PCB Blog - What factors should be look on PCB board evaluation process

For the PCB board technology article, the author can describe the challenges that PCB board design engineers have faced in recent times, as this has become an integral aspect of evaluating PCB board design. In the article, how to meet these challenges and potential solutions can be discussed; when solving PCB board design evaluation problems, the author can use Mentor's PCB board evaluation software package as an example. As a research and development personnel, the consideration is how to integrate the advanced technology into the product. These advanced technologies can be reflected not only in excellent product functions but also in reducing product costs. The difficulty lies in how to effectively apply these technologies to products. There are many factors to consider, and time-to-market is one of the most important factors, and many decisions around time-to-market are constantly being updated. There is a wide range of factors to consider, ranging from product functionality, design implementation, product testing, and electromagnetic interference (EMI) compliance. It is possible to reduce design iterations, but it depends on the completion of the previous work. Most of the time, the easier it is to find problems later in the product design, and the more painful it is to make changes to the problems found. Here are a few factors that PCB board designers must consider and influence their decision:

1. Product function

1.1 Essential functions covering essential requirements, including:

1) Interaction between schematic and PCB board layout

2) Routing functions such as automatic fan-out routing, push-pull, and routing capabilities based on design rule constraints

3) DRC checker

1.2 The ability to upgrade product functionality as the company engages in a more complex design

1) HDI (High-Density Interconnect) interface

2) Flexible design

3) Embed passive components

4) Radio Frequency (RF) Design

5) Automatic script generation

6) Topological layout and routing

7) Manufacturability (DFF), Testability (DFT), Manufacturability (DFM), etc.

2. A good partner who is technically in the industry leader and has devoted more effort than other manufacturers, can help you design products with efficacy and technology in a short period of time

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

There are many factors to consider in PCB board evaluation. The type of development tools a designer is looking for depends on the complexity of the design work they are doing. As systems tend to become more complex, control of physical routing and placement of electrical components has grown so extensive that constraints must be placed on critical paths in the design process. However, too many design constraints limit the flexibility of the design. Designers must have a good understanding of their designs and their rules, so they know when to use those rules. The same constraint rules for physical implementation are entered during the layout phase as during the design definition. This reduces the chance of errors going from file to layout. Pin exchange, logic gate exchange, and even input and output interface group (IO_Bank) exchange all need to return to the design definition stage for updating, so the design of each link is synchronized. A trend of designers revisiting their existing dev tools capabilities and starting to order some new ones:

3.1 HDI

The increase in semiconductor complexity and the total number of logic gates has required integrated circuits with more pins and finer pin pitches. It is common to design more than 2000 pins on a BGA device with 1mm pitch, let alone 296 pins on a device with 0.65mm pitch. Faster rise times and Signal Integrity (SI) requirements require a higher number of power and ground pins, which require more layers in a multilayer board, thereby driving a high demand for microvias. The need for density interconnect (HDI) technology. HDI is an interconnect technology that is being developed in response to the above needs. Micro vias and ultra-thin dielectrics, thinner traces, and smaller line spacing are key features of HDI technology.

3.2 RF Design

For RF design, RF circuits should be designed directly into the system schematic and system board layout, rather than a separate environment for subsequent conversions. All of the simulation, tuning, and optimization capabilities that the RF simulation environment provides are still required, but the simulation environment accepts more raw data than the "real" design. As a result, the differences between the data models and the resulting problems of design transitions will disappear. First, designers can interact directly between system design and RF simulation; second, if designers are working on a large-scale or fairly complex RF design, they may want to distribute circuit simulation tasks to multiple computing platforms running in parallel, or They wanted to reduce simulation time by sending each circuit in a design consisting of multiple blocks to its own simulator.

3.3 Advanced Packaging

The increasing functional complexity of modern products requires a corresponding increase in the number of passive components, mainly reflected in the increase in the number of decoupling capacitors and termination resistors in low-power, high-frequency applications. While the packaging of passive surface mount devices has shrunk considerably over the years, the results remain the same when trying to achieve the ultimate density. Printed component technology has enabled the transition from multi-chip modules (MCMs) and hybrid components to today's SiP and PCB boards that are directly available as embedded passive components. The assembly technology is used in the transformation process. For example, the inclusion of a layer of resistive material in a layered structure and the use of series termination resistors directly under the micro ball grid array (BGA) package have greatly improved circuit performance. Embedded passive components can now be designed with high precision, eliminating the need for additional processing steps for laser-cleaned welds. There is also a movement towards increased integration directly within the substrate in wireless components.

3.4 Rigid-flex PCB

In order to design a rigid-flex PCB board, all factors that affect the assembly process must be considered. Designers cannot design a rigid-flex PCB as simple as designing a rigid PCB, as if the rigid-flex PCB were just another rigid PCB. They must manage the flex area of the design to ensure that the design points will not lead to breakage and stripping of conductors due to stress on the flex surfaces. There are still many mechanical factors to consider, such as bend radius, dielectric thickness and type, sheet metal weight, copper plating, overall circuit thickness, number of layers, and number of bends. Understand the rigid-flex design and decide if your product allows you to create a rigid-flex design.

3.5 Signal Integrity Planning

In recent years, new technologies related to parallel bus structures and differential pair structures for serial-to-parallel conversion or serial interconnection have been continuously advanced. On the other hand, the differential pair structure uses an exchangeable point-to-point connection at the hardware level for serial communication. Typically, it transfers data over a unidirectional serial "lane" that can be stacked in 1-, 2-, 4-, 8-, 16-, and 32-width configurations. Each channel carries one byte of data, so the bus can handle data widths from 8 to 256 bytes, and data integrity can be maintained through the use of some form of the error detection technique. However, other design issues arise due to the high data rates. Clock recovery at high frequencies becomes a burden on the system, as the clock needs to quickly lock to the incoming data stream and reduce all cycle-to-cycle jitter in order to improve the circuit's anti-jitter performance. Power supply noise also creates additional problems for designers. This type of noise increases the potential for severe jitter, which makes eye-opening more difficult. Another challenge is to reduce common-mode noise and address issues caused by loss effects from IC packages, PCB boards, cables, and connectors.

3.6 Utility of Design Kits

Design kits such as USB, DDR/DDR2, PCI-X, PCI-Express and RocketIO will undoubtedly be of great help to designers entering new technologies. The Design Kit gives an overview of the technology, detailed descriptions, and difficulties that designers will face, followed by simulation and how to create routing constraints. It provides descriptive documentation along with the program, which provides designers with an opportunity to master advanced new technologies. It may seem easy to get a PCB board tool that can handle layout, but getting a tool that not only satisfies layout but also solves your pressing needs is critical.