Name: 8L HDI 2+N+2 Mobile Main Board
Brand: PCB Printed Circuit Board and PCBA manufacturing
Rating: 5 (1 reviews)

Description
Data Sheet

1. Basic Definition of HDI PCB

HDI is the abbreviation of High Density Interconnection. HDI PCB is a high-density interconnected circuit board composed of insulating substrate and conductive circuit layers. As the core electronic carrier, it carries various active and passive components including integrated chips, transistors, diodes, resistors, capacitors and connectors. Through standardized circuit routing and interlayer conduction, it realizes signal transmission, power distribution and functional collaboration between electronic components. Serving as the core mounting substrate for electronic equipment, HDI PCB is the key foundation for miniaturization and high-integration design of terminal products.

This document focuses on 2+N+2 stacked HDI structure, combined with mobile terminal application scenarios, and sorts out professional design specifications for mobile phone PCB and HDI high-density circuit boards.

2+N+2 HDI PCB Structure

2. Mobile Phone PCB Routing Design Criteria

2.1 Power Trace Width & Length Specification

For the battery VBAT power supply line from battery connector to RF power amplifier pins, unified width control shall be implemented according to routing length:

Routing length＜60mm：minimum trace width ≥1.5mm (60mil)
60mm ≤ routing length＜90mm：minimum trace width ≥2.0mm (90mil)

To guarantee stable operating status of RF power amplifier modules, the total extension length of battery power circuit shall not exceed 90mm. All high-current loops shall follow the above width standards; conventional power traces shall be designed with 0.2mm~0.4mm (8mil~16mil) width matched with actual current load.

2.2 Signal Crosstalk Suppression Design

For mutually susceptible signal lines, the line spacing shall be more than twice the single trace width. Overlapping routing of upper and lower layers without ground isolation is strictly prohibited, so as to restrain crosstalk interference and ensure signal transmission stability.

2.3 High‑Speed Signal Routing Rules

High-frequency and high-speed signals shall adopt arc transition routing preferentially. If limited by layout conditions, 135° oblique corner routing is acceptable; right-angle and acute-angle turning are forbidden.

Component grounding pins shall be directly connected to the complete ground plane. Nearby grounding design is recommended, with grounding trace width maintained above 0.5mm (20mil), and long-distance series grounding routing shall be avoided.

2.4 Reinforced Design for Large Components

For large-size devices such as tantalum capacitors and battery connectors, pad teardrop processing or local copper cladding reinforcement is adopted. Adding dense interlayer vias can effectively improve pad peeling resistance and overall structural reliability.

2.5 Board Edge Safety Clearance

All internal routing shall keep a safe distance from PCB outline, with the minimum edge clearance controlled at 0.4mm (16mil), preventing circuit damage and performance abnormality during CNC routing and forming.

3. HDI PCB Technical Standard for Mobile Products

3.1 Core Via Definition

Blind Via: Micro hole connecting outer layer and inner layer without penetrating the whole board, with aperture ranging from 0.05mm to 0.15mm. It is mainly fabricated by CO₂ laser, UV laser, plasma etching and other precision processes.
Buried Via: Inner-layer interconnection via independent of outer layers, featuring larger aperture than blind vias, applied for internal layer conduction of high-density multilayer boards.

3.2 HDI Grade Division & 6-Layer Process Scheme

HDI products are classified by lamination times and laser drilling cycles. 6-layer HDI, widely used in mobile motherboards, is divided into first-order and second-order structures.

3.2.1 6-Layer First‑Order HDI

Standard blind via distribution: 1-2 / 2-5 / 5-6. Laser drilling is adopted for 1-2 and 5-6 outer layer blind holes, while middle layer holes adopt conventional mechanical drilling. With mature process, low manufacturing difficulty and cost advantages, it is widely used in cost-effective mobile terminal products.

3.2.2 6-Layer Second‑Order HDI

Covers multi-group interlayer blind holes of 1-2 / 2-3 / 3-4 / 4-5 / 5-6, requiring two times of laser drilling and secondary lamination.

Process flow: inner buried hole fabrication → first lamination → primary laser blind hole processing → secondary lamination → secondary laser drilling → final mechanical hole forming.

According to via layout, it is divided into staggered blind hole and stacked blind hole structures. Stacked HDI features higher wiring density but higher process threshold; higher-order HDI such as third-order and fourth-order expands performance based on superposition of lamination and laser processes, applicable for flagship high-density motherboards.

4. Maxipcb HDI Core Technology & Product Advantages

Targeting the miniaturization and high integration development of smart terminals, Maxipcb® develops customized AnyLayer HDI PCB for Android mobile devices. Supported by sequential lamination, laser micro-hole processing and via filling technology, the product optimizes wiring density and signal integrity, and meets the comprehensive demands of compact layout, high-speed transmission and low-power design for mobile motherboards.

Comprehensive Advantages

Cost Control: For multi-layer boards above 8 layers, HDI structure optimizes lamination combination and reduces comprehensive manufacturing cost compared with traditional multilayer schemes.
High Integration: Micro blind hole design greatly improves interconnection density, matching the miniaturization trend of consumer electronics.
Strong Process Compatibility: Support stacked via, laser direct imaging and other advanced processes to meet high-end customized design.
Excellent Electrical Performance: Optimized high-speed circuit design to suppress high-frequency loss and ensure long-term stable signal transmission.
High Environmental Adaptability: Strict material selection and process control, adapting to high temperature, high humidity and complex electromagnetic working conditions.
Balanced Thermal Dissipation: Reasonable copper laying and via distribution enhance heat conduction efficiency and reduce thermal aggregation of high-power devices.
Optimized EMC Performance: Perfect grounding shielding design effectively resists EMI, RFI and ESD interference.

5. Quality Control & Engineering Service Specification

Maxipcb implements standardized full-link quality management, complying with IPC-A-600G, IPC-6018A and military-grade certification standards. The company carries out strict engineering DFM review, full-process incoming material inspection, in-process quality monitoring and finished product testing.

A complete after-sales response mechanism is established to ensure stable delivery and reliable quality. Customers are recommended to conduct pre-production technical communication on HDI stacking, blind hole design and high-speed impedance requirements, so as to avoid process risks, shorten the cycle and realize collaborative optimization of design and manufacturing.

As a professional high-precision PCB manufacturer focusing on mobile terminals, high-density HDI and high-frequency boards, Maxipcb relies on complete production lines and rich industry experience to provide one-stop customized PCB solutions for global customers.

Model : 2+N+2 Mobile Main Board

Layers : 8Layers

Material : TG170 FR4

Construction : 2+4+2 HDI PCB

Finished Thickness：0.8mm

Copper Thickness : 0.5OZ

Color : Green/White

Surface Treatment：Immersion Gold+OSP

Min Trace / Space：3mil/3mil

Min Hole：Laser Hole 0.1mm

Application : Mobile Main Board

8L HDI 2+N+2 Mobile Main Board

Description

Data Sheet