![blueprint pcb stack-up blueprint pcb stack-up](https://www.allaboutcircuits.com/uploads/articles/common-layer-stack-ups-for-a-four-layer-board_Mahdi_AAC_image3.jpg)
When you send your PCB for manufacture, all of this information is normally then exported in a manufacturing document to accompany the Gerber files.BluePrint-PCB® works your PCB CAD system and/or CAM350® to help you quickly produce comprehensive electronic drawings to drive PCB fabrication, assembly and inspection processes. It can also then automatically choose the best via range to use when vias are dropped during board routing. Normally, the EDA tool can help you with this and will prevent you from creating a drill pass that is incompatible with the stackup option you have chosen. Once the layer stackup is confirmed the next step is to define the via ranges you plan to use. This information is not only useful for the fab house but can also be used by your EDA tool layer thicknesses, for example, can be used to include drill depth in length matching calculations. This is also the place to specify the materials, thicknesses and dielectric constants for your PCB. Therefore, when designing a multi-layer PCB the most important thing is to think through your required via usage and get the layer stackup configured in your EDA tool right at the beginning. You cannot for example have a buried via between Inner 1 and Inner 2 if your 4-layer stack is constructed with external layer pairs. We can see from this that the layer stackup dictates available drilling ranges using standard manufacturing techniques. For example, in the 4-layer board discussed earlier you could have three drill spans in the case you were using two cores (external layer pairs) or two drill spans in the case you were using one core (internal layer pairs). This means that, having set up the layer stack there is a known legal set of drill spans which are possible. When a multi-layer PCB is constructed a separate pass of the CNC Drilling machine is required for each drill span. Unsurprisingly, this is normally referred to as internal layer pairs because the cores are built from the inside out. Then a layer of prepreg/foil is placed on either side of the board, this is cured, etched, drilled, plated. Most PCB design software, including the Proteus Design Suite, refer to this type of stackup as external layer pairs because the cores are built from the outside in.Īlternatively, you can use one core which is drilled and plated. You can use two cores, individually drilled and plated and stuck together with pre-preg and then a final drill/plate pass: With a 4-Layer board there are basically two ways to create the stack. Let's take a closer look using a 4-layer board as an example. This process creates a basic set of rules as to what is manufacturable using conventional processes, in particular for drilling. Multiple layers of pre-preg can be used together to make up thicker insulating layers.
![blueprint pcb stack-up blueprint pcb stack-up](https://mxcdn.macrofab.com/wp-content/uploads/2018/09/MF_2_Layer_Stackup.png)
They will then overlay the board with pre-preg, then either bond that to another core (this core could be a basic core or already have had additional layers of pre-preg and copper foil) or a foil. They will drill, through-hole-plate and etch, one or more of these cores.
![blueprint pcb stack-up blueprint pcb stack-up](https://www.pcbmay.com/wp-content/uploads/2021/06/6-layer-PCB-stackup-3.jpg)