Print circuit board design A story about a handheld computer
Print circuit board design: When I was working in a handheld computer company, I made the mistake of using the SPECCTRA software tool to automate the routing of a 12-layer PCB (Figure 4); I thought SPECCTRA was super smart (and expensive) Human supervision or intervention is required to let it wind itself.
We made a jig to probe every signal on the PCI bus when the PCI bus was not working; they were all there and the timing was closed, but obviously not closed enough to work with the chip hanging off the bus. And that’s a bus with no connectors, only about 4 or 5 A in length…I don’t trust autorouters anymore without human supervision, ever!
Figure 4 This prototype 12-layer circuit board for the handheld looks great, but doesn’t work at all because the autorouter screwed up the PCI bus timing.
A story about consumer DVD players
When I was working at a semiconductor company, I was working on chips that drive laser heads in DVD recorders for PCs; I took a look at a client’s flex circuit prototype and knew they lacked experience in high-speed or thermal design , after all, the CD burners they made before had a lower data rate, and the chips they used didn’t generate too much heat. And we spent half a year teaching customers how to design their PCBs (Figure 5).
Figure 5 The laser driver soft circuit of DVD burner requires professional experience in PC motherboard or other high-speed, temperature-sensitive designs.
You can ask for help!
Don’t take your PCB design lightly, and pay close attention to the recommendations of component spec sheets; semiconductor manufacturers’ application engineers can help you a lot. But beware, semiconductor manufacturers’ application engineers are IC experts, not system engineers, so they might tell you today to separate the analog and digital ground planes and link them with an analog-to-digital converter (ADC) chip; but they Won’t tell you what to do if there are 5 ADCs on the board.
To learn more about Print circuit board design know-how, there are many training courses and technical seminars you can attend. Professional senior engineers will teach you how to properly use component layout and routing rules to make your design avoid noise or be sensitive to noise; you You can also learn to ensure your designs have good signal and power integrity.