BILL OF MATERIAL

 

Bill Of Material is nothing but to add all the information of your components used in the PCB designing in a paper including their name, part number, specification, value, and cost

BOMs are used everywhere, not just for PCBs. If you’re working in any engineering domain that involves a product being physically built, then you’ll be using a BOM. 

Trying to keep track of every part number in your head or on a scratch piece of paper will soon be impossible.

The truth is if you want to make anything of your PCB design skills than learning how to create and manage a Bill of Materials is a necessary venture. And at the end of the day, spending the time to make a complete list of parts will make your life all that much easier when you know exactly what needs to be ordered for your design now and in the future. So what kind of information needs to be included in your BOM?

 

REFERENCE DESIGNATOR

 

This is how your components are uniquely identified on your PCB layout. For example, resistors are labeled R1, R2, etc.. and integrated circuits will be labeled U1, U2, etc… Including this information in your, BOM will allow you to easily cross-reference information between your BOM spreadsheet and PCB layout.

 

COMPONENTS VALUE

 

This is the unique value of your components and will be specific to the part in question. For example, resistors have a value of their resistance; capacitors will have a value of capacitance, and so on. Having this information organized up front will make it easy to find the right value for a part you’re searching.

 

MANUFACTURER PART NUMBER

 

The part number is the unique identification number provided by a component distributor. This information alone is what you or your manufacturer will need when ordering a part, so it’s super important to make sure these numbers are accurate and up to date.

 

 

QUANTITY

 

Pretty obvious here, the quantity will list exactly how many of a particular component you need to order. Keep in mind that some components can only be ordered in bulk from a distributor so that you might wind up with extras.  There are also value discounts that will help save some money.

 

DESCRIPTION

 

Each part will need its own unique description. This will help to narrow your search options by knowing exactly what kind of resistor, LED, capacitor, etc. to look for in a part distributor’s database.

 

PACKAGE TYPE

 

Surface Mount (SMD) components are made with a specific package type to make the manufacturing process  efficient. You might have already seen these package types while finding parts in Autodesk EAGLE. LIKE SIP, QIP, or SOP . Be sure to make a note of the package type when adding SMD components on your BOM.

 

PLACEMENT METHOD

 

The placement method will tell you or your manufacturer how the part is going to be assembled on your board. Are you working with through-hole components? Or maybe a combination of through-hole and SMD? Be specific here; your design depends on having the right component assembly type.  

 

 

Here’s a Plated Through-Hole (PTH) and Surface Mount Device (SMD) component side-by-side. 

 

TOP/BOTTOM

 

This one is simple – is the part going to be assembled on the top or bottom of your board? On simple designs, you might have all of your parts on the top layer. As your board shrinks and your designs get more advanced, you might find yourself placing parts on both the top and bottom layers.