In this article we will be considering the functions of the copper layer in PCB. We’ll also discuss how you can generate the output files for your copper layers and more.
Why is Copper Used in Printed Circuit Boards?
Two terms are very important for use in the PCB design.These include copper thieving and copper balancing. Though, they are usually used interchangeably, we will explain the important distinctions between them:
Copper balancing involves the addition of non-conductive patterns and areas of copper into a printed circuit board. This alleviates the board’s possible bending when manufacturing is on. Furthermore, the PCB layer stackups, which aren’t configured symmetrically, can lead the warping of the board during fabrication.
Also, the uneven copper present in the structure of the board could also twist when the process of assembly as a result of too much heat utilized for soldering.In order to counter this, your design system of the PCB CAD will help in adding the area fills, and pours, to the board’s sparse areas to help copper balance your design.
Copper thieving is adding non-conductive copper patterns to the printed circuit board. However, in cases like this, it is either to thieve or even out some electrical current utilized in the plating of the board. Also, on the board areas where there are lonely or isolated traces, the applied current onto the board to aid plating could be more concentrated or focused on the features.
The scenario could cause the trace to under-etch thereby delivering a kind of “mushroom” profile rather than the clean squared edges expected. The trace’s cross-section can depict serious undercutting, the trace present on the right side is squared off the way you want.
Choosing the Right Material for the PCB Copper?
This is known as the cathode part of the electrolytic material. This material is deposited onto a continuous, thin, metal foil layer on the circuit board’s base. Furthermore, you can bond it easily onto an insulating layer, thereby accepting a protective layer, as well as corroded in order to form your circuit pattern.
Prepreg is culled from the word pre-impregnated. This is known as fiberglass that is impregnated with resin. This resin is pre-dried;however, it isn’t hardened. Therefore, when heated, it sticks, flows, and is fully immersed. Therefore, the prepregs are strengthened with fiberglass through an adhesive layer, which is just like the FR4 material. All the names of the prepregs are obtained from the fiberglass used.
What is the standard Thickness of the Copper Layer in PCB?
One of the mostly used units when measuring thickness of the copper layer in printed circuit boards (PCBs).However, majority of people don’t have an idea about the nature of its thickness. Sure it is not everyone that thinks it in mils and then converts into their preferred measuring unit using a unit conversion tool.
Furthermore, majority of PCBs are usually constructed using a copper thickness of 1 oz.During PCB manufacturing, when the customer doesn’t offer their specific specs, then the manufacturer usually assumes 1 oz whenever they are quoting as well as building the design. Furthermore, if the customer decides that their design needs additional current than the usual 1 oz could carry, then it is advisable to increase the thickness of the copper, as well as your traces’ widths.
Sure, the thicker your copper is, then the more the cost. However, there are some certain time when this becomes necessary. Also, the increase in cost doesn’t have to do with the costs of raw materials only but that the processing of thicker weights of copper consumes more time. Also, it is a bit trickier to perform or handle.
Processing the Thickness of the Copper Layer in PCB
Etching helps in manufacturing the board’s copper traces. This is the same whether it is for the internal layers or for the surface. Etching is one important step in PCB manufacturing. The layer fabrication starts with the laminate sheet, which is fully covered with copper. Etching has to do with getting rid of the excess copper that is present in traces, as well as other areas, like annular rings for the vias, component pads, making use of ammonia-based solution.
The sheets typically start with the copper thickness. The thickness could be etched down, increased, plated up, or decreased to the right specification. As a result of these sheets’ manufacturing process, the surface features a kind of roughness, which assists with the bonding to a specific dielectric material. Moreover, this could result in an adverse and negative effect on the signal integrity at a higher frequency.
Furthermore, at a frequency of more than 100MHz, this skin effect whereby current flows is usually close to the trace’s internal surface in contrast to the through the center of the conductor. This leads the trace’s effective resistance to rise and then oppose the flow of current.
How to Generate the Output Files for Your Copper Layers
Anytime you generate output data files, make use of “flashes” for the pads. This avoids pads that are “painted/drawn”.
Furthermore, for the larger copper planes or copper areas don’t fill them with using small draws or “painting”. Anywhere possible, make use of polygons or contours in constructing planes or areas. They are the standard features present in the Gerber X2 output and other data formats.
In addition, make sure that you add your board outline whenever you output the copper layer in PCB. This aids in the identification of any rotation, data alignment, as well as mirroring issues.
Achieving this is best making use of a specific small line, whereby the line’s center is the board outline.
We hope we have explained what the copper layer in PCB is all about. We are always here to assist you, if you have any questions.