PCB is a printed circuit board which is formed on the basis of the general purpose material, which has been widely used in various electronic circuit components. Surface treatment can ensure that the printed circuit board in the subsequent assembly and use of solderability. Surface treatment process in addition to meet the basic requirements of welding and bonding strength, but also need to meet the customer's special requirements for the product, such as appearance, color, corrosion resistance, oxidation resistance, etc..
With the continuous development of PCB printed circuit board technology, the requirements of the line width and line spacing of the printed circuit board (PCB) are gradually improved. With the gradual rise of the surface mount technology of printed circuit board, the connection plate and the pad of the printed circuit board are required to have good flatness and flatness.
In order to meet the requirements of the development of SMT, the manufacturers are constantly improving and improving the printed circuit board surface treatment technology, including the gold plating technology. The gold layer has the characteristics of corrosion resistance, high conductivity, good weldability, low and stable contact resistance, high temperature resistance, soft and abrasion resistance. At the same time, gold and other metals (such as Co, Ni, Fe, In, Cd, Ag, Cu, Sd, Pd, etc.) are easy to alloy, the hardness of the alloy is higher and the wear resistance is better.
But with the rise in the price of gold, gold has become a focus on the cost of the project. This paper mainly through the optimization of process parameters, control gold plating layer thickness uniformity and control, improve the gold drop time, reduce our salt consumption, saving the cost of gold.
Save the salt solution in the process of gold plating
Analysis of salt consumption in the process of gold plating
The salt consumption mainly includes the gold plating of printed circuit board drawing gold layer bath with consumption and consumption of two aspects. The gold layer is too thick or the bath with excessive amount of salt will cause the waste of invalid salt consumption costs.
Gold plating thickness control
At present, the thickness of the gold plating layer is mainly controlled by the requirements of the production production instructions. In view of this situation, the development of internal gold plating thickness control standards. Signed by the relevant departments to control the thickness of the internal contact sheet thickness, without affecting the quality of the production board under the premise of the equipment and technical capabilities within the scope of the thickness of the gold plating on the effective control. According to the Guangzhou factory, "gold plating thickness control detailed management of internal contact sheet", combined with the characteristics of the Zhuhai factory products, the contents of the internal contact list to modify and improve, re signed execution.
Process parameter control
1 potion stability control
The stability of the liquid is the decisive factor affecting the reaction rate. As the main consumption of gold and gold ion reactive components, its concentration will increase production and consumption fluctuation, the salt concentration fluctuations would in turn lead to gold reaction rate fluctuations. Therefore, in order to ensure the gold reaction rate stability, we must make the concentration of salt in the gold bath maintained at a relatively stable level. In the premise of stability, the setting and adjustment of gold plating parameters will be more accurate, the thickness of the gold plating layer will have a more stable control. In order to maintain the stability of the salt concentration of gold in the cell, must pay attention to the following two points:
(1) maintain the accuracy and completeness of production records;
(2) to keep the salt supplement timely, follow a few times "principle.
Normalization of 2 parameter control
In parts and batch production and batch of PCB board with gold plated layer thickness and adding process control production needs, improve the specific requirements as shown in table 1.
Method of reducing salt consumption in the process of PCB circuit board plating
3 gold plating thickness monitoring measures
To ensure the monitoring effect, the following monitoring measures are hereby formulated.
(1) making "gold cost saving projects" for monitoring the thickness of gold plating control content, making "gold cost saving project monitoring table" of production records, completeness, timeliness, the addition of gold plating layer thickness control, batch control and plate thickness of gold to add salt after parameter adjustment project inspection, and for the nonconformity analysis and improvement.
(2) ERP plating layer thickness data derived in the ERP system to improve the current gold consumption data, some is incorrect and incomplete. To the information center to submit software requirements, to improve the module, ensure the accuracy and integrity of the salt consumption data.
(3) statistical analysis of gold plating thickness data
Every week, the thickness of the ERP gold plating layer was recorded, according to the line and the thickness of the gold plating layer, the performance and stability of the gold plating layer thickness control were analyzed.
Optimization of gold plating uniformity
If the uniformity of gold plating is low, the control of the thickness of gold plating layer is seriously affected. In the production process, in order to meet customer requirements the minimum thickness of gold, often the gold plating layer is thick, resulting in a serious waste of gold salt. In order to optimize the plating thickness uniformity of groove, can begin to improve from the change of anode titanium mesh setting mode and position, to find the best solution through technical testing. At the same time, in the process of gold plating for relatively small production board, can be equipped with anode baffle production, can also significantly improve the uniformity of gold plating.
Reduce the amount of liquid outlet
If the grasp of time has a greater deviation, the lack of time will result in a large amount of liquid out of the tank, and the water is too long and will reduce production efficiency and waste of production capacity.
At the same time, if the vibration device is added, the slot liquid attached to the surface of the plate can be dripped faster under the action of external force, and the volume of the liquid outlet can be effectively reduced