PCB Copper Thickness Guidelines

PCBA stack-up will likely be among the last concerns on your mind, whether you’re a circuits designer or an engineer just starting in their profession. When jumping into a design process with full effect and excitement, I’ve seen expert designers finish up completely forget some of the crucial board stackup elements. This has happened to me on more than one occasion. Simple things like PCBA copper thickness and board width can easily be pushed to the side, but you have to think about these 2 points for several applications as not every board would be manufactured on a universal 1.57 mm 2-layer PCBA. Although these 2 points could be pushed to the back foot, you’ll still need to know about them.

When constructing your stack up, it is essential to consider the overall board thickness, the insulation thicknesses of your PCBA, and the thickness of the copper. Because copper thickness may add to the overall thickness of the outermost layer in addition to the solder mask, this is not a point that should be disregarded as unimportant. When is it a good idea to use copper that is thicker than just the standard deviation that your manufacturer has established? If your model deviates from the average values shown in many layouts, there are specific circumstances and PCB layer rules you should consider before doing so.

The PCBA Core

The insulating substance that separates the two deepest copper layers creates the PCBA’s base. It’s an insulating substance that is also referred to as the base. The floor is a copper wrap that makes up most of the width of such a square patch or multi-layer board stack-up. The fabricator by itself doesn’t change the thickness of the core.

Internal layer on the PCBA

More dielectric material inside this interior layer is required to sustain different layers with copper along both sides of the core. The thickness among these internal layers is adjusted to produce the desired final board thickness.

Layers of copper in PCBA

The total thickness of the board is also determined by the number of copper layers, their volume, or their width. This width is also affected by any coating on a copper layer.

Layers of Prepreg In PCBA

Some PCBAs necessitate using two or several cores split by prepreg layers. It is required to improve the rigidity of PCBA but also increase the board width.

Introduction of PCBA copper thickness

The importance of PCBA copper thickness:

The need for Rigid PCBA of a specified thickness is growing in the industries. Standardized thicknesses make it easier to create systems and allow most production lines to make good use of Rigid PCBs, which results in cost savings. The Rigid PCB business produces panels with thicknesses that conform to industry standards of 0.0079 inches, 0.020 inch, 0.016 inch, 0.093 inch, and 0.125 inch. The available standard thicknesses range from 0.3 to 0.8 millimeters, with increments of 0.1 millimeters, then go up to 1.0, 1.2, 1.6, 2.0, 2.4, and 3.3 millimeters. Unfortunately, PCBA designers sometimes resort to creating boards with thicknesses outside the industry norm to satisfy operational needs.

The installation of a printed circuit board can also affect the thickness of the panel. When determining the thickness of their PCBAs, designers consider several things. The following are some key considerations:

Flexibility is an essential factor.
Ability to Caring Current
Materials that are used.
Count of Layers.
Intactness of Signals.
The usage of a conduit.
The conditions in which operations take place.
Mechanical Production Methods.

Comparison between Standard and High Copper Thickness:

The thickness of PCBA copper is 1 oz. Indicates that one ounce of copper by volume is distributed uniformly and flattened across an area that is one sq ft in size. The final copper thickness was 1.37 thousandths like an inch, meaning 1.37 millimeters, to give it its more customary measurement. Manufacturers typically fabricate PCBAs using a copper layer that is 1 ounce thick. The manufacturer shall default to assuming and quoting for just a thickness of 1 ounce of copper except if the client specifies various sizes.

A copper thickness of 1 ounce will be sufficient for most applications. Because manufacturing thicker copper takes longer and is more challenging, the cost of producing the PCBA and the process’s complexity increased the copper’s thickness. Instead, designers often opt to extend the thickness of the copper track just on PCBA to make it capable of carrying a more significant current:

Weight of Copper	Thickness of Copper	Track the width (mils)
1oz/sq ft	1.37 mils	62.5	125	250	250	1000	2000	4000	8000
Current at 20 C (A)		4.6	7.6	12.5	20.7	34.2	56.6	93.6	154.7

How to specify and select the copper thickness of the PCBA:

Circuit board makers and designers may pick from several dielectric materials, including ordinary FR4 (working degree of 130 °C) and ridiculously high polyimide (the temperature of 250 °C). If your project is exposed to harsh environments or extreme heat, consider adopting much more exotic materials; but can the circuit tracing and soldered patch cables survive the harsh conditions?

A test technique has been developed mainly for the printed board sector to verify the heat intmainlych of the final circuit board. Thermal stresses are generated throughout PCB manufacturing, PCB assembly, & repair operations, where variations in the coefficient of expansion (CTE) or Cu and PWB lamination provide an impulse for crack development and propagation, ultimately leading to circuit breakdown. Heat flux testing (TCT) looks for a rising resistance of a circuit when it goes through wind heating and cooling from 25 °C through 260 °C.

Any rise in resistance indicates a breach in electrical stability due to fractures, as in copper circuits. A conventional coupon layout for this test employs a chain of 32 plating through holes, regarded as the weakest spot inside a course while exposed to thermal strain.

The TCT data demonstrate that the failure rate could become unacceptable, regardless of the material. 32percent of the total circuits break after eight thermal cycles on conventional FR4 PCBA having 0.8 to 1.2 mils copper p(a 20% resistance rise is deemed a failure. Panels made from exotic materials significantly reduce the failure rate (3% after eight cycles of Cyanate Ester). Still, they are costly (five to ten times the cost of the material) and complex to produce. A typical surface-mount technological assembly undergoes a minimum of 4 heat cycles before shipment and may experience an extra two thermal cycles per component repair.

PCBA Copper Thickness and Board Manufacturing Costs

In manufacturing printed circuit boards (PCBs), one ounce is the typical thickness of the copper layer. In most cases, ounces are used when discussing the thickness of the copper. What’s the correlation between the copper’s thickness, weight, and cost? When a certain amount of folded copper is used to cover an area of one square foot, this is referred to by the thickness of its copper. Therefore, the total thickness of the copper that results from rolling out one ounce of copper and covering one sq ft would be just 1.37 mils, equaling 0.0348 millimeters.

The thickness of a printed circuit board’s copper lines and, by extension, the copper determines the amount of current it can carry.

Copper must have a thickness mainly determined by the necessary trace width for inrush current boards. Additionally, the element compatibility requirement, the weight of its PCBA, and the kind of connections to be integrated into the board have all been critical aspects to consider.

Copper layers ranging in thickness from one ounce to three ounces are typically used in the production of PCBA. Heavy copper is defined as weighing more than 4 ounces and is utilized for the following purposes:

capable of carrying a higher current
Enhanced resistance to thermal stress and enhanced thermal management are also included.
Enhanced ability to dissipate heat
Greater mechanical strength, making it appropriate for use in big and heavy connections as well as through the components
Power conversion and PCB transformers that are planar

On printed circuit boards (PCBs), the layers will sometimes be created with varying copper layers. For example, its inner layers contain one ounce of copper, while its outer layers contain four ounces of copper. A printed circuit board (PCB) produces heat while it is operating, which can cause the board to warp, bend, or twist. To reduce the impact of this problem, the layer should employ copper of the same weight on layers that are next to one another. For instance, the divergent layer groups on a board with eight layers might look like this: 1 and 8, 2 and 7, 3 and 6, 4 and 5, etc. Therefore, layer 1 & layer eight should contain the same amount of copper, layer 2 & layer 7, and so forth.

Cost:

You must be aware that there will be an effect on both the cost and the production time if the PCBA design demands heavy copper. Of course, copper with a thicker gauge will cost much more than a conventional gauge. Additionally, producing heavier copper involves additional time and money, resulting in a higher production price.

Cost increases due to the following factors:

Choise of Maeterial in PCBA

The cost of a circuit board must necessarily be affected by the components that make it. The FR4 substance used to overlay standard printed circuit boards (PCBs) is also inadequate to produce board panels for increased applications, such as those typical in the aircraft and petroleum sectors.

Size of the PCBA

The dimensions of a PCB and its panel usage seem to be two of the most significant pricing variables. The number of circuits expected for the equivalent device will typically determine the size of a board.

A PCB in a device as tiny as a smartwatch may require fewer parts and, as a result, is less expensive to create than a PCB in a notebook or computer. Similarly, the PCB inside a significant piece of manufacturing equipment will be bigger than most household electronics boards.

Layers in PCBA

Overall, price rises may be divided down into layers like follows:

1-2L: 35 – 40%
2- 4L: 35 – 40%
4- 6L: 30 – 40%
6- 8L: 30 – 35%
8- 10L: 20 – 30%
10- 12L: 20 – 30%

When a 2nd layer is put on a board, a few of the most significant substantial increases in production costs occur. An extra two panels will increase the price by at minimum 1/3 of the prior price. When a design passes the 8th layer threshold, the cost increases become less severe.

Number of holes in PCBA

The diameters of such holes inside a layout are this field’s most essential pricing variables. If the holes are extremely thin, special tools will be required to create them. For example, a hole the size of a hair shaft will be more challenging to construct than even a spot the dimension of a conventional screw hole. Such voids need additional effort and a particular skill set to fill.

The number of holes included in a given layout can affect the price of board manufacture if the gaps remain consistently sized or tiny. Due to the additional labor required, the cost of a board with hundreds of holes would be increased.

The material’s thickness and the number of layers inside the PCB layout are two more hole-related parameters that might impact the cost of PCB fabrication. Because of the thickness of a PCB with ten or even more layers, hole drilling will take longer. The pricing will be affected if the substance is solid and difficult to drill.

Conclusion:

Copper is essential to the total thickness of its PCBA and plays a part in it. In most cases, Copper thickness is determined by the amount of current that flows by the PCBA. Copper layers typically have a thickness of between 1.4 to 2.8 millimeters for inner layers and between 2 and 3 ounces for outer layers. Your desired consistency can be achieved by adjusting the current setting. Be aware that a rise in copper will result in higher pricing and processing difficulties.

Through the use of a track width calculator, one can determine the thickness of the PCB. Enter all the requirements into the calculator, providing you with the required uniform thickness. It is necessary to consider things like the thickness of the solder mask and the prepreg. To guarantee the precision of your measurements, you may do calculations down to one-tenth of a millimeter.

When picking the thickness of the board, keep in mind that a thick board has a lower chance of breaking than a thinner board. If the task requires a narrow board, it is preferable to use a thick one; otherwise, the opposite is true. When determining the thickness of PCBAs.