Gold price are premium， alternatives to Gold Plating in Ceramic PCBs

In recent years, the gold price motivated by the market trend risen continuously. By 11:00 a.m.ET, gold surged 2.6% to about $3,377 per ounce. Which has been up to the highest since May (mining.com).  JP Morgan made a gold price furture perdiction that the price will go up to $4,000/oz in the second quarter of the next year. As a result of its outstanding importance of the electrical properties of materials, it has spread incredible of industries, especially in the ceramic PCB industry.  Hence, the problem of how to use gold more efficiently and economically has become significant for buyers.

In the current stage, plenty of technologies are related to gold plating. To ensure the deposit performance, save on the cost of gold. There are measures to reduce the consumption of gold.

To reduce the thickness of the deposit

Gold as a component applied to electronic surface technology can be applied in four ways. Electroplating, thermal effects, thick film technology, and thin film technology. Among these technologies, the consumption of gold electroplating occupied the largest account. The uneven distribution of the electric field during the electroplating process often leads to the tip effect, resulting in non-uniform coating thickness.  This not only affects product quality but also causes significant gold wastage.  To address this issue, the following improvements are necessary:

Electroplating

• •   Anode Distribution Optimization

By analyzing the influence of an electric charge distribution, we have restructured the placement of anodes to reduce the surface area in regions with high

 intensity. This adjustment enables a more uniform distribution of electric field lines, improving plating uniformity and significantly reducing gold utilization.

• • Fixture (Jig) Optimization

To address the current concentration at high points that exacerbates the tip effect, we developed a new electroplating jig design and improve ability of gold tarnish resistance. This innovative fixture evenly distributes the current across the component surface and effectively suppresses the tip effect by up to 80%. As a result, plating uniformity has improved dramatically, contributing to a notable reduction in production costs.

Thick Film Processing improvement

Gold consumption in ceramic thick film technology is substantial, particularly with typical gold layer thicknesses around 10 μm (400 microinches). The rising price of gold has led to soaring production costs. However, through our process optimization, we have achieved a 10% expense reduction without compromising product quality. Key measures include:

• • Use of finer mesh

By increasing the mesh count of the printing screen, we are able to control the gold plating layer thickness more precisely. Our tests show that a gold thickness of approximately 2 μm (80 micro inches) is sufficient to ensure reliable gold wire bonding pads, with a peel strength exceeding 5 kgf. This level of performance meets industrial product standards. Moreover, reducing gold layer thickness lowers capacitive parasitics between circuit lines, which is particularly advantageous for high-end electromagnetic applications.

• • Selective Gold Printing

We further reduced gold usage by printing gold paste only on functional areas, such as gold wire bonding on bonding pads, while less critical circuit areas are printed using silver paste. This selective metallization approach allows us to achieve the same product functionality with significantly less gold.

Thin Film Process Optimization

Conventional Deposition Challenges

In conventional thin film processes, Au layer thickness typically ranges from 1–3 μm (40–120 μin). Current methods, such as evaporation or sputtering, are time-consuming and result in significant material loss. A large portion of the gold fails to deposit on the product and instead accumulates on the chamber fixtures or shielding arms, leading to considerable wastage. Additionally, gold is often deposited on non-functional areas of the substrate, further increasing unnecessary consumption.

Selective Electroplating Advantage

Our company has developed an optimized evaporation + selective electroplating process. In this method, a thin gold seed layer of 0.1–0.2 μm (4–8 μin) is first deposited via evaporation, followed by photolithography and a selective gold electroplating technique to increase the thickness only on the required functional areas. This approach significantly reduces gold waste and lowers overall production costs in the thin film process.

Some functions can be done to replace gold plating

Alternative Surface Finishes for Ceramic Substrates

Palladium and Gold Combination

Pure palladium or palladium nickel plating can become components of substrates instead of plating gold. Based on this, adding a film of gold, generally, up from 2 to 5µm, in some specific areas like contact application, this combination performs better than hard gold(Gold Plating).  

Tin (Sn) as a Gold Plating Substitute

Sn(Tin) is regarded as of substitute for gold plating. With remarkable soldering capability, high electrical conductivity, a low-temperature melting point, and excellent corrosion resistance. But its drawback is obvious. The surface of Sn-plated whisper growth speed influences the lifecycle of electronic components.

Alloying Solutions for Whisker Mitigation

To address this issue, alloying Sn and Pb to delay the increase of whisper, via restructuring the columnar grain, which could prevent the diffusion of elements in the deposit.

Organic Solderability Preservative (OSP）

Oxidation Protection and Performance

Organic Solderability Preservative(OSP) is a way to prevent oxygen and expose brilliant thermal resistance and solderability. Research indicated that it remains stable at high temperatures, even better than lead-free solders.

Process Characteristics

Any OSP craft needs to be maintained and controlled. But OSP is still a costly and simple method among all surface processes, which requires low equipment to maintain and consumes less energy in the equipment.

Compatibility and Applications

It is also proven that it has good adaptation and matches with SELECTIVE ENIG process. There is no need to heat can combine with tin-lead solder.

Cu–Sn Alloy and Its Role in Soldering

Material Characteristics

Cu–Sn is a non-ferrous metal alloy that is flexible, conducts heat well, and corrosion resistant effectively. Cost is a key element to be considered.

Cost Considerations

The majority of lead-free solders account for a higher cost than Sn–Pb solders, about 1.3 times( Recent advances on Sn–Cu solders with alloying elements: review). The notable metals are blamed for this, like gold and silver.

Comparison with Other Alloys

Compared with Sn-Pb, Sn-Pb has become a kind of product that the public uses frequently. However, the metrics of Sn -Cu hold less mechanical properties and wettability than Sn-Ag. Adding Au will solve this problem. Additionally, integrating Ni and Sb at a certain proportion decreases the melting point and preserves the reliability of solder joints ( Mater Sci: Mater Electron). employing different elements to approach a specific situation.

conclusion

As gold prices surge, reducing its use in electronic finishes becomes essential.  Effective strategies include minimizing deposit thickness and exploring alternative surface finishes.  Materials like Sn-Pb, Sn-Cu, OSP, and Pd-Ni alloys offer excellent solderability, corrosion proof, and thermal stability, making them suitable  substitutes in laser etching,  printing techniques, join between pieces of materials, cutting board.  While some trade-offs exist, such as whisker growth or reduced durability, these can be mitigated through micro-alloying or multi-material bonding layer design.  With proper process control and material selection, manufacturers can achieve a balance between performance, reliability, and cost-efficiency, paving the way for sustainable production without sacrificing quality.