Gallery View: Higher layer count complements reliability priority in multilayer PCBs

Makers of multilayer PCBs in mainland China target production of types with up to 20 layers or above to meet upgrades in applications.

Multilayer PCB manufacturers in mainland China are eyeing the release of units with layer counts of 20 or more to match higher requirements in the automotive, communications, robotics and computer sectors. This is while keeping product reliability the key goal.

A 22-layer FR-4 board, the SS19005 model introduced by Sunshine Global Circuits Co. Ltd has 1oz copper on the ground and power planes, as small as 0.45mm drilled holes, and 3.4 and 4.7mil minimum line width and spacing. The unit with controlled impedance uses resin on all via holes, immersion gold surface finish and matte blue solder mask. It complies with RoHS and REACH standards.

HDI and rigid-flex variants remain hot in the line, specifically the former with blind and buried microvias. HDI PCBs suit 5G devices.

The mainstream selections of local makers include rigid, rigid-flex and flexible types, which are based on materials such as FR-4 and its halogen-free variant, polyimide, CEM-1, CEM-3, Tg, high-Tg and Rogers. The boards come in four to 12-layer models. Those with up to eight layers currently take up the majority of shipments.

In minimum terms, the PCBs have 3mil line width and spacing, 0.2mm holes and 0.15mm-thick inner layers, while copper thickness ranges from 0.5 to 7oz. These can have a HAL, gold- or tin-plated, or immersion gold, silver or tin surface finish. Board dimensions can be up to 580x900mm and thickness 0.21 to 7mm. Most makers ensure products conform to RoHS and REACH.

All key materials are usually sourced from the local market. Companies turn to foreign providers only as required. Copper-clad laminates take up between 20 and 40 percent of total outlay and their cost depends on that of copper. Suppliers will adjust PCB prices if input expenditure increases.

The products in this gallery have been handpicked by our mainland China-based market analyst for representing current trends in multilayer PCBs from greater China makers.

2 to 16 layers, FR-4 base

The MultilayerPCB-1 model from Finenet Electronic Circuit Ltd has an FR-4 base and ENIG surface finish, and can be made with two to 16 layers. At minimum, the unit has 4mil line width and spacing, 5mil inner layer clearance, 3mil dielectric thickness, and 0.254mm drilling and 0.2mm finished hole sizes. The overall finished board thickness is 0.4 to 4mm.

The order quantity is negotiable. Delivery is within 7 days.

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2, 8, 10 layers, FR-4 base

Finenet Electronic Circuit Ltd's MultilayerPCB-2 model stacks up eight, 10 or 12 layers, and uses an FR-4 base with HASL, lead-free HAL, flash gold, immersion gold or silver, or OSP surface finish. It has 4mil minimum line width and spacing, 5mil minimum inner layer clearance, 3mil minimum dielectric thickness, and 0.254mm minimum drilling and 0.2mm minimum finished holes. The overall finished board thickness is 0.4 to 4mm.

The negotiable order quantity has a delivery lead time of 7 days.

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6 layers, 53x57x1.6mm

Model 221904-190207 6-layer PCB from Full Years Technology Co. Ltd has 1oz copper and measures 53x57x1.6mm. The unit adopts an Isola I-Tera MT40 laminate material and iPI impedance controller. It has blind vias on L1 to L4, with laser routing stopping on L3 and L5.

The maker requires a minimum order of 100 units. Delivery lead time is 7 days.

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4 layers, immersion gold

From Full Years Technology Co. Ltd, the model PCB-M13 4-layer PCB has 1mil polyimide top and 1mil polyimide bottom overlays, 1oz copper, immersion gold surface finish and white legend. The RoHS-compliant unit uses 3M adhesive transfer tape 467MP.

The order quantity is negotiable. Delivery takes 7 days.

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20 layers, Tg170 FR-4 base

Golden Circuits Technology Co. Ltd offers this 20-layer PCB, Mcpcb01-20layers model, adopting a Tg170 FR-4 base, 1oz inner and 2oz outer copper, and 3µin immersion gold surface finish. The unit with resin plug holes has 3mil minimum line width and spacing, 12 controlled impedance groups, ±10 percent controlled impedance tolerance, and 1mm laser-drilled blind and buried vias.

The negotiable order quantity has a 5-day delivery lead time.

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10 layers, Tg170 FR-4 base

This multilayer PCB with 10 layers and a Tg170 FR-4 base from Golden Circuits Technology Co. Ltd, Mcpcb01-10layers model, uses 1oz inner and 2oz outer copper, and 3µin immersion gold surface finish. The unit with 3mil minimum width and spacing, 1mm laser-drilled blind and buried vias, and resin plug holes has ±10 percent controlled impedance tolerance.

The order quantity is negotiable. Delivery takes 5 days.

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