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Computer printed circuit board helps components such as RAM and CPU communicate with each other for smooth operation.
These PCBs, including SSD PCBs, HDD PCBs, and HHD PCBs, are used to make connections within PCBs found in storage devices, motherboards, and peripheral expansion cards to facilitate electronic communication and power distribution within the system.
ELEPCB will discuss PC boards, the main circuit board in a computer, and the related components in this article.
The History of Computer Printed Circuit Board
Computer PCB is the main carrier of computer hardware, and its evolution is encouraged directly by the integration of electronic elements, protocol specifications and production technology.
The Initial Stage (1980s-1990s)
During this period, the primary technology is embodied in the single or double-layer board, its wiring density is low, discrete components such as resistors, capacitors predominate. Key protocols were the ISA bus (industry standard architecture) and IDE (Integrated Drive Electronics Interface). The key boards at this time are the Motherboard, which incorporates CPU sockets, memory slots, and ISA/PCI slots; and expansion cards, e.g., discrete graphics cards, sound cards, and network cards, e.g., ISA sound cards and PCI network cards.
While some technologies are being retired, ISA bus with low bandwidth (around 8 MB/s) to be replaced by the PCI bus with 133 MB/s bandwidth; IDE interface also being replaced by Serial ATA (SATA) interface with 6 Gb/s speed.
The Middle Period (2000s-2010s)
The leading technology of this phase is multilayer boards that support more cabling density and can reduce electromagnetic interference (EMI). As for leading protocols, PCIe replaces PCI/AGP as the normal interface for high-speed peripherals and GPUs, while USB 3.0/3.1 replaces legacy serial/parallel ports to support data transfer rates of 5 to 10 Gbps. Of the required boards, motherboards host built-in SATA controllers, Gigabit Ethernet PHYs, and PCIe x16 slots; GPUs are separate PCBs requiring PCIe x16 support and high power supply.
Replaced technologies are PCI/AGP slots completely replaced by PCIe, PS/2, VGA ports replaced by USB-C, HDMI/DisplayPort.
The Current Stage (2020s to present)
The most significant technologies during this stage are High Density Interconnect (HDI) and Any layer interconnect, which can process more than 10 layers of PCB based on microvia and laser drilling technology, thus making ultra-thin design possible, e.g., in the application of laptop computers. In case of PCIe Gen5/6, high-speed signaling design the speeds are 32 GT/s and above for which strict impedance matching and control of loss has to be used, e.g., the utilization of Low-Dk materials; DDR5 memory requires equal length cabling as well as differential-pair design for signal integrity. Regarding the main boards and parts, the primary components of the motherboard are CPU socket (LGA 1700/AM5), PCIe Gen5 slot, USB4/TB4 controller, and its power system utilizes a multi-phase VRM (Voltage Regulator Module) to support CPU/GPU overclocking, for example, 20 +phase power supply; the GPU PCB adopts a 12-layer or more HDI board with embedded GDDR6X video memory and PCIe Gen5 interface; NVMe SSDs utilize M.2 interface PCBs and support PCIe Gen4/5 x4 lanes (8-16 GT/s).
There are some replaced technologies, SATA SSDs have been replaced by NVMe SSDs with the difference in speed of 5x or more, and some of the traditional cooling solutions have been replaced by Vapor Chamber and Graphene Thermal Membrane.
| Stage | Tech | Protocols | Circuit Boards | Replaced Tech |
| 1980 – 1990s | Single /double layer boards, discrete components dominant | ISA, IDE | Motherboard (including CPU socket, etc.), expansion cards | ISA, IDE related |
| 2000 – 2010s | Multi-layer boards | PCIe, USB 3.0/3.1 | Motherboard (including various components), GPU PCB | PCI/AGP, PS/2, etc. |
| 2020s – now | HDI/Any layer, high speed signal design | N/A | Motherboard (including various components), GPU PCB, NVMe SSD | M.2 interface – related, part of traditional heat dissipation |
The Main Circuit Board in a Computer:
HDD, SSD and HHD
HDD PCB
HDD PCB is a dual-core ARM/DSP chip, with the ARM doing logic control and the DSP handling servo position. It contains an embedded preamplifier IC, which enhances the signal-to-noise ratio for sub-µV head signals. The architecture also includes Adaptive Vibration Compensation Circuitry (AVC), which compensates for mechanical vibration errors in real time using piezoelectric sensors.
SSD PCB
The SSD PCB offers a three-tiered storage hierarchy with an SLC cache layer (1-2GB capacity), a TLC/QLC main memory, and OP reserved space. It supports 176 layers of 3D NAND stacking and uses Flyover cabling to reduce signal delay. The hierarchy also includes an LDPC error correction engine (>120bit/2KB error correction) and a dynamic thermal management unit.
HHD PCB
HHD board employs a heterogeneous computing platform based on an FPGA and a mechanical control unit (MCU) as its compute design. A smart data triage system that automatically migrates hot data that is accessed frequently (over 15% of access) to the 8-16GB XPoint 3D cache.
Power management is through a hybrid mode in which automatic switching into SSD power mode is done when mechanical components are inactive and 40% power savings occur.
| TYPE | FULL NAME | DETAIL |
| HDD PCB | Hard Disk Drive PCB | Hard disk mechanical control board, integrated motor drive, head positioning, data conversion, and other mechatronic control modules |
| SSD PCB | Solid State Drive PCB | All-semiconductor storage control boards that include the master control chip, NAND flash memory array and power management module |
| HHD PCB | Hybrid Hard Drive PCB | Hybrid disk hard boards, composite circuit systems with HDD mechanical control modules and SSD flash cache modules |
| ASPECT | HDD PCB | SSD PCB | HHD PCB |
| Core Components | Spindle Motor Drive IC + Voice-Coil Motor Controller + Head Amplifier | Main control SoC +DRAM Cache +NAND Array | HDD Control Module +Flash Controller +Data Cooperative Processing Module |
| Interface Standard | SATA/PATA (up to 6Gbps) | SATA/NVMe (up to 32Gbps) | SATA + On board PCIe Channel |
| PCB Layers | 6-8 layers (electromagnetic interference isolation) | 4-6 layers (high speed signal integrity) | 8-10 layers (mixed signal isolation design) |
| Power Consumption Characteristics | Typical 5-7W (including motor drive) | 2-3W (no mechanical parts) | 4-5W (dynamic power consumption regulation) |
| Vibration Indicator | 60G/2ms (mechanicall protection design) | 1500G/0.5ms (all solid state structure) | 300G/1ms (dual-protection mechanism) |
| Parameter | HDD PCB | SSD PCB | HHD PCB |
| Line Width / Spacing | 75μm / 75μm (conventional manufacturing process) | 50μm / 50μm (HDI process) | 60μm / 60μm (hybrid process) |
| Impedance Control | 100Ω ± 10% (differential signal) | 85Ω ± 5% (NVMe high – speed signal) | 90Ω ± 8% (composite signal requirement) |
| Heat Dissipation | Local copper foil thickening (1oz → 2oz) | Whole board copper substrate + heat conductive adhesive filling | Zoned heat dissipation: thick copper in mechanical area + heat conductive pillars in flash memory area |
| Reliability Test | 1000 hours of high temperature and high humidity (85°C / 85%RH) | 3000 times of temperature cycling (- 40°C → 125°C) | 2000 hours of mixed environment test |
PC Board Components
To achieve computer printed circuit board components, the basic components, and why? You may need to learn what NVMe-oF (NVMe over Fabrics) is prior to learning what each does.
NVMe-oF is a network protocol addition to the NVMe (Non-Volatile Memory Express) protocol for remote access to storage on a network such as Ethernet, InfiniBand or Fibre Channel. It significantly accelerates data center and cloud storage performance by implementing the low-latency, high-throughput attributes of NVMe in distributed storage systems.
NVMe-oF requires high-speed signal-capable PCBs (e.g., 25G/100G Ethernet or PCIe Gen4/5), multilayer boards, impedance control, low-loss material and advanced signal integrity designs.
- NVMe-oF is currently an up-and-coming technology in the storage realm, and is gaining broad adoption very quickly especially in hyperscale data centers and AI/HPC applications.
- The NVM Express Inc. controls the NVMe-oF specification and updates it to accommodate additional transport layers (e.g., TCP/IP, RoCEv2) and features (e.g., multipathing, security patches).
- Major vendors (e.g., Intel, Samsung, Dell) have introduced hardware solutions for NVMe-oF to encourage adoption in enterprise SSDs, all-flash arrays.
High Speed Interface Controllers
PCIe Retimer/Redriver
- PCIe Retimer/Redriver can compensate for signal degradation under high-speed transmission such as PCIe Gen5, Retimer can re-timer the signal and Redriver can enhance the driving ability.
USB4/TB4 PHY
- USB4/TB4 PHY supports 40 Gbps data transmission and DisplayPort Alt Mode for high-speed data and video signal transmission.
Power Devices
DrMOS (Driver MOSFET)
- DrMOS integrates driver and MOSFET to reduce parasitic inductance and resistance and improve VRM efficiency.
GaN (Gallium Nitride) Power Devices
- GaN is used in high-density power designs such as laptop charging modules to achieve high power conversion efficiencies in small packages.
Passive Components
High Frequency MLCC (Multilayer Ceramic Capacitor)
- High-frequency MLCCs with low ESR are used for decoupling and filtering to filter out high-frequency circuit noise.
High Q Inductors
- High Q inductors are used for high efficiency DC-DC conversion to reduce energy loss.
Computer PCB Technologies You Need to Know
Computer PCBs involve a variety of technologies and materials. In terms of materials, Low-Dk/Df materials (e.g. Panasonic MEGTRON6, Isola FR408HR) have lower Dk and Df values to reduce high-frequency signal loss, and thermally conductive substrates (such as aluminum substrates in metal-core PCBs) can be used to dissipate heat from high-power components. In terms of fabrication process, the semi-additive method (mSAP) is able to achieve 3/3μm line width/space, which is used for CPU/GPU package substrate fabrication; and the buried component technology saves space by embedding resistors or capacitors inside the PCB.
| CLFS. | Detail |
| Material | Low-Dk/Df materials: low Dk and Df values to reduce high frequency signal loss Thermally conductive substrates: for heat dissipation of high power components |
| Fabrication | mSAP: realizes 3/3μm line width/line pitch for CPU/GPU package substrate manufacturing Buried Component Technology: Embedding resistors/capacitors inside the PCB saves space |
Conclusion
The past of computer PCBs has always been one of high power, high density, and high speed. Technologies such as NVMe-oF have driven PCB technology forward in signal integrity and materials, and standards such as PCIe Gen5 and DDR5 have defined the technology boundaries of current designs.
As technology progresses comes the heavier and heavier dependence on computer circuit boards. The motherboard that ties everything together, the SSD PCB that helps accelerate storage, or the HDD circuit board that controls old hard disks, these printed circuit boards are required for the computing experience to function smoothly.
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