---
title: "Factors in component placement"
subject: "Instrumentation II"
chapter: 8
key: "semester_5/instrumentation_ii:component-placement"
source: https://www.bctengineer.com/q/semester_5/instrumentation_ii/component-placement
site: BCT Engineering
---

# Factors in component placement

Instrumentation II · Chapter 8: Circuit Layout

- Asked in: 2073 Shrawan, 3 marks; 2070 Chaitra, 3 marks (asked 2 times)
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/instrumentation_ii/component-placement
- Whole chapter: https://www.bctengineer.com/md/semester_5/instrumentation_ii/chapter-8

## Question

Write about the factors we should consider while doing component placement.

## Short answer

Group related components by function, position connectors per enclosure, place critical parts like clock and decoupling capacitors first. Consider thermal management, consistent orientation for assembly, and leave routing channels while following manufacturing rules for spacing and test access.

## Answer

Placement decides the quality of routing, noise, heat and manufacturability, so it is done before routing. Factors:

1. **Functional grouping:** place related components together by circuit block (analog, digital, power, RF), in the order of signal flow, to keep traces short; keep noisy and sensitive blocks apart.
2. **Connector and mechanical constraints:** put connectors, switches, LEDs and mounting holes where the enclosure needs them; place I/O connectors at one edge, and leave clearance for assembly.
3. **Critical components first:** place the processor, clock/crystal (close to the chip), decoupling capacitors (adjacent to the IC power pins) and sensitive analog parts first, with short critical routes.
4. **Thermal considerations:** keep heat-generating parts (regulators, power transistors) spaced and with a heat sink/air flow, and away from temperature-sensitive parts like electrolytic capacitors; do not put them in a row blocking air flow.
5. **Orientation and alignment:** align similar components in the same direction for easier assembly, inspection and soldering; polarised parts in a consistent orientation.
6. **Routing and layers:** minimise crossing ratsnest lines; leave channels for traces, and place components on one side where possible (cheaper assembly).
7. **Manufacturing rules:** spacing for pick-and-place, solder (wave soldering direction), and testing/rework access, test points.
8. **EMI and power:** place power entry filters at the connector; separate high-current paths from signals.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which components should be placed first, with short critical routes?
   A. Silkscreen labels
   B. Processor, crystal, decoupling capacitors and sensitive analog parts
   C. Mounting screws
   D. Test points only
   Answer: B. Critical parts decide routing quality and noise; decoupling caps go adjacent to IC power pins. (Key point: Critical components first)

2. How should heat-generating parts be placed?
   A. Next to electrolytic capacitors
   B. In a row blocking air flow
   C. Spaced out with heat sink or air flow, away from temperature-sensitive parts
   D. Under the processor
   Answer: C. Heat shortens life of sensitive parts such as electrolytics. (Key point: Thermal consideration)

3. How should related components be placed?
   A. Together by circuit block in signal-flow order to keep traces short
   B. Randomly
   C. Sorted by part value
   D. Noisy and sensitive blocks adjacent
   Answer: A. Grouping by block shortens traces, and noisy blocks are kept apart from sensitive ones. (Key point: Functional grouping)

## Related in Instrumentation II

- [Factors while routing signal traces on PCB](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aroute-factors) — Instrumentation II, chapter 8, asked 4×
- [Input/output interface unit design factors](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aio-interface-unit-importance) — Instrumentation II, chapter 7
- [Routing factors and avoiding crosstalk](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aroute-factors-crosstalk) — Instrumentation II, chapter 8

## Related in other subjects

- [Material handling and factors to consider](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Amaterial-handling-factors) — Construction Management, chapter 6
- [CT secondary should not be kept open](https://www.bctengineer.com/question.md?key=semester_4%2Felectrical_machines%3Act-secondary-open-true-false) — Electrical Machines, chapter 2
- [Points to consider when establishing traverse](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Atraverse-establishing-points-considered) — Surveying II, chapter 1
- [Points to consider when measuring earthwork](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Apoints-measuring-earthwork) — Estimating and Costing, chapter 2