Test point placement in PCB Design - Dashboard Guide

Dashboard Mode - Test point placement

Goal

Understand how test points are placed on a PCB to ensure easy access for testing and debugging.

Sample Data: PCB Test Points

Test Point ID	Net Name	X Position (mm)	Y Position (mm)	Accessible (Yes/No)	Signal Type
TP1	VCC	10	5	Yes	Power
TP2	GND	12	5	Yes	Ground
TP3	DATA1	15	8	No	Signal
TP4	CLK	18	7	Yes	Signal
TP5	RESET	20	6	No	Signal
TP6	VCC	22	5	Yes	Power

Dashboard Components

• KPI Card: Total Test Points - Formula: Count of Test Point IDs = 6
• KPI Card: Accessible Test Points - Formula: Count where Accessible = 'Yes' = 4
• Bar Chart: Test Points by Signal Type - Counts grouped by Power, Ground, Signal
• Table: List of Test Points with positions and accessibility
• Scatter Plot: Test Point Positions (X vs Y) - Points colored by Accessibility (Yes=green, No=red)

Dashboard Layout

+----------------------+----------------------+
| Total Test Points (6) | Accessible Points (4) |
+----------------------+----------------------+
|                      Bar Chart: Test Points by Signal Type           |
+---------------------------------------------------------------------+
| Table: Test Points List               | Scatter Plot: Positions     |
| (with accessibility and positions)  | (X vs Y colored by access)  |
+---------------------------------------------------------------------+

Interactivity

Filter by Signal Type (Power, Ground, Signal) updates the Bar Chart, Table, and Scatter Plot to show only selected types. Selecting a Test Point in the Table highlights it on the Scatter Plot.

Self Check

If you add a filter to show only Accessible = 'Yes', which components update and what changes occur?

• Bar Chart updates to count only accessible test points by signal type.
• Table shows only accessible test points.
• Scatter Plot shows only accessible points (green dots).
• KPI cards update: Total Test Points remains 6, Accessible Test Points remains 4.

Key Result

Dashboard shows PCB test points count, accessibility, signal type distribution, and spatial positions for test point placement analysis.

Practice

1. What is the main purpose of placing test points on a PCB?

easy

A. To increase the size of the PCB

B. To make circuit testing easier and faster

C. To add decorative elements to the board

D. To reduce the number of components

Solution

1. Step 1: Understand the role of test points

   Test points are used to access signals and power lines easily during testing.

2. Step 2: Identify the main benefit

   They help make testing faster and easier by providing convenient access.

3. Final Answer:

   To make circuit testing easier and faster -> Option B

4. Quick Check:

   Test points purpose = easier testing [OK]

Hint: Test points simplify testing by providing easy access [OK]

Common Mistakes:

• Thinking test points are for decoration
• Assuming test points reduce PCB size
• Confusing test points with components

2. Which of the following is the correct way to label a test point on a PCB?

easy

A. Use a clear, unique identifier near the test point

B. Leave it unlabeled to save space

C. Label it with random numbers

D. Use the same label for multiple test points

Solution

1. Step 1: Recognize labeling best practices

   Labels should be clear and unique to avoid confusion during testing.

2. Step 2: Evaluate options

   Clear and unique identifiers near the test point follow best practices; other approaches lead to confusion or errors.

3. Final Answer:

   Use a clear, unique identifier near the test point -> Option A

4. Quick Check:

   Labeling = clear and unique [OK]

Hint: Always label test points clearly and uniquely [OK]

Common Mistakes:

• Leaving test points unlabeled
• Using duplicate labels
• Using random or unclear labels

3. Given a PCB with test points placed too close together, what is the likely outcome during testing?

medium

A. No impact on testing quality

B. Testing will be faster and easier

C. Signals may short or cause confusion

D. Test points will automatically adjust spacing

Solution

1. Step 1: Analyze spacing impact on test points

   Test points placed too close can cause signal shorts or confusion during probing.

2. Step 2: Assess testing consequences

   This can lead to inaccurate test results or damage to the circuit.

3. Final Answer:

   Signals may short or cause confusion -> Option C

4. Quick Check:

   Close spacing = shorts/confusion [OK]

Hint: Keep test points spaced to avoid shorts [OK]

Common Mistakes:

• Assuming test points auto-adjust spacing
• Ignoring impact of close spacing
• Believing close spacing improves testing

4. A PCB designer placed test points on all signals but forgot to label them. What is the main problem this causes?

medium

A. The PCB will fail manufacturing

B. Test points will not function electrically

C. Test points will cause signal interference

D. Test points cannot be identified quickly during testing

Solution

1. Step 1: Understand the role of labeling

   Labels help testers quickly identify which test point corresponds to which signal.

2. Step 2: Identify the consequence of missing labels

   Without labels, testers waste time or make errors locating signals.

3. Final Answer:

   Test points cannot be identified quickly during testing -> Option D

4. Quick Check:

   Missing labels = slow identification [OK]

Hint: Label test points to avoid confusion during testing [OK]

Common Mistakes:

• Thinking unlabeled points fail electrically
• Assuming unlabeled points cause interference
• Believing unlabeled points stop manufacturing

5. You need to place test points on a PCB with limited space. Which strategy best ensures effective testing without causing shorts or confusion?

hard

A. Place test points on key signals with clear labels and maintain minimum spacing

B. Place test points randomly to save space and label later

C. Place test points only on power lines without labels

D. Cluster all test points tightly and use one label for the group

Solution

1. Step 1: Identify key signals for test points

   Focus on important signals and power lines to maximize testing value.

2. Step 2: Ensure clear labeling and spacing

   Labels help quick identification; spacing prevents shorts and confusion.

3. Step 3: Avoid random or clustered placement

   Random or clustered points cause errors and make testing difficult.

4. Final Answer:

   Place test points on key signals with clear labels and maintain minimum spacing -> Option A

5. Quick Check:

   Key signals + labels + spacing = effective testing [OK]

Hint: Prioritize key signals, label clearly, keep spacing [OK]

Common Mistakes:

• Placing points randomly without labels
• Ignoring spacing causing shorts
• Using one label for multiple points