10 Layer High Speed PCB for 400G Optical Module | Process Breakthrough to Boost Yield

Project Overview

This project is custom 10-layer PCB for 400G optical communication transceiver module. High-speed optical module PCBs require ultra-precise differential impedance control, low signal loss and excellent layer alignment. The previous supplier suffered low yield and long lead time, which threatened customer mass production schedule. JQPCB developed targeted process breakthroughs to solve these challenges.

Core Technical Requirements

1. Stackup: 10 layers
2. Material: M6 low-loss high-speed laminate
3. Board thickness: 1.2mm
4. Controlled differential impedance ±5%
5. Surface finish: Immersion Gold
6. Backdrilling process for stub reduction
7. Strict layer registration, low warpage, IPC Class 2

Production Difficulties & Process Breakthrough

1. Layer misalignment & lamination warpage (primary low-yield cause) Optimized prepreg stacking structure, adopted multi-stage heating-pressure lamination curve. Pre-bake core boards to release internal stress. Board warpage greatly reduced.
2. High precision impedance & low signal loss Stackup simulation before production, tightly control dielectric thickness and copper profile. Optimize etching process for vertical copper sidewall to minimize insertion loss.
3. Backdrilling depth control risk Improved drilling positioning & depth monitoring, reduce residual stub length, avoid signal reflection.
4. Shorten lead time without quality compromise Prioritized DFM review, parallel inner layer exposure and AOI inspection to cut waiting time.

Project Outcome

• Production yield improved from 82% to above 95%
• Lead time reduced by 30%
• 100% passed electrical test, AOI, impedance and insertion loss test
• Stable high-speed signal transmission performance for 400G optical module

Customer Feedback

Customer highly recognized JQPCB’s high-speed PCB manufacturing capability. Improved yield and shortened cycle stabilized their mass production plan, both parties established long-term strategic cooperation.