Analysis of nickel palladium plating process for HTCC packaging tube shell

HTCC packaging shells account for over 60% of the market share in the field of electronic packaging, mainly used in packaging for optical communication, image sensors, red ultraviolet sensors, power devices, solid-state relays, microwave devices, power supplies, optocouplers, etc. HTCC ceramic multilayer substrates are also widely used in high reliability microelectronic integrated circuits, high-power micro assembly circuits, vehicle mounted high-power circuits, and other fields. The nickel palladium plating process for HTCC packaging tube shell plays a crucial role as a key process and technique.

Function Description:

HTCC ceramic shell nickel palladium plating refers to depositing a layer of nickel, palladium, and gold on the surface of HTCC electronic components coated with tungsten through chemical plating. Nickel as the bottom layer provides good corrosion resistance and adhesion, palladium as the intermediate layer prevents corrosion of nickel during gold deposition, and gold as the surface layer provides excellent conductivity and weldability while preventing oxidation.

Process flow description:

Pre treatment degreasing (using alkaline degreaser or organic solvent to remove surface oil and impurities) → water washing → acid washing (further cleaning the surface with acidic solution) → water washing → micro etching (lightly etching the tungsten surface, increasing surface roughness, and providing adhesion to the electroless nickel plating layer) → water washing → palladium activation (immersing in palladium salt, increasing the catalytic active sites of electroless nickel plating, triggering the electroless plating reaction) → water washing → electroless nickel plating (forming a uniform and dense electroless nickel plating layer, providing mechanical strength and conductivity) → water washing → electroless palladium plating (depositing a uniform palladium metal layer on the surface of the nickel layer to prevent nickel oxidation, while forming good adhesion with the electroless gold plating layer) → water washing → electroless gold plating (forming an extremely thin gold layer on the surface, providing Good conductivity, oxidation resistance, and weldability) → water washing → drying.

Key control points:

1. Stability of plating solution

During the electroplating process, the concentrations of main salts (nickel ions, palladium ions, gold ions), reducing agents, and chelating agents in the plating solution are regularly analyzed. Nickel ions can be monitored in real-time by colorimetric method, while palladium ions and gold ions can be monitored in real-time by XRF method. Main salts are automatically added by comparison, and reducing agents, chelating agents, and other additives are added in proportion to ensure consistency between the concentrations of main salts and additives in the solution.

The stability of pH affects the deposition rate and coating quality. Automatic analysis and addition equipment can monitor the pH of the solution in real time and perform replenishment to maintain the stability of the solution pH.

2. Temperature uniformity

Excessive or insufficient temperature can affect the deposition rate and dissolution of the chemical plating reaction. The chemical plating tank adopts a fully enclosed heating/cooling interlayer, which evenly transfers heat through circulating water to avoid temperature gradients caused by one-sided heating. The tank body is treated with mirror stainless steel or stainless steel sprayed with PTFE to ensure efficient and uniform heat conduction.

Configure a circulating filtration pump and stirring device to force convection of the solution in the tank and achieve uniform temperature distribution.

Using a PID temperature controller, the heating power is automatically adjusted based on real-time temperature data to maintain temperature stability.

3. Time consistency

Insufficient or excessive plating time may lead to uneven coating, local defects, and increased costs. The automatic production line controlled by PC+PLC can trigger timing when the workpiece enters the slot, and automatically lift it after reaching the set time. The rate of each seat and lift is consistent to avoid manual operation errors.

Hengli Company has many years of experience in designing and manufacturing HTCC shell plating production lines. Through independently developed automation and control systems, automatic analysis and dosing systems, MES+SCADA systems, while ensuring efficient production, the quality and consistency of the coating can also be guaranteed; Simultaneously balancing environmental protection and clean production to support the sustainable development of enterprises.

Automation and control system: Through a flexible automation control system, multiple process routes can be preset, and product batches and processes can be automatically identified by scanning codes, and process routes can be automatically selected. The loading and unloading of workpieces, as well as automated transportation, can also achieve mechanized operations, improving production efficiency and quality stability. By utilizing advanced sensors and intelligent control systems, precise control of production line parameters can be achieved.

Automatic analysis and dosing system: using titration, colorimetric, conductivity, specific gravity and other analysis methods, combined with intelligent analysis calculation programs and central control automatic dosing system, to achieve functions such as automatic sampling, online analysis, automatic dosing, and automatic maintenance of plating solution.

MES+SCADA system: integrated process parameter preset, real-time data monitoring (tank concentration, temperature, liquid level), and abnormal alarm function; Through IoT technology, product process data is stored and organized, packaged with product batch and post inspection data, and uploaded to the cloud or enterprise management system for remote monitoring and data analysis, helping enterprises optimize production and make decisions.

Environmental treatment system: Hengli Company's patented online recycling equipment, resource recovery equipment, and environmental zero emission system can achieve the recycling and reuse of precious metals in tank and washing water, reduce the consumption of raw materials, and decrease the amount of washing water used, reducing the operating costs of enterprises. The environmental zero emission system realizes the recycling of water resources, turns "waste" into treasure, and adapts to the increasingly strict trend of environmental supervision.