Ordering PCBs from fabricators in PCB Design - Cell-by-Cell Formula Trace

Sample Data

This table shows three PCB fabricators with their unit cost per PCB and the quantity of PCBs ordered. The goal is to calculate the total cost for each fabricator.

Cell	Value
A1	Fabricator
B1	Unit Cost
C1	Quantity
D1	Total Cost
A2	FabA
B2	5.00
C2	100
D2
A3	FabB
B3	4.50
C3	150
D3
A4	FabC
B4	5.20
C4	120
D4

Formula Trace

=B2*C2

Step 1: B2

Step 2: C2

Step 3: 5.00 * 100

Cell Reference Map

    A       B       C       D
1 |Fabricator|Unit Cost|Quantity|Total Cost
2 |  FabA   |  5.00  |  100   |  =B2*C2 
3 |  FabB   |  4.50  |  150   |  =B3*C3 
4 |  FabC   |  5.20  |  120   |  =B4*C4 

The formula references the unit cost in column B and quantity in column C for each fabricator row to calculate total cost in column D.

Result

    A       B       C       D
1 |Fabricator|Unit Cost|Quantity|Total Cost
2 |  FabA   |  5.00  |  100   |  500.00 
3 |  FabB   |  4.50  |  150   |  675.00 
4 |  FabC   |  5.20  |  120   |  624.00 

The total cost column shows the result of multiplying unit cost by quantity for each fabricator, giving the total price to order PCBs.

Sheet Trace Quiz - 3 Questions

What does the formula =B2*C2 calculate?

A Unit cost per PCB

B Total cost for FabA

C Quantity of PCBs

D Sum of unit cost and quantity

Key Result

Multiply unit cost cell by quantity cell to get total cost for each fabricator row.

Practice

1. What is the primary purpose of ordering PCBs from fabricators?

easy

A. To simulate electronic circuits on a computer

B. To turn your design into a physical board for testing or production

C. To create 3D models of the PCB

D. To write software code for the PCB

Solution

1. Step 1: Understand the role of PCB fabrication

   PCB fabrication is the process of making a physical printed circuit board from a design.

2. Step 2: Identify the purpose of ordering PCBs

   Ordering PCBs from fabricators allows you to get a real board for testing or production use.

3. Final Answer:

   To turn your design into a physical board for testing or production -> Option B

4. Quick Check:

   PCB ordering = physical board creation [OK]

Hint: PCB fabrication means making a real board from your design [OK]

Common Mistakes:

• Confusing PCB fabrication with software coding
• Thinking PCB ordering creates simulations
• Assuming it produces 3D models instead of physical boards

2. Which of the following file types is essential to provide when ordering PCBs from fabricators?

easy

A. JPEG images

B. Word documents

C. Gerber files

D. MP3 audio files

Solution

1. Step 1: Identify the standard file format for PCB fabrication

   Gerber files contain the detailed layer information needed by fabricators to produce PCBs.

2. Step 2: Compare with other file types

   JPEG, Word, and MP3 files do not contain PCB manufacturing data and are irrelevant for fabrication.

3. Final Answer:

   Gerber files -> Option C

4. Quick Check:

   Gerber files = PCB manufacturing data [OK]

Hint: Gerber files are the PCB blueprint for fabricators [OK]

Common Mistakes:

• Submitting image files instead of Gerber files
• Confusing documentation files with fabrication files
• Not knowing the correct file format for PCB production

3. You have two fabricators: Fabricator A charges $50 for 10 PCBs with 7 days delivery, Fabricator B charges $40 for 10 PCBs with 14 days delivery. If you need the PCBs urgently, which fabricator should you choose?

medium

A. Fabricator A because of faster delivery

B. Fabricator B because it is cheaper

C. Either one, delivery time does not matter

D. Order from both to compare quality

Solution

1. Step 1: Analyze delivery times

   Fabricator A delivers in 7 days, Fabricator B in 14 days.

2. Step 2: Consider urgency

   If PCBs are needed urgently, faster delivery is more important than cost.

3. Final Answer:

   Fabricator A because of faster delivery -> Option A

4. Quick Check:

   Urgent need = choose faster delivery [OK]

Hint: Urgent orders need faster delivery, not just cheaper price [OK]

Common Mistakes:

• Choosing cheaper option despite urgent need
• Ignoring delivery time importance
• Thinking ordering both is always best

4. You submitted Gerber files to a fabricator but received an error saying files are incomplete. What is the most likely cause?

medium

A. Missing one or more required Gerber layers

B. Files are too large in size

C. You sent JPEG images instead of Gerber files

D. The fabricator does not accept Gerber files

Solution

1. Step 1: Understand Gerber file requirements

   Fabricators require all necessary layers (copper, solder mask, silkscreen, etc.) to produce PCBs.

2. Step 2: Identify common error cause

   An incomplete set of Gerber layers causes errors during file validation.

3. Final Answer:

   Missing one or more required Gerber layers -> Option A

4. Quick Check:

   Incomplete Gerber layers = error [OK]

Hint: Check all required Gerber layers are included before submitting [OK]

Common Mistakes:

• Assuming file size causes error
• Sending wrong file types
• Thinking fabricators reject Gerber files

5. You want to order 50 PCBs with the following specs: 2-layer board, 1.6mm thickness, HASL finish, and 0.8mm minimum trace width. Which step should you take to ensure the fabricator can meet these requirements?

hard

A. Ask the fabricator to decide the specs after receiving the files

B. Send only the Gerber files without any specification details

C. Order the PCBs without confirming specifications to save time

D. Check the fabricator's specification sheet for supported thickness, layers, finish, and trace width

Solution

1. Step 1: Understand importance of specification matching

   Fabricators have limits on board thickness, layers, finishes, and trace widths they can produce.

2. Step 2: Verify fabricator capabilities

   Reviewing the fabricator's specification sheet ensures your requirements are supported before ordering.

3. Final Answer:

   Check the fabricator's specification sheet for supported thickness, layers, finish, and trace width -> Option D

4. Quick Check:

   Confirm specs with fabricator before ordering [OK]

Hint: Always verify fabricator specs match your PCB requirements [OK]

Common Mistakes:

• Assuming fabricator can produce any specs
• Not communicating specs clearly
• Relying on fabricator to guess requirements