8-Layer HDI PCB Built On Tg175°C FR-4 Immersion Gold PCB for Satellite Radio Applications

Printed Circuit Boards are custom-made products; the images and specifications provided are for reference only.

1.1 General description

This 8-layer HDI printed circuit board is engineered for high-frequency applications such as satellite radio systems, constructed on high-performance FR-4 Tg175℃ substrate from ITEQ Taiwan. With a 1.6mm thickness and advanced HDI structures—including blind vias from top layer to inner 2 and buried vias from inner 2 to inner 4—it ensures reliable signal integrity and interconnection density. Featuring immersion gold surface finish on pads, Taiyo green solder mask, and white silkscreen, each 1-up panel is manufactured to IPC 6012 Class 2 standards using supplied Gerber data and shipped in batches of 25 panels, providing an ideal solution for demanding RF and telecommunications designs.

1.2 Features and benefits

1. High Tg Materials are RoHS compliant and suitable for high thermal reliability needs;

2. Immersin gold has high solderability, no stressing of circuit boards and less contamination of PCB surface;

3. Delivery on time. Higher than 98% on-time-delivery rate;

4. 30000㎡ output capability per month;

5. More than 18 years of experience;

6. Powerful PCB capabilities support your research and development, sales and marketing;

7. Any Layer HDI PCBs;

8. International approvals;

Appendix: Data sheet of DiClad 870

1.4 Applications

WiFi Range Extender

CCTV System

Satellite Communication

5G Speed

Router WiFi 4G

Solar Panel Inverter

GPS Tracking Systems

Embedded Processor

PLC Programs

Phone systems

1.5 Glass Transition Temperature (Tg)  

The thermal properties of the resin system are characterized by the glass transition temperature (Tg), which is always expressed in °C. The most critical property is thermal expansion. When measuring expansion versus temperature, a characteristic curve is obtained as shown in the following figure. The Tg is determined by the intersection point of the tangents to the flat and steep sections of the expansion curve. Below the glass transition temperature, the epoxy resin remains rigid and glass-like. When the glass transition temperature is exceeded, it transitions into a soft, rubbery state.

For the most commonly used types of epoxy resin (FR-4 grade), the glass transition temperature ranges from 115-130°C. During soldering processes, the board easily exceeds this glass transition temperature. The board expands in the Z-axis direction, creating stress on the copper plating of the hole walls. When the temperature exceeds Tg, the expansion rate of epoxy resin is approximately 15 to 20 times greater than that of copper. This creates a potential risk of cracking in the plated through-hole walls, with the risk increasing proportionally with the amount of resin surrounding the hole wall. Below the glass transition temperature, the expansion ratio between epoxy resin and copper is only about three times, making the risk of cracking negligible in this temperature range.

The Tg of standard boards is typically above 130°C, while medium Tg is generally above 150°C, and high Tg is typically above 170°C. PCB boards with Tg ≥ 170°C are commonly referred to as high Tg PCBs.

1.6 Manufacturing Process of Multi-layer PTH PCB (via filled)

(1). Material Shearing

(2). Inner Layer Dry Film

(3). Inner Layer Etching

(4). AOI 1  

(5). Black Oxidation

(6). Milling Outline Frame

(7). Inner Layer Drilling

(8). PTH 1

(9). Inner Layer Dry Film

(10). Pattern Plating 1

(11). Via filled

(12). Outer Layer Drilling

(13). PTH 2

(14). Pattern Plating 2

(15). Outer Layer Dry Film

(16). Copper-tin Electro-Plating

(17). Peeling and Etching

(18). AOI 2

(19). Solder Mask

(20). Silkscreen Printing

(21). Surface Finishing

(22). Electrical Testing

(23). Prolie Contouring

(24). FQC

(25). Packaging

(26). Delivery