WHAT IS A PCB

PCBs are the most important part of any electronics product or project or a building block, PCBs are a sandwich of a few different materials, for a basic 2 layer 1.6mm board you would generally have a stack-up of Top Solder Mask, Top Copper Layer, Core (FR-4), Bottom Copper Layer and then Bottom Solder Mask, the number of copper layers will increase proportionally with the number of layers. PCBs have lots of little copper tracks to conduct the power.

PCBs have two complementary functions, one being to electrically and mechanically affix them to the PCB which can also aid in thermal conductivity, and two being to provide reliable electrical connections and reliable open circuits along with controlled impedance for high-speed traces or RF. Nowadays we have a large choice of PCBs between standard Rigid boards, Advanced Rigid boards, flexible boards, Rigid-flex boards, and Aluminium boards.

PCBs can range from a single layer to 100 layers, with most phones and laptops using upwards of 16 layers to accommodate for lots of signals along with different surface finishes, like ROHS Lead-free, leaded HASL, ENIG Immersion gold or Immersion Silver and even hard gold!

All of these types are available at PCBWay for quick manufacture!

HOW TO CHOOSE YOUR PCB

We’ll suppose that the user has the need to create a simple amplifier as in the following circuit:

For this, the user will generate a PCB design as the following:

Before ordering the PCB the user will face some choices that have to be evaluated.

Board Type. Board type is the different types, for example, single layer board, double layer board, Flex PCB, Rigid-flex. All of these different types have different uses, for example, most PCBs are single, double layer boards which is a non-flex boards, the flexible board is like an FFC cable, flexible base with traces and components soldered, and rigid-flex is a board with parts that are rigid and flexible parts to connect each rigid part.

The default type, for most projects is single or panel, our reference is a single board.

Layers. The number of conductive layers. The layers number depends on how complex the PCB design is. If this has connections that are crossing, your design must foresee more layers and the user will provide a design for each layer.

The default value, for projects like our reference above, most designs nowadays are 2 or more layers.

Material. Base material for the PCB. FR-4 is the cheapest material, but it has lower conductivity compared to the other. Aluminium is more expensive than FR-4 but is only mainly used on PCBs requiring large heat capacity, like a torch with lots of hot LEDs. Rogers is very important when you need low electrical signal loss, can improve impedance control, and better performance when carrying high frequencies. Copper is similar to Aluminium board but has better thermal capacity.

The default material, for most projects, is FR-4, our reference is FR-4

FR-4 TG. Only applicable to PCBs using FR-4 as base material. FR-4 TG is the glass transition temperature for the core material, PCBWay is offering TG150-160 for free instead of TG130-140. The meaning of TG or glass transition temperature is when the internal fibreglass turns from a solid state to a soft and rubbery state, this is important for any high heat application.

The default TG, for most projects, is TG130-140 but with the free upgrade by PCBWay you can get TG150-160 free of charge.

Thickness. Thickness is how thick your board is, this value doesn’t change when ordering PCBs apart from if you have an edge connector where the pins are on either side where thickness is vital, if you have an edge connector consult the datasheet for information. Layers can affect the thickness, for example, a 100-layer board cannot be 0.8mm

The default thickness, for most projects, is 1.6mm

Min Track Spacing. This means minimum width between any conductors between two adjacent traces, the smaller the number you go the more expensive it gets.

The default Min Track Spacing, for most projects, is 6/6mil, but for high-density boards, changes can be made.

Min Hole Size. This means what is the smallest hole size on your PCB for mounting, etc. This excludes vias but includes any other drills.

The default Min Hole Size, for most projects is 0.3mm.

Solder Mask. This is the colour of the mask on the PCB, this is purely cosmetic unless you choose no solder mask that may cause shorting when soldering, there is generally no cost differences for the standard colours like green, red yellow, blue, white and black but there can be a lead time increase for any colour other than green due to longer drying process.

Moreover, if you want to make your design more special, PCBWay also provides novel solder mask like pink, grey, orange and transparent and so on.

The default Solder Mask colour is green for most projects but as stated above whichever you wish.

Silkscreen. This is the colour of the ink printed on the PCB to identify components, similar to solder mask this is purely cosmetic, but removing silkscreen entirely can incur adverse effects, eg. Do not know where to place components during placement.

The default Silkscreen colour is white for most projects but purely cosmetic.

Edge Connector. This enables being able to bevel the edge connector and plate just the connector with a better surface finish like hard gold, if you choose hard gold you are able to choose the thickness of the gold.

The default Edge Connector isn’t needed for most boards and if you need this you will know exactly what you will need.

Surface Finish. This is what metals will be added to pads to improve solderability, when choosing these options tick the setting that says: Tick means you accept we might change "HASL" to "ENIG" at our discretion without extra charge.

Via Process. This is useless for most boards if you are using gerbers as when being manufactured the gerbers are more important than these settings, this is a mostly redundant setting so leave it whatever it sets as it will not impact the PCB.

Finished Copper. This is how thick the copper is on the board, this is measured in ounces, so 1oz is 1oz per 1 foot of PCB material.

The Default Finished Copper is 1oz for most projects

ORDERING THE PCB

In this chapter, we’ll show you how to order your PCB with PCBWay.

At PCBWay it is very easy if you have your gerbers already in a .zip or .rar file, if your files are in this package, go to https://www.pcbway.com/QuickOrderOnline.aspx and select + Add Gerber File

After selecting the .zip or .rar file all the parameters should automatically import, but always check as sometimes these settings can not go into the file. Use the integrated Gerber viewer to make sure they look alright, there can be random discrepancies which you can disregard.

If you are doing a 4 or more layer board it will ask you which files are on each layer, you should be able to find this information in your EDA/design software, as for KiCad it will show the layers in order top to bottom which you can write into PCBWay,

After checking the parameters, you can check the estimated shipping cost and then select Save to Cart

This is where you may have to reupload the .zip/.rar file

Once doing that you can select Proceed to checkout you should be brought to the screen shown below

Check your shipping method and if that is set correctly select Place Order where you will be brought to the payment screen where you will choose a payment method and then fill out details, once you pay for this your order will be placed where manufacturing will start! You can track the status of manufacturing, 2 layer boards should take 24-32 hours, 4 layers can take 48-72 hours!