Mounting hole placement in PCB Design - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the mounting hole diameter.

PCB Design

mounting_hole_diameter = [1]  # in millimeters

Drag options to blanks, or click blank then click option'

A5.0

B3.2

C10

D0.5

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a hole diameter too small for screws.

Using a diameter that is not standard for mounting holes.

The standard mounting hole diameter is often 5.0 mm to fit common screws.

2fill in blank

medium

Complete the code to place a mounting hole at the top-left corner coordinates.

PCB Design

mounting_hole_position = ([1], 0)  # x, y in mm

Drag options to blanks, or click blank then click option'

A50

B10

C0

D-5

Attempts:

3 left

💡 Hint

Common Mistakes

Using a negative coordinate for the hole position.

Placing the hole too far from the edge.

The top-left corner x-coordinate is 0 mm, so the hole is placed at (0, 0).

3fill in blank

hard

Fix the error in the code to correctly calculate the center position of the mounting hole.

PCB Design

center_x = board_width [1] 2

Drag options to blanks, or click blank then click option'

A*

B/

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or multiplication instead of division.

Subtracting 2 instead of dividing by 2.

Dividing the board width by 2 gives the center x-coordinate.

4fill in blank

hard

Fill both blanks to create a dictionary of mounting hole positions with their labels.

PCB Design

mounting_holes = {"[1]": (0, 0), "[2]": (board_width, 0)}

Drag options to blanks, or click blank then click option'

Atop_left

Bbottom_right

Ctop_right

Dbottom_left

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up corner labels.

Using bottom corners instead of top corners.

The top-left hole is at (0,0) and the top-right hole is at (board_width, 0).

5fill in blank

hard

Fill all three blanks to calculate the distance between two mounting holes.

PCB Design

distance = ((x2 - [1])[2]2 + (y2 - [3])[2]2) ** 0.5

Drag options to blanks, or click blank then click option'

Ax1

B**

Cy1

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition instead of exponentiation for squaring.

Mixing up x and y coordinates.

This formula calculates the Euclidean distance between points (x1, y1) and (x2, y2).

Practice

1. What is the main purpose of mounting holes on a PCB?

easy

A. To cool down the PCB components

B. To securely fix the PCB inside a device

C. To provide electrical connections

D. To increase the PCB size

Solution

1. Step 1: Understand mounting hole function

   Mounting holes are designed to hold the PCB in place inside a device.

2. Step 2: Differentiate from other PCB features

   Electrical connections and cooling are done by traces and heat sinks, not mounting holes.

3. Final Answer:

   To securely fix the PCB inside a device -> Option B

4. Quick Check:

   Mounting holes = Secure fixing [OK]

Hint: Mounting holes hold the board physically [OK]

Common Mistakes:

• Confusing mounting holes with electrical vias
• Thinking holes cool components
• Assuming holes increase PCB size

2. Which of the following is the correct way to specify a mounting hole position on a PCB?

easy

A. Using x and y coordinates on the board

B. Using the hole diameter only

C. Using the color of the hole

D. Using the number of pins

Solution

1. Step 1: Identify position parameters

   Mounting holes are placed by specifying their x and y coordinates on the PCB layout.

2. Step 2: Exclude irrelevant options

   Hole diameter defines size, color and pin count are unrelated to position.

3. Final Answer:

   Using x and y coordinates on the board -> Option A

4. Quick Check:

   Position = x,y coordinates [OK]

Hint: Positions need x and y coordinates [OK]

Common Mistakes:

• Confusing hole size with position
• Using color or pins to locate holes
• Ignoring coordinate system

3. Given a PCB with mounting holes at coordinates (10, 20), (50, 20), (10, 60), and (50, 60), what is the distance between the two holes at (10, 20) and (50, 20)?

medium

A. 30 units

B. 60 units

C. 50 units

D. 40 units

Solution

1. Step 1: Identify coordinates of the two holes

   The holes are at (10, 20) and (50, 20), so they share the same y-coordinate.

2. Step 2: Calculate horizontal distance

   Distance = |50 - 10| = 40 units since y is the same.

3. Final Answer:

   40 units -> Option D

4. Quick Check:

   Distance = 50 - 10 = 40 [OK]

Hint: Subtract x values when y is equal [OK]

Common Mistakes:

• Calculating vertical distance instead
• Adding coordinates instead of subtracting
• Mixing x and y values

4. A PCB designer placed mounting holes at (15, 25), (15, 75), (65, 25), but forgot one hole to complete the rectangle. Which coordinate should be added to complete the mounting hole placement?

medium

A. (65, 75)

B. (15, 50)

C. (40, 75)

D. (65, 50)

Solution

1. Step 1: Identify existing hole coordinates

   Holes are at (15, 25), (15, 75), and (65, 25). Two share x=15, two share y=25.

2. Step 2: Find missing corner to form rectangle

   The missing corner must have x=65 and y=75 to complete the rectangle.

3. Final Answer:

   (65, 75) -> Option A

4. Quick Check:

   Opposite corner = (65, 75) [OK]

Hint: Complete rectangle with missing opposite corner [OK]

Common Mistakes:

• Choosing midpoint instead of corner
• Mixing x and y values incorrectly
• Ignoring rectangle shape

5. You need to place four mounting holes on a PCB sized 100x80 units. The holes must be 5 units from each edge. What are the correct coordinates for the holes?

hard

A. (5, 0), (95, 0), (5, 80), (95, 80)

B. (0, 0), (100, 0), (0, 80), (100, 80)

C. (5, 5), (95, 5), (5, 75), (95, 75)

D. (10, 10), (90, 10), (10, 70), (90, 70)

Solution

1. Step 1: Calculate hole positions from edges

   Each hole is 5 units from left/right edges (x=5 and x=100-5=95) and top/bottom edges (y=5 and y=80-5=75).

2. Step 2: List all four corner coordinates

   Holes are at (5,5), (95,5), (5,75), and (95,75).

3. Final Answer:

   (5, 5), (95, 5), (5, 75), (95, 75) -> Option C

4. Quick Check:

   Edges minus 5 units = hole coords [OK]

Hint: Subtract 5 from edges for hole positions [OK]

Common Mistakes:

• Using 0 or full edge coordinates
• Adding 10 units instead of 5
• Mixing x and y values