. Altium Designer has a native 3D PCB design environment, so the board design itself is stored and worked on as a fully-editable 3D model. And designers can import 3D models of enclosures to check dimensions without a prototype or physical mock-up. Altium Designer also includes electronic a full set of CAM tools within the design environment, so users can process the board for typical manufacturing issues and eliminate these issues in the source files before going to manufacture. However, Altiums Rob Irwin agrees on the importance of physical prototypes, but advocates prototypes made on the contract manufacturers machines, electronic because even at a stage where the final board can be accurately modelled in detail, there still remains a data divide between design and manufacture.electronic Theres currently no guarantee that the data the manufacturer is using accurately reflects your design data in every detail, Irwin said, Design data is not used directly in the manufacture process.
The design data is massaged and reformatted to reflect the PCB design manufacturing equipment used. The lack of certainty regarding this translation process means prototypes are needed prior to committing to large production runs to check everything is acceptable. PCB design While a possible solution would be to directly connect CAD systems to manufacturing or prototyping systems, Irwin says manufacturers are resisting this, as preparing data for manufacture is a value-added service for them. Additionally, Irwin claims the problem of design and manufacture disconnect is not resolved by in-house initial prototyping, since the data will still need to be translated to work with the final contract manufacturers machinery.
5.Testing times Squeezed between the increasing demand for ever-smaller PCB design, more functional electronic devices and cost issues, todays PCB designers are facing challenges of an entirely different level to that of their predecessors. New convergences with FPGA and mechanical design, integration and scale complexity, thermal challenges and information management are some of the issues which PCB designers need to contend with. Fortunately, fast prototyping tools and advances in design software are on hand to keep up with these challenges PCB design.
