2-Layer RO4350B LoPro PCB built on 4mil substrate with Immersion Gold Finish for RF, microwave, high-speed digital app

2-Layer RO4350B LoPro PCB | 4mil Core | Immersion Gold Finish

Product Overview

We are pleased to present this newly customized 2-layer rigid PCB built on Rogers RO4350B LoPro® high-frequency laminate. Engineered for demanding RF, microwave, and high-speed digital applications, this board delivers exceptional signal integrity with low conductor loss, thanks to Rogers' proprietary reverse-treated foil (LoPro®) technology.

The board measures 78mm x 101mm (single piece) with an ultra-thin finished thickness of just 0.2mm (including 4mil core + 2 x 35μm copper). Minimum trace and space are 5/6 mils, with a minimum finished hole size of 0.25mm. No blind vias are used in this construction.

This design features a blue top solder mask for circuit protection and white top silkscreen for component identification. The bottom side has no solder mask and no silkscreen, optimizing RF performance where needed. The Immersion Gold surface finish provides excellent solderability, flatness for fine-pitch components, and superior corrosion resistance. Every board undergoes 100% electrical testing prior to shipment and conforms to IPC-Class-2 quality standards. Gerber files are supplied in RS-274-X format, and worldwide shipping is available.

PCB General Specifications

Material Advantages: RO4350B LoPro®

The RO4350B LoPro® laminate from Rogers Corporation uses a proprietary technology that allows reverse-treated foil (LoPro®) to bond to standard RO4350B dielectric. This results in a laminate with low conductor loss for improved insertion loss and signal integrity while maintaining all other desirable attributes of the standard RO4350B laminate system.

RO4350B is a hydrocarbon ceramic laminate designed to offer superior high-frequency performance and low-cost circuit fabrication. Unlike PTFE-based high-performance materials, RO4000 series laminates do not require specialized via preparation processes such as sodium etch. This material is a rigid, thermoset laminate that can be processed using standard epoxy/glass (FR-4) circuit board processing techniques and is capable of being handled by automated systems.

The thermal coefficient of expansion (CTE) of RO4350B is similar to that of copper, providing excellent dimensional stability—a critical property for mixed-dielectric multilayer board constructions. The low Z-axis CTE ensures reliable plated through-hole quality, even in severe thermal shock applications. With a Tg exceeding 280°C, the expansion characteristics remain stable over the entire range of circuit processing temperatures, including lead-free soldering.

RO4350B LoPro® Material Properties

PCB Stackup & Construction

The board features an ultra-thin 2-layer stackup:

Top Copper (Layer 1): 1 oz (35μm) – LoPro® reverse-treated foil

Dielectric Core: Rogers RO4350B LoPro® – 4mil (0.102mm)

Bottom Copper (Layer 2): 1 oz (35μm) – LoPro® reverse-treated foil

Total Finished Thickness: 0.2mm

Minimum trace and space are 5/6 mils, with a minimum finished hole size of 0.25mm. Via plating thickness is 20μm, and no blind vias are used. The design supports 24 components, 49 total pads (31 thru-hole, 18 top SMT), 26 vias, and 2 nets.

The blue top solder mask provides circuit protection and insulation, while the white silkscreen enables clear component identification. The bottom side remains unmasked and without silkscreen, which may be beneficial for specific RF grounding or thermal requirements.

Typical Applications

Cellular base station antennas and power amplifiers

Digital applications such as servers, routers, and high-speed backplanes

LNB's (Low Noise Block downconverters) for direct broadcast satellites

RF identification tags (RFID)

High-frequency designs operating beyond 40 GHz

Low-PIM applications for base station antennas

Multilayer PCB constructions requiring mixed dielectrics

All PCBs are 100% electrically tested and shipped with a Certificate of Conformance per IPC-6012. For Gerber review, stackup confirmation, or volume pricing, please contact our technical sales team.