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What is DFM Check?

What is DFM Check?

Table of Contents

Design of Manufacturing (DFM) check is a common technique focusing on designing materials to provide economical manufacturing with higher efficiency. It involves different methods, such as designing processes and nominating different parts with equipment relocation, such that waste materials are reduced and output products are top-notch. Properly planned DFM ensures that manufacturing processes are sustainable, making more products to increase the sales of materials.

But before everything starts, I want to share the concept of DFX with you first, because it is complementary to the philosophy of our ELEPCB company. I hope it can give you a deeper understanding of DFM.

DFX and Design Process Reengineering

Design For eXcellence (DFX) is described in detail in the IPC-DFX standard. In a sense, X can represent the product life cycle or a certain part of it, such as assembly (M-making, T-testing), processing, use, maintenance, recycling, end-of-life, etc., and it can also represent the product competitiveness or factors determining the competitiveness of the product, such as quality (Q), cost (C), etc., including:

The 8 Elements of DFX
  • DFM: Design for Manufacture (DFM)
  • DFA: Design for Assembly (DFA)
  • DFT: Design for Test (DFT)
  • DFU: Design for Reuse
  • DFP: Design for Fabrication (DFF)
  • DFE: Design for Environment (DFE)
  • DFR: Design for Reliability (DFR)
  • DFC: Design for Cost (DFC)

Fg 1. 8 Elements of DFX

DFM belongs to a branch of DFX. With the development of the electronics industry, DFM occupies an increasingly important position in product design. Among the key factors affecting the cost of the product, it costs the least (only 5%), but The impact on products accounts for 70%. Therefore, we cannot take chances:

  • Problem XX is nothing, just control the production operation
  • Problem XX does not matter, customers will not notice“,  “…”.
Who casts the biggest shadow?

Fg 2. Who casts the biggest shadow?

A Description of DFM Development

The development of DFM has gone through several milestones such as the early stage of the THT plug-in era, the early stage of the introduction of SMT, and the mid-term development of SMT towards high density.

In the early stage of DFM, it was mainly characterized by plug-in devices. Due to the existence of molding equipment, manufacturing has almost no design requirements, and product developers are more flexible in design.

The DFM introduction period is when DFM design requirements are put on the agenda. The main feature is the early stage of surface mount, and the packaging is mainly surface mount devices with wing-shaped packages such as SOP and QFP. At this time, the use of printing machines, placement machines, and reflow soldering with a relatively high degree of automation constrains the design and development of products. Otherwise, the designed products will be difficult to mass produce. At this time, the DFM design rules are relatively simple.

As the integration level of products further increases, in the mid-term of DFM, its maturity has further improved. The main reason is the emergence of array devices represented by BGA, but this has brought about a series of problems.

What are the DFM Guidelines?

DFM guidelines are a set of rules and parameters that need to be followed to ensure the manufacturing process is as per industrial standard practice and optimized in production. The major guidelines for DFM are :

  • Limiting the cost of manufacturing

The DFM guidelines mainly focus on the quality of the outcome product, which is monitored and supported by the time taken to produce the product, the cost of manufacturing, and labor costs.

  • Modeling with standard tolerance

Not all designs are replicas, so some tolerance levels are set to ensure that the designs are symmetrical and meet the requirements of the output products. So, DFM plays a vital role in monitoring the model at a standard tolerance level. It addresses both human and machine-level errors as well as potential faults.

  • Optimized design

The process of DFM guidelines is followed by the design process, which needs to follow different guidelines and standards. The key performance parameters for the designs are to be followed such that the PCB designs are efficient, cost-effective, and take time to produce.

  • Nomination of reliable and accurate product

The PCB design process follows the manufacturing of the products, where the designed model comes to life. Ensuring different specifications of the designs meet different tools, materials of products, and processes need to align with each other to grow into a healthy product as per the designed materials.

Why is DFM Important?

DFM guarantees a high-efficiency manufacturing process to support the design process. Thus, DFM is crucial from the start to the end of the product design and manufacturing process, where it can save nearly 50% of the production process with optimized methods. It reduces the unnecessary costs that are lost in the timeline of manufacturing. It can act as a tool for benchmarking to evaluate the developed products against different manufacturing competitors.

The PCB design is a crucial step where many errors and issues arise, which can lower the outcome and damage entire hardware mounting configurations. Some of the common issues are the design of PCB layouts and irregular landing patterns, improper location of the components, poor soldering, component clearance, and haphazard selection of the components.

The statistics of DFM value in a company

Fg 3. The statistics of DFM value in a pcb company

When Should We Perform DFM Check?

PCB design for manufacturability should be performed in the early stages of circuit board design. It’s best to consider PCB manufacturability factors before starting schematic design and layout. By considering manufacturability during the design process, manufacturing issues and delays later on can be avoided. Here are some key moments when design for manufacturability should be performed:

  1. Schematic design stage: When drawing the schematic, the package type and pin layout of the individual circuit components should be taken into consideration to ensure that they comply with the standard packages available from the manufacturer. This helps avoid the need to modify the design later because the package is unavailable or unsuitable.
  2. Layout design stage: When doing PCB layout, the requirements and limitations of the manufacturing process should be taken into consideration. For example, ensure there is adequate spacing between components and good routing channels to allow for soldering and assembly during manufacturing. Also pay attention to the layout of ground and power planes to ensure good signal integrity and electromagnetic compatibility.
  3. Design Rule Check (DRC): After completing the layout, it is very important to perform a design rule check. By using the DRC function provided by PCB design tools, you can check whether the design complies with the manufacturer’s requirements and standards. This includes checking component spacing, minimum line width/space, pad size, etc.
  4. Communication with manufacturers: During the design process, maintaining close communication with manufacturers is key. They can provide advice on manufacturing processes, materials and techniques to ensure designs are achievable and meet quality standards.

In terms of DFM, the current status of the industry is that after engineers complete the design, they simply use CAM to preview the generated Gerber file, or send it directly to the PCB factory for board production without checking it at all. This leads to a large number of design risks flowing into the production end, ultimately leading to manufacturing difficulties.

Luckily, ELEPCB , as a long-established company provides PCB manufacturing & PCBA services, attaches great importance to DFM check and has a complete development and manufacturing team. As part of quality assurance, we are committed to outputting high-quality PCB products. Welcome to contact us at info@elepcb.com.

Steps to Perform a DFM Check

DFM checks are steps taken to ensure a PCB design is ready for trouble-free manufacturing. Here’s a simpler explanation:

DFM Tool

Fg 4. An image of DFM tool

Step 1: Review PCB Design Files

In preparing for your manufacturing process, it’s crucial to undertake a detailed review of the data sheets and drawings. This step will play a critical role in ensuring precision throughout production and preventing potential issues down the line. You need to conduct a thorough examination of the designs and the materials specified in the drawings. This examination aims to identify and implement changes to the PCB design, with the ultimate goal of achieving an economically efficient and effective design.

Step 2: Check Design Rule Compliance

After the design, different standards and safety factors need to be followed and should comply for the PCB design to be manufacturable and functional. Different design rules, such as trace widths, the distance between the pads, and the clearance of the components with each other. Also, the circuit design path needs to be considered for capacitive and inductive interference. Also, the design should be such that there are electrical operation factors.

Step 3: Inspect Component Placement

After finalizing the design, it’s important to pay close attention to how the parts are placed on the board. This step is crucial as it impacts factors such as heat dissipation, signal integrity, and ease of assembly. When positioning the components on the board, it’s advisable to allocate specific areas for powerful and critical parts. This strategic placement not only ensures the smooth functioning of the board but also simplifies the assembly process. By carefully considering component placement, you can optimize the performance and efficiency of your PCB.

Step 4: Analyze Signal Integrity

During the PCB manufacturing process, the PCB design undergoes various tests to assess its performance across multiple parameters. Tests are conducted to monitor factors such as harmonic interference, crosstalk, and impedance matching in the signals processed by the PCB. These tests are critical as they can impact the integrity of signal flow and control logic. By continuously monitoring these factors, any potential issues can be identified and addressed, ensuring the overall quality and reliability of the PCB design.

Step 5: Review Via Placement and Routing

Once the designs are reviewed, it’s important to consider how the parts are positioned and the wire connections are made. Care is taken to ensure that rearranging parts doesn’t complicate board assembly or disrupt signal integrity. Attention is also given to the layout of wires to ensure that electricity flows as intended without altering the primary function of the board. By paying close attention to these details, the overall functionality and ease of assembly of the PCB are optimized.

Step 6: Assess Mechanical Considerations

Following the design review, attention shifts to mechanical aspects such as board diameter, component hole mounting, and cutouts. These elements are carefully assessed to guarantee compatibility with the product enclosure and other mechanical components. Special consideration is given to verifying clearances for connectors and other components that interface with external devices.

By meticulously reviewing these mechanical aspects, manufacturers ensure seamless integration with the product enclosure and uphold the functionality and durability of the final product.

Step 7: Check for Manufacturing Constraints

In this step, you’ll review the PCB design for production, checking various factors such as the multi-layer PCB and tolerance levels of materials with complex component shapes. Additionally, you’ll verify the materials to ensure they meet standard requirements. The goal is to guarantee that the quality of manufacturing is not compromised and that the PCB module stays aligned with its intended goal.

Step 8: Perform Design Analysis and Simulation

After completing all the design and review processes, the PCB design undergoes various simulations. These simulations subject the design to different conditions and real-time environmental parameters to monitor its operational characteristics. Common analyses include thermal analysis, stress tests, power integrity simulations, and harmonics assessments.

Through simulation, you can identify the limits of the PCB and potential points of failure that may occur. This proactive approach enables us to refine the design and enhance its overall reliability before moving forward with production.

Step 9: Generate DFM Report

Once all reviews are completed, you will need to prepare a detailed breakdown report of the tests. These documents will primarily focus on the different tests and reviews conducted, highlighting any potential issues identified, and their probable impact on assembly and performance characteristics. Additionally, the report will present necessary recommendations along with correction factors. This comprehensive breakdown report is required to optimize the PCB design and ensure its overall quality and functionality.

Step 10: Iterate and Optimize Design

Use the report to make changes to the design to reduce issues, which might mean moving parts around, changing the design, or swapping out some parts.

Step 11: Final Review and Approval

Do one last review of everything. If all looks good and all issues are fixed, the design is ready to be made into a real board.

Typical Cases of DFM Checks

We can look at some typical DFM check cases. Common problems in DFM checks include but are not limited to the following two, which should be analyzed on a case-by-case basis.

Case 1: The analysis of the PCB layer

Figure 5 gives a case of PCB layer using DFM analysis, which can analyze the design rules of PCB such as soldermask design, pad design, pitch, silkscreen labeling, drilling design, and so on, so as to avoid undesirable consequences arising in the production process. Otherwise, these problems are difficult to find manually.

Case 1 - The analysis of the PCB layer

Fg 5. Case 1: The analysis of the PCB layer

Case 2: The analysis of power supply / ground layer

Figure 6 lists the analysis of the power supply/ground layer using the analysis tool, which can be used to analyze the anti pad design, thermal pad design, pad error deletion, to avoid low-level errors and failures, which is almost impossible to analyze manually.

Case 2 The analysis of power supply ground layer

Fg 6. Case 2: The analysis of power supply / ground layer

Difference Between DFM and DFA

DFM and DFA are two terms that are often confused, but they are very different things. I have provided a table here to aid in understanding:

Aspect
Design for Manufacturing (DFM)
Design for Assembly (DFA)
Objective
Optimize the product design for efficient manufacturing processes.
Simplify product assembly processes and reduce assembly time and costs.
Focus
Primarily focuses on the manufacturing stage of the product lifecycle.
Primarily focuses on the assembly stage of the product lifecycle.
Considerations
Material selection, process selection, tolerances, and manufacturing capabilities.
Component compatibility, part orientation, handling, and assembly sequence.
Goals
Reduce manufacturing complexity, minimize production costs, and improve quality.
Minimize assembly time, reduce parts count, enhance product reliability, and lower assembly costs.
Impact
It affects the design of individual components and the overall product structure.
Influences the arrangement and interaction of components during assembly.
Implementation
It typically involves collaboration between design engineers and manufacturing experts.
Requires input from both design engineers and assembly specialists to optimize product assembly.
Benefits
Streamlined manufacturing processes, reduced production lead times, and improved product consistency.
Faster assembly, lower labor costs, decreased risk of errors, and improved product maintainability.

DFM Check With ElEPCB

ElEPCB is one of the leading electronic PCB manufacturing and assembly companies that primarily focuses on designing PCBs, printing PCBs up to 24 layers, and quick scanning of the PCB designs to evaluate the design outcomes. At ElEPCB, we can automatically check the optical layer on the outside of the PCB module. This makes it easy to find odd connections, extra copper inside the PCB layouts, and issues with the quality of the soldered parts.

ELEPCB always insists on various PCB tests in quality control, and we also provide more corresponding articles, which can be viewed in our blog.

Conclusion

From the viewpoint of current development, DFM development has gone through the preliminary, early and middle stages, experienced software, digitalization, and is now gradually moving towards automation and intelligence. In the future, DFM, as the most dynamic component of product design, must be combined with artificial intelligence, expert systems and other technologies to support the comprehensive and parallel needs of modern product design. Follow the information exchange standards and adopt the results of information exchange standardization to realize the integration between the systems in the product design process.

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About Michael

Michael is the general manager of ELEPCB, a leading PCB design and manufacturing company based in China. He has over 10 years of experience in the PCB industry, and has been involved in various projects.

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