How to Control PCB Assembly Costs

How to Control PCB Assembly Costs

Each part of a PCB is specific, and missing any component will result in an incomplete product. Every PCB is unique, so the cost of assembling printed circuit boards is influenced by several factors. How to control PCB assembly costs is a critical question for any PCB company. This article will explore various dimensions on how to reduce PCB assembly costs.

Factors Affecting PCB Assembly Costs

  1. Materials Used in PCB Manufacturing: For a standard double-sided board, materials like FR-4 and CEM-3 are commonly used. Board thickness can range from 0.6mm to 3.0mm, and copper thickness from 1Oz to 3Oz. These variations in materials can cause significant price differences. Additionally, there are cost differences between ordinary thermosetting ink and photosensitive green ink, leading to diversity in material costs.
  2. Manufacturing Processes: Different manufacturing processes can lead to different costs. For example, gold plating vs. tin spraying, milling (routing) vs. punching (stamping) for shaping, and using silk screen circuits vs. dry film circuits will all result in varying costs, thus affecting the overall price.
  3. PCB Complexity: Even with the same materials and processes, the complexity of the PCB can lead to different costs. For instance, if both boards have 1000 holes, but one has hole diameters greater than 0.6mm while the other has diameters smaller than 0.6mm, the drilling costs will differ. Similarly, if the line width and spacing on one board are larger than 0.2mm and on another smaller than 0.2mm, production costs will vary. More complex boards have higher scrap rates, which increases costs and leads to price variability.
  4. Customer Requirements: Different customer requirements can directly impact the yield rate at the factory. For example, a board that meets IPC-A-600E class 1 standards might have a 98% pass rate, but only a 90% pass rate if class 3 standards are applied. This discrepancy affects the cost and ultimately the product price.
  5. Different PCB Manufacturers: Even for the same product, different manufacturers may have varied costs due to differences in process equipment and technical expertise. Some manufacturers prefer producing gold-plated boards because the process is simpler and less costly. However, for others, producing gold-plated boards may lead to higher scrap rates, increasing costs, so they might prefer producing tin-sprayed boards, offering lower prices for tin-sprayed boards than for gold-plated ones.

By understanding these factors and making strategic decisions in materials selection, manufacturing processes, and working with the right manufacturers, companies can effectively control and reduce PCB assembly costs.

PCB Assembly Costs

Effective Design Strategies for Cost Reduction

We have compiled effective design strategies that can help you reduce the engineering costs of PCBs.

1.Surface Mount Technology over Through Hole

Switching to Surface Mount Technology (SMT) from traditional through-hole methods is a key strategy for lowering PCB design costs. SMT allows for denser, more compact board layouts and automated assembly, reducing material usage and speeding up production.

This makes SMT a favored choice among cost-conscious PCB designers for its efficiency and potential to decrease per-unit expenses.

2.Space Assessment and Array Design
Enhancing the cost-efficiency of Surface Mount Technology, careful space assessment, and array design in PCB layout optimize board space usage and reduce material costs. Making strategic material choices and evaluating processes ensures that performance needs are met economically.

3.Plated Through Hole Vias

Using Plated Through-Hole (PTH) vias is a cost-efficient approach in PCB design, offering savings compared to pricier via options. Properly balancing their size and functionality and choosing uniform annular rings and optimal hole sizes help minimize costs.

Avoiding filled vias also reduces expenses, leading to a cost-effective and functionally sound design.

4.Cost-effective Material

Choosing cost-effective materials is crucial for reducing PCB design cost. It’s important to select materials that balance performance and cost well and consider factors like batch sizes, exchange rates, and tariffs.

Opting for the right components, whether through-hole or surface-mount, also helps streamline costs, ensuring efficient and durable PCB fabrication.

5.Adjust Trace and Clearance Requirements

Adjusting trace width and clearance specifications is key to cost-effective PCB design. By adhering to industry standards and customizing these parameters to specific design needs, you can minimize material usage and simplify manufacturing.

Collaborating with fabricators for strategic adjustments ensures the design maintains functional integrity and cost efficiency, potentially reducing board size and material costs.

PCB Assembly

Assembly Tips for Completing a Cost-Efficient PCBA

Reducing Component Expenses

Make sure that the components you’re using on the circuit board are not adding unexpected costs by checking for the following:

▶Don’t specify components that are suspected of being illegitimate or counterfeit. These may fail prematurely during ruggedness testing – or worse, in the field.

▶Ensure that the components you use on the board are available and have the best price. With component supply shortages ongoing and allocation in place through many suppliers and distributors, procurement must enact a sourcing plan as soon as possible during development. Design teams can support procurement by offering multiple workable part variants to increase the potential pool to draw from.

▶Check for component life cycles to ensure they’ll be available for the board’s production. Once more, shortages have caused many suppliers to take a long look at product lines to ensure their operations are producing the most valuable chips possible. Expect obsolescence and be prepared to navigate around changes in catalog offerings.

▶Look for ways to reduce the use of expensive components or parts that are difficult to work with by finding alternates or redesigning the circuitry.

 

Making PCB Assembly More Efficient with Good DFM Practices

Just as with circuit board fabrication, there can be excessive expenses in how the board is designed for assembly. Here are some ideas to consider:

▶Make sure to optimize the layout for soldering processes. What may work best for the wave solder could cause problems during solder reflow. These types of issues could result in unexpected rework expenses.

▶Avoid placing components in a way that forces them to be manually assembled. For example, smaller parts placed in the shadow of larger components may have to be installed by hand, which adds cost to the board.

▶Make sure that your component placement provides enough room for debugging and rework on the board. Parts that are difficult to access for the rework technicians will also add to the board’s manufacturing costs.

▶The board must be enabled for automatic testing to ensure it’s been assembled correctly. If the board has not been built as a design for test (DFT), the manufacturer will either add testability or test each board manually.

 

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