PCB Blog - Matters needing attention in PCB board process

Here are a few factors that PCB board designers must consider and will influence their decisions:

1. Product functions

1) Basic functions of the basic requirements of the cage cover, including:

a. Interaction between schematic diagram and PCB layout

b. Wiring functions such as automatic fan-out wiring, push-pull and other wiring functions, as well as wiring capabilities based on design rule constraints

c. DRC validator

2) Ability to advance product features as the company engages in a more complex design

a. HdI (High density Interconnection) interface

b. Flexible design

c. Embed passive components

d. Radio frequency (RF) design

e. Automatic scripting is natural

f. Topology layout and cabling

g. Manufacturability (DFF), testability (DFT), producability (DFM), etc

3) Additional products can perform analog simulation, digital simulation, analog mixed signal simulation, high-speed signal simulation and RF simulation

4) Have a central component library that is easy to create and govern

2. A good partner who is technically in the leadership of the industry and has poured more effort than other manufacturers can help you design effective and technical products in a short time.

3. Price should be a secondary consideration among the above factors, and more attention should be paid to ROI.

PCB estimation needs to consider many factors. The types of development tools designers look for depend on the complexity of the design work they are doing. Because systems are becoming increasingly complex, the control of physical wiring and electrical component placement has evolved to such an extent that constraints must be set for hub paths in the design process. However, too many design constraints restrict the flexibility of design. Designers must have a good understanding of their designs and their rules so that they know when to use them. It shows a typical integrated system design from front end to back end. It begins with a design definition (schematic input) that is tightly integrated with constraint codification. In constraint codification, the designer can define both physical and electrical constraints. Electrical constraints will perform pre - and post - layout analysis for network validation drive emulators. Looking closely at the design definition, it is also linked to FPGA/PCB integration. The purpose of FPGA/PCB integration is to provide two-way integration, data governance, and the ability to perform co-design between FPGas and PCB. The same constraint rules for physical implementation are entered during the layout phase as during the design definition. This reduces the chance of making mistakes from file to layout. Pin switching, logic gate switching, and even input/output interface group (IO_Bank) switching all need to go back to the design definition stage for updates, so the design of each step is synchronized.

Let's look at some trends that are forcing designers to re-examine their existing development tool features and start ordering new ones:

1.HDI

Semiconductor complexity and the increase in the number of logic gates have required integrated circuits to have more pins and finer pin spacing. It is now common to design more than 2000 pins on a BGA device with 1mm pin spacing, let alone 296 pins on a device with 0.65mm pin spacing. Faster rise times and the need for signal integrity (SI) require more destination power supplies and ground pins, requiring more layers in the multilayer board, thus driving the need for high density interconnection (HDI) technology with microperforations. HDI is an interconnection technology being developed in response to these needs. The main characteristics of HDI technology are micro-hole and ultra-thin dielectric, finer wire and smaller line spacing.

2. The RF design

For RF designs, RF circuits should be designed directly into system schematics and system board layouts, rather than separate environments for subsequent conversions. All of the simulation, tuning, and optimization capabilities of RF emulation environments are still required, but emulation environments can accept more raw data than "real" designs. As a result, the differences between data models and the resulting design transformations will disappear. First, the designer can interact directly between the system design and RF simulation. Second, if designers are working on a large-scale or proportionally complex RF design, they may want to divide the circuit simulation task between multiple computing platforms running in parallel, or they may want to shorten the simulation time by sending each circuit in a multi-module design to its own emulator.

3. Improve the packaging of predecessors

The increasing functional complexity of modern products requires a corresponding increase in the number of passive devices, mainly in the number of decoupling capacitors and terminal matching resistors for low power and high frequency applications. Although packages of passive surface mount devices have shrunk considerably over the years, the results are still the same when trying to obtain the limiting density. Printed component technology enabled the transition from multi-chip components (MCM) and hybrid components to today's SiP and PCBS that are directly available as embedded passive components. The assembly techniques used in the transformation process. For example, the inclusion of an impedance material layer in a layered structure and the use of series terminal resistors directly under the microsphere grid array (uBGA) package have greatly improved the performance of the circuit. Embedded passive components can now be designed with high precision, eliminating the additional processing step of laser cleaning welds. Wireless components are also moving towards improving integration directly within the substrate.

4. Rigid flexible PCB

In order to design a rigid and flexible PCB, all factors affecting the assembly process must be considered. Designers cannot simply design a rigid flexible PCB as if the rigid flexible PCB were another rigid PCB. They must treat the bending areas of the design to ensure that the design points will not lead to conductor breakage and stripping due to stresses on the bending surface. There are still many mechanical factors to consider, such as bending radius, dielectric thickness and type, sheet metal weight, copper plating, overall circuit thickness, number of layers and number of bending sections. Understand rigid flexible design and decide if your product allows you to create a rigid flexible design.

5. Signal integrity planning

In recent years, new technologies related to parallel bus architectures and differential pair architectures for serial transformation or serial interconnection have been improved. The limitation of parallel bus design lies in the variation of system timing, such as clock skew and propagation delay. Design for timing constraints is still difficult because of clock skew across the entire bus width. Increasing the clock rate only makes the problem worse. On the other hand, differential pair architecture uses a exchangeable point-to-point connection to realize serial communication at the hardware level. Typically, it transfers data through a one-way serial "channel" that can be stacked in configurations of 1-, 2-, 4-, 8-, 16-, and 32- widths. Each channel carries one byte of data, so the bus can handle data widths from 8 bytes to 256 bytes, and data integrity can be maintained by using some form of error-detection technique. However, the high data rates lead to other design problems. Clock recovery at high frequencies becomes a burden for the system, as the clock quickly locks in the input data stream and minimizes all cycle to cycle jitter in order to improve the circuit's anti-jitter performance. Power noise also poses additional problems for designers. This type of noise increases the likelihood of severe jitter, which makes eye opening more difficult. Another challenge is to reduce common-mode noise and solve problems caused by lossy effects from IC packages, PCBS, cables and connectors.

6. Usability of design kits

Design kits such as USB, DDR/DDR2, PCI-X, PCI-Express and RocketIO will undoubtedly help designers move into new technologies. The design suite gives an overview of the technology, detailed instructions, and challenges designers will face, followed by simulations and how to create cabling constraints. It provides declarative documentation along with the program, which gives the designer a head start on new technologies that improve on older ones. It seems easy to get a PCB board tool that can handle layout; But it's important to get a tool that not only satisfies your needs but also addresses your immediate needs.