Design For Test
ICT provides fast, cost-effective, and highly accurate PCB testing, ensuring the detection of component-level faults for medium and high-volume production.
Design for Test (DFT)
Design for Test (DFT) is not just a design step – it is a mindset that ensures electronic assemblies can be tested efficiently and thoroughly using In-Circuit Test (ICT) systems.
At Forwessun, we know that the success of ICT testing depends on how well testability has been built into the design. Good DFT practices reduce fixture complexity, improve test coverage and ensure faults can be found quickly and accurately during PCB testing.
Why DFT Matters
In-Circuit Test remains one of the most effective ways to identify manufacturing defects such as solder faults, component failures or short circuits. However, ICT is only as strong as the access the design provides. Without adequate test pads and accessible nodes, test coverage is limited and fault isolation becomes harder.
By considering ICT during the design phase, engineers can ensure that test points are properly placed, spacing requirements are met and fixtures can be built without compromise. This early planning reduces reliance on functional testing alone, lowers fixture costs and delivers higher fault coverage – all of which shorten production cycles and improve yield.
Basic DFT requirements
| Fixture Type | Test Pad Size |
|---|---|
| Ideal test pad size | ≥0.024” |
| Smallest possible pad from bottom side | 0.018” |
| Smallest possible pad from top side | 0.020” |
Standard Probe:
| Probe Size Combination | Minimum Test Pad Spacing |
|---|---|
| 0.100” – 0.100” | 0.085” (2.16mm) |
| 0.100” – 0.075” | 0.075” (1.91mm) |
| 0.100” – 0.050” | 0.064” (1.63mm) |
| 0.075” – 0.075” | 0.068” (1.73mm) |
| 0.075” – 0.050” | 0.057” (1.45mm) |
| 0.050” – 0.050” | 0.048” (1.22mm) |
| 0.050” – 0.039” | 0.043” (1.09mm) |
| 0.039” – 0.039” | 0.039” (1.00mm) |
Probe to component spacing – based on 0.100” probes
Component height under 0.125” (3.175mm)
Minimum distance of Test pad centre to component edge – 0.039” (1.00mm)
Component height over 0.125” (3.175mm)
Minimum distance of Test pad centre to component edge – 0.050” (1.27mm)
Forwessun’s Approach to DFT and ICT
At Forwessun, we can work with customers to integrate ICT requirements directly into their PCB designs. Our team of engineers review layouts to confirm that all critical signals and nets are testable, and that access is optimised for ICT fixtures. Where needed, we advise on modifications that make ICT more efficient, such as repositioning components to allow easier probe access or adding additional pads to increase coverage.
These small design improvements can dramatically reduce fixture complexity, help with test software development time and improve the accuracy of fault diagnosis. The result is a faster, more reliable ICT process that supports high-volume manufacturing without introducing delays or hidden costs.
The Benefits of Design For Test
By applying DFT specifically for ICT testing, manufacturers gain measurable advantages. Test coverage is maximised, ensuring faults are detected at the earliest stage of production. Fixture design is simplified, which lowers cost and reduces the risk of mechanical stress on the PCB. Faults can be isolated more accurately, reducing rework time and ensuring products meet the highest quality standards before leaving the line, which makes our Full Turnkey Solutions the perfect choice, showing how we support you from initial design to end deployment.
In today’s electronics industry, where speed, reliability and cost control are critical, DFT for ICT provides a clear competitive advantage. It ensures ICT systems deliver their full potential, supporting both efficient production and long-term product reliability.
Smarter Testing with Forwessun
The relationship between design and testing is stronger than ever, and ICT is a prime example of why collaboration at the design stage is essential. At Forwessun, we make DFT for ICT a core part of our process, helping customers worldwide to reduce inefficiencies, improve coverage and achieve faster, more reliable production testing.
With our expertise in ICT systems, fixtures and applications, we ensure that testability is not an afterthought but an integral part of every design
