Sunkey Electronics Successfully Develops 16‑Layer 5‑StepHigh‑Frequency PCB

1. Preface

High‑frequency PCB refer to special circuit boards operating at high electromagnetic frequencies. With low dielectric constant (Dk) and low dielectric loss (Df), they are PCBs applied in high‑frequency (frequency above 300 MHz or wavelength less than 1 m) and microwave (frequency above 3 GHz or wavelength less than 0.1 m) fields. They are widely used in automotive anti‑collision systems, satellite systems, radio systems and other fields.

2. Overview of 16‑Layer 5‑Step High‑Frequency Product

High‑frequency HDI boards feature high processing difficulty and strict impedance requirements. In particular, dimensional expansion‑shrinkage caused by multiple lamination of core boards with different thicknesses, delamination and board blistering induced by ultra‑high Tg value, as well as hole roughness from drilling are critical factors determining product yield. These factors are closely related to the blind‑via design, stack‑up structure and circuit layout of the PCB.

3. Product Information

(See Figure 1)

4. Product Process Flow Design

4.1Blind‑via Structure

1-2 1-6 3-4 9-10 11-14 1-10 1-14，Among them, the 1.35 mm‑thick Rogers core board for Layer 15‑16 requires self‑lamination。

4.2 Lamination Structure (See Figure 2):

4.3 Number of Lamination Cycles (See Figure 3):

Note: A total of 5 lamination cycles are required, all adopting counter‑lamination structure.

5.Key Control Points

5.1 Lamination Compression Factor:

The inner core boards shall undergo five times of resin grinding and multiple electroplating. Pre‑set compression factors are required before each lamination cycle

Lamination Effect Diagram (See Figure 4: Laminated Concentric Circles)。

Figure 4

5.2 Lamination

The high‑frequency board undergoes 5 lamination cycles. It is necessary to prevent board blistering and delamination, optimize the internal copper‑layer design and lamination stack‑up, and adopt dedicated parameters and a small‑size silicone‑press laminator for fabrication.

5.3 Drilling

The aspect ratio is 12.8:1. Phenolic cover sheets are adopted for drilling. Brand‑new 0.4 mm UC drill bits are used with spindle speed of 110 Kr/min, and burrs are removed by manual grinding.

5.4 Outer‑layer Etching

Single‑ended impedance tolerance: ±3 Ω. Five‑point impedance testing shall be performed after lamination of the main card. Precise regional copper reduction and dynamic compensation for outer‑layer circuits are applied, with vacuum acidic etching adopted.

Summary:

Sunkey Electronics is a new high‑tech enterprise dedicated to the R&D and manufacturing of high‑end quick‑turn prototypes and small‑batch PCBs. The company’s mission is to advance toward the cutting‑edge of electronic technology and push the limits of circuit technology. Its product portfolio covers high‑frequency, high‑speed, high‑layer‑count boards, as well as semiconductor testing, burn‑in testing, and 5G communication optical modules.