How to manage CTQ data

Managing Your CTQ Data During PCB Assembly

The highly-competitive electronics industry encompasses an ever-growing aspect of the GDP where product capabilities and functionality continually become smarter and services delivery relies more on algorithms and data processing. Therefore, it is essential for OEMs and others that develop and build PCBAs—the foundation of virtually all electronic systems—to meet or exceed customer quality standards. Otherwise, companies risk stagnant or declining market share. To stay competitive, you must emphasize quality control methods that define how your boards are manufactured. One means of accomplishing this is to effectively manage Critical to Quality (CTQ) data for the PCB assembly process.

What Is CTQ Data?

Before defining how CTQ data can be utilized for PCBA assembly, it is important to define CTQ, along with the CTQ Tree, a tool often used for implementation.


Critical to Quality (CTQ) refers to the attributes that your customers use to assess the quality of your products and services.

A CTQ Tree is a tool or method for transforming critical quality characteristics, as defined by your customers, into definable and quantifiable requirements and actions.

The CTQ Tree

A CTQ Tree provides a path from your customer’s defined quality expectations to a set or list of specific actions for satisfying those goals. As stipulated in the six sigma study guide, these should consist of three distinct levels.

Levels of a CTQ Tree

CTQ Tree levels

From the image above:

  • Customer Need - is a product or service characteristic that your customer has identified as critical to meet the level of quality they expect.
  • Quality Drivers - are the attributes that your customer uses to assess whether their need is met.
  • Performance Requirements - are the actions of your process that can be manipulated and measured that impact the quality drivers that define the customer need.

Creating Data from the CTQ Tree

The purpose of the CTQ Tree is to convert customer needs into measurable Critical to Client (CTC) activities. Examples of this technique for PCBA are shown below.


CTQ TREE Customer Need Quality Drivers Requirements
#1 High Reliability 1. High yield/low rework

2. Staking process execution

1. Defect and rework log

2. Staking material data

#2 Low Ionic Contamination 1. Baking/conformal coating

2. IPC TM-650 testing

1. Process data traceability

2. ROSE testing results

Instituting an effective CTQ tree requires that you understand the Voice of Client (VOC) and translate it into a usable customer need. There are several methods for accomplishing this objective. For example, you may apply a Kano model or the House of Quality to associate your CM’s PCBA process with your customers’ needs. The performance requirements are sometimes referred to as simply CTQs and can be defined by a quantity, action or other specific metric. This CTQ data can then be used to assess how well your PCB assembly service meets each customer’s quality bar.

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How to Utilize CTQ Tree Data to Improve PCB Assembly

As board assembly is performed by your CM, a few guidelines should be followed to make the best use of the CTQ data from your CTQ Tree.

Guidelines for Applying a CTQ Tree to PCB Assembly

  • Understand the PCB assembly process
    To determine what steps or procedures affect the quality drivers for your CTQ Tree, you must understand how your boards are assembled.
  • Ensure access to needed CTQ data
    Assessing the performance of your CTC implementation necessitates that you acquire meaningful data concerning any actions taken to meet the defined customer need. This will likely require data collection on the part of your CM; therefore, you should inquire about accessibility during the quoting process to avoid time loss with a manufacturer that does not support your QC efforts.
  • Collaborate with your CM
    It is essential that you work with your CM to identify actions that may be impactful and make changes necessary to help you meet your customer’s requirements. For example, if a specific circuit board testing method such as Ionic Chromatography is desired but not performed by the CM, ROSE testing may be employed as an alternative to provide the necessary CTQ data concerning board cleanliness.
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Competition for supplying PCBAs and electronics products can be fierce, and separating yourself from competitors may depend on how well you meet their expectations for quality. CTQ data can be very useful in satisfying customer demands; however, it requires collaboration with a CM that is committed to high-quality standards. Tempo Automation leads the industry for fast high-quality PCBA prototyping and low-volume manufacturing. And we will work with you throughout development to ensure your quality requirements are met.

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 using CTQ data from your PCB assembly, contact us.

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