Having designed 7 different 1000+ part circuit cards in 2.5 years, you come to learn how circuit cards are laid out and some of the regulations around them. Today as the first Circuit Board Break Down, Tinee9 is going to take a look at a graphics card.
Reason why to start with a graphics card….well they tend to have a lot of different engineering sectors that other consumer electronics may be missing like a bike odometer, keyboard, or arduino uno.
Sections to Identify:
5.Types of Components
6.# of Layers Board is Made of
7.Types of Vias
8.Unique Copper Traces
Note:This is not a complete list of everything that can be analyzed, but it hits the major sections of a PCBA (Printed Circuit Board Assembly) design.
Section 1: Connector Types
I would like to say most electronics have connectors on them for various purposes. Those purposes are Power and I/O. ( I/O has many sub-categories)
Below shows what types of connectors and what they interface to.
Section 2: Power Supplies/EMI Filters
A lot of electronics that are not handheld and have to plugged into a device that connects to a wall outlet, generator, or battery producing a substantial amount of power >1 Watt, typically need to follow FCC, or other electrical standards. These standards not only help protect the circuit from unwanted signals, power, frequencies, voltage spikes, etc from disrupting its functions. In addition to self protection, the electronic is not allowed to produced those same unwanted signals either that would disrupt other electronics.
So, how can you tell what a power supply/EMI (Electromagnetic Interference) filters are? Well you look for inductors, and capacitors near by a power connector. Power connector is in the top right corner of the pictures below.
If you hover over each picture a caption will tell you what each box represents.
Now you know what to look for, when identifying power supplies/EMI Filters.
Section 3: Processor/Micro-controller/FPGA
Most electronics now a days have a brain/computer that tells the device what to do. That brain can be of many forms such as; Processor, Micro-Controller, or FPGA as a few types.
These brains have software/firmware/code/instructions that are programmed in telling it what to do when a certain events happen. Computers are mostly dumb and only do what you tell it to do but now we are getting into the age of A.I. (Artificial Intelligence) which can learn and do things on their own. But this graphics card is dumb in comparison to A.I.
Above are two brains each performing a different function:
Left Image: Most likely performs a power supply control to allow the graphics card to go into low power mode or all out performance mode.
Right Image: Big square block in the middle is the Graphic Card Processor or FPGA. I can’t tell or know what type of brain computer graphics card typically use.
4. I/O (Inputs/Outputs)
Next, determining what kind of I/O are coming into and out of the board. We know that there are signals for power, PC monitor signals going out from the PCBA, PC mother board signals, Fan control signals, and some other signals I currently can’t identify.
5. Types of Components
Determining what kind of components are on the board are critical on knowing how the board works and what the circuit board interfaces to. Basic component definitions:
1. Resistors R#
2. Capacitors C#
3. Inductors L#
4. Transistors Q#
5. Diodes D#
6. ICs U#
7. Oscillators Y#
8. Connectors J#
9. Test Points TP#
If you would like to know what each of these things are I will make another article talking about each component type. Below are some pictures with captions of different types of components.
For a graphics card not only is there a brain but there typically is memory to store values until they need to be recalled. Below are pictures of those circuit elements. For this card there are 8 ~500MB RAM Chips totaling 4 GB of Memory. Some IC chips you can read their part number and then look up there specifications online to help you figure out their function on the PCBA.
6.# of Layers Board is Made of
# of Layers of a PCBA can tell you how complex, density, component package types, or Lots of or Not many signals on a board.
For this Graphics Card I could not get a clear picture but a PCBA is layered fiber glass and copper. # of copper layers is what we are looking for. Most simple circuits have 2, but this graphics card has up to minimum of 8 layers that I could tell.
This means that there are a lot of signals running around on the board or there is a IC that uses Ball Gate Array for Soldering onto the PCB which typically means it has a lot of signal it is trying to get onto the PCB. For this case the Graphics Card Processor/FPGA is a Ball Gate Array Chip and most likely has over 100+ signals running out from underneath the chip. One would need many layers just to get that many signals to the rest of the PCBA with out causing shorted circuits.
7. Types of Vias
This is another hard one to show on pictures but vias are copper traces that run between layers and connect the layers together.
1. Through-hole via- connects all layers together
2. Blind via- connects an outside layer to an inside layer
3. Covered via- Connects only inside layers
This graphics card may have all three. Covered vias are the hard to identify since you can not typically see them from outside looking at the PCBA.
8. Unique Copper Traces
Typically copper traces on a board are straight and have may have some bends in it, skinny or wide, or they zig-zag a lot.
1. Straight and may have some bends- normal signal
2. skinny- low current signal/higher resistance
3. wide- high current signal/low resistance
4. zig-zag- a calculated impedance added to the circuit to balance signals (Frequency sensitive signals)
9. Power Planes
Power Planes are large areas of copper and they represent high power signals, ground/reference signals, voltage signals. These power planes are used to dissipate heat from the board quickly so the board does not malfunction/catch on fire. In the below picture, where Q3, Q2, or R15 designators are at are on top of planes. These are useful so if you need to test a voltage you can go quickly go to these point and find a ground plane or voltage plane.
Hope you enjoyed this article and feel free to follow my blog as Tinee9 will be performing more of these break down PCBAs to help identify the 9 sections above.