Features of CTQ processes

Organizing Your CTQ Dimensions for PCBA Manufacturing

Quality is one of those often used words that can be elusive to define. For example, what specific characteristics does a person of good quality possess? In this case, the most accurate definition of quality likely belongs to the person making the assessment. But how can you ensure that you meet a quality standard that can change with each assessor? That is where CTQ comes in.

CTQ is a six-sigma technique for identifying and satisfying what a customer defines as a quality attribute of the product or service that is provided to them. CTQ data provide the measurable results for process requirements defined for evaluating whether expectations are met. Assessing whether a CM’s PCBA manufacturing process contributes to the satisfaction of their customers’ quality demands requires meaningful CTQ dimensions for each stage, procedure and step, along with an understanding of PCBA manufacturing quality drivers.

Understanding the PCBA Manufacturing Quality Drivers

One of the more challenging aspects when implementing a CTQ strategy is aligning customer-defined quality issues or concerns with actual PCBA manufacturing procedures that can be modified and monitored. To accomplish this, you must understand customer quality drivers and the design choices that influence the quality of the board build process.

Design Choices That Drive PCBA Manufacturing Quality 

  • Fabrication
  1. Material selection
  2. Layer count
  3. Need for sequential lamination
  4. Copper trace specifications
  5. Dimension specificity
  • Assembly
  1. Board type
  2. Component technology
  3. Unique component count
  4. Additional and/or non-standard assembly requirements

The design decisions listed above establish boundaries for your CM’s process. Therefore, you should utilize your CM’s DFM rules and guidelines to ensure the manufacturability of your boards. To ensure that your CTQ methodology will be effective, these drivers must translate into specific manufacturing actions or steps measurable by accurate CTQ dimensions.

CTQ Dimensions for Your Board Build Process

The measurability of process results represents an essential part of the CTQ strategy application process. Not only do the results need to be measurable, but they should also be meaningful in relation to both the PCBA manufacturing process and customer demand. This necessitates the selection of proper drivers for assessment and accurate CTQ dimensions. The table below outlines how to match CTQ dimensions with customer demand for two cases: 1.) Customer demand for on-time delivery; 2.) A zero failure rate.


                         Customer Demand

Quality Drivers

CTQ Dimensions

PCBA fits within a defined enclosure

Component package type

Maximum z-dimension of assembled board

No and width of layers

PCBA meets cleanliness requirements for its environment throughout projected lifecycle

Moisture level

Ionic contamination level

Conformal coating type

DFM for HDI Printed Circuit Boards

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Case 1: 

Your customer has defined on-time delivery for all orders as the quality standard they expect. As you develop new custom products for this customer, the prototyping stage can be unpredictable. However, you know that prototyping typically requires 3 to 7 design⇒build⇒test (DBT) iterations to achieve a production-ready design. Therefore, the quality drivers for this case include the speed of iteration and the number of iterations. If we set the optimal CTQ value at 15 days for a particular design, then a reasonable CTQ dimension for process evaluation is the number of days required for a complete iteration. For example, if a production-ready design takes five iterations and one iteration takes three days, the optimal CTQ value has been reached. However, if the average iteration takes four days, the customer’s expectations are not being met.

Case 2:

The customer requests that all boards last through their operational lifecycle. This may seem like a big ask, but some drivers can increase or decrease the probability of fulfilling this goal. For example, the IPC classification requested dictates the types and number of acceptable manufacturing defects. The higher the classification, the harder it is to meet. Additionally, the more specific dimensions you assign for your design, the less flexibility your CM has for making adjustments to facilitate board construction and reliability. It is a good idea to specify essential values only and let your CM do the rest. In this case, a useful CTQ dimension is the yield rate per classification level. That is how the yield rate, or the number of usable boards to boards made, varies according to requirements for the different classifications.

Tempo's Custom PCB Manufacturing Service
  • ISO-9001, IPC-600, and IPC-610 commitment to quality certifications.
  • Execute your full development cycle from proto to validation, NPI, and low volume production.
  • Accurate quote in less than a day.
  • Performs entire turnkey process in as fast as 4 days.
  • DFX support, including DFM, DFA, and DFT from Day 1 of design.
  • Sources components from the most reputable suppliers in the industry. to reduce procurement time.
  • Software-driven smart factory with monitoring and control throughout the manufacturing process.
  • Performs multiple automated inspections during PCB assembly to ensure PCB quality for prototyping.
  • Smooth transition from prototyping to production.

Deploying a CTQ strategy is a good way to ensure that you are not only listening to your customers but taking tangible steps to meet their quality expectations. Be sure to work with a CM that employs a transparent process that promotes tracking and data acquisition. At Tempo Automation, the industry leader for fast, accurate, high-quality PCBA prototyping and low-volume production, we utilize a software-based digital thread manufacturing to ensure that your boards meet your quality standards. And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.

If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on how to utilize CTQ dimensions effectively for use in satisfying your customer quality demands, contact us.

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