Bare board cost

Question

Bare board cost

Accepted Answer

In determining the bare printed circuit board assembly cost, this involves the price, quality, and delivery time of the raw materials, which focuses on their type and thickness, PCB size, and layer count.

Raw Material Type and Thickness

When it comes to PCB types, there are two different types such as rigid PCB and flex PCB. Flexible PCB assembly’s cost is more expensive compared to the rigid PCB board. For the latter, many material types may be available for use to produce a PCB. The most basic is called FR-4. FR-4 consists of a fiberglass and material combined together with an epoxy resin known for its fire-resistant features. Other types include higher temperature FR-4, polyimide, hybrid capable, high copper weight, and flex PCBs that may be chosen to produce high copper weight, hybrid capable PCBs or other types. In general, the most basic material thickness is 0.062-inch. The careful selection of the different material types and thicknesses has a critical effect on the manufacturer’s PCBA price.

Board Size

The printed circuit board’s size is a huge factor that contributes to the PCB assembly services’ production cost. A bigger board size means you need more raw materials to use. This is a vital factor that can impact the overall cost of printed circuit board assembly production. In some instances, based on the client’s specifications, the PCB is built in distinct requirements and this can be costly. In most cases, one dimension is better compared to the other. At times, clients are very particular about their panel requirements. A panel is a larger printed circuit board that has many mini boards that should be divided before using them. Automated printed circuit board handling equipment usually encounters issues with smaller boards, especially when putting several boards together at once, although the process can speed up if necessary. A panel is a vital raw material to create a printed circuit board assembly. The printed circuit board size or the space of the “real estate” it employs up on a panel is a significant factor in estimating the cost/price. It may look simple but, in reality, it can be a complicated thing. For instance, although the dimensions require a PCB that uses less real estate, it may be higher in cost when producing it. The reason behind is the overall panel size needed to manufacture the board. One dimension is more suitable for one panel compared to the other. Let’s take an example, we have two parts with exactly similar total square inches per board. The first is 2-inch x 6-inch while the second is 3-inch x 4-inch. A standard production panel for a PCBA can have more of the 3-inch x 4-inch board as compared to the 2-inch x 6-inch board. So the cost per board would be reduced in the 3-inch x 4-inch board.

Layer Count

The number of layers is a cost-determining factor. Single-sided or double-sided PCBAs are of the same cost to produce. However, multi-layer PCBAs create additional costs in the materials and manufacturing process. Generally, moving to a four-layer PCB from a two-layer PCB assembly can make the price to double. Adding more layers to a multi-layer project requires additional cost but the price increase related to putting more layers is not as obvious. For example, the cost to go from 4 layers to 6 layers may represent a 50% increase as opposed to the 100% increase incurred when shifting from a 2-layer to a 4-layer PCB assembly. In essence, adding layers to the production process will incur an added cost. More layers in the printed circuit board assembly are one factor that is calculated to identify the total PCBA cost. Whether it is a single layer, double layer, quadruple layers or multi-layer printed circuit boards, the prices variation is dependent on the number of raw materials.

Quantity and Lead Time

Quantity and lead time are important in identifying the estimated PCB assembly services cost. You can’t expect that every piece used in the prototyping stage will be as is during the mass production stage. In the prototype or small batch production, there is a required added engineering cost, such as the costs of processing file, stencil, changing SMT line, etc. As a rule of thumb, when smaller quantity and shorter lead time are requested by the client, the cost per unit is usually higher. In terms of quantity, most manufacturers provide a minimum cost for every order. For instance, if you only need 10 pieces for your project, the minimum order cost will require you to pay 20 pieces. As the quantity increases the cost per board is reduced until the minimum manufacturing cost is achieved. Quantity is a critical factor when identifying the PCB assembly cost drivers. Bulk orders are more efficient for the PCB assembly services providers in offering great discounts as they can increase the production level aside from reducing the product cost. Some manufacturers will provide higher quantity discounts but deliver smaller quantities over time. For example, a 500-piece order may be placed with 100 pieces delivered each month until the order has been completely fulfilled. In this case, the manufacturer achieves manufacturing efficiency by producing all 500 pieces at the same time and the customer achieves cash flow efficiency by only paying for the product that has been delivered. In terms of lead time, the old adage, “Time is money,” rings a bell for PCB assembly services providers. The faster a project needs to be produced means it will be more costly – usually between 30% and 200% more. For a PCB assembly manufacturer, there are real costs involved with prioritizing new projects more than the currently existing task. Some of the costs are reflected in the total pricing.