A large number of quality problems related to the etching surface are focused on the etched part of the upper surface. These problems arise from the impact of the etching agent produced by the colloidal laminate. It is important to note that colloidal laminates accumulate on the surface of the copper. On one hand, this accumulation affects the injection force; on the other hand, it blocks the supplement of fresh etching solution, thereby reducing the etching speed. Due to the formation and accumulation of colloidal laminate, the etching degree of the upper and lower graphics of the substrate differs. The substrate that enters first is not yet fully formed due to accumulation, resulting in faster etching, which can cause over-etching or corrosion. Substrates entering later encounter already formed accumulation, slowing down the etching speed.
**Problems to be aware of in the PCB etching process**
The most critical factor in maintaining etching equipment is to ensure high cleanliness and no blockage of the nozzle, allowing for smooth spraying. Blockage or slagging can cause pressure issues during injection, impacting the plate surface. If the nozzle is not clean, uneven etching may occur, potentially ruining the entire circuit board.
Maintenance of the equipment involves replacing damaged and worn parts, including the nozzle, which is subject to wear. Additionally, it is crucial to prevent slagging in the etching machine, as excessive accumulation can disturb the chemical balance of the etching solution. Chemical imbalance can exacerbate slagging. Sudden excessive slagging in the etching solution often signals an issue with the solution balance. At such times, appropriate cleaning or solution supplementation with strong hydrochloric acid is recommended.
Side erosion can result in edge bursting. Generally, the longer the printed board remains in the etching solution, the more pronounced the side erosion becomes. This erosion significantly affects the precision of printed wires, and severe side erosion can prevent the creation of fine wires. Reduced side etching and abrupt edges increase the etching coefficient, which, when high, helps maintain thin wires close to their original size.
Excessive edge protrusion, whether due to tin-lead alloy, tin, tin-nickel alloy, or nickel plating etching agents, can cause conductor short-circuiting. Protrusions are prone to tearing down, creating electrical disconnections between wire points.
Several factors contribute to lateral erosion, summarized as follows:
– Soak and bubble etching contribute to greater side erosion, while splash and spray etching lead to less side erosion, with spray etching having the best effect.
– Different etching solutions have varying chemical compositions, etching rates, and etching coefficients. For instance, acidic copper chloride etching solution typically has an etching coefficient of around 3, whereas alkaline copper chloride can reach 4.
– A slower etching rate leads to more severe side etching.
– Improving etching quality is closely related to accelerating the etching rate. Faster etching reduces the time the substrate is exposed to the etching solution, resulting in less side etching and clearer, tidier figures.
– Higher pH values in alkaline etching solutions increase side erosion, with pH generally needing to be controlled below 8.5 to minimize side erosion.
– Low-density alkaline etching solutions aggravate side erosion, while high copper concentration solutions are advantageous for reducing side erosion.
– To minimize side etching of thin wires, ultra-thin copper foil is recommended. Thinner copper foil reduces the exposure time in the etching solution, thereby reducing side erosion.
**Problems to be aware of in the PCB etching process**
The most critical factor in maintaining etching equipment is to ensure high cleanliness and no blockage of the nozzle, allowing for smooth spraying. Blockage or slagging can cause pressure issues during injection, impacting the plate surface. If the nozzle is not clean, uneven etching may occur, potentially ruining the entire circuit board.
Maintenance of the equipment involves replacing damaged and worn parts, including the nozzle, which is subject to wear. Additionally, it is crucial to prevent slagging in the etching machine, as excessive accumulation can disturb the chemical balance of the etching solution. Chemical imbalance can exacerbate slagging. Sudden excessive slagging in the etching solution often signals an issue with the solution balance. At such times, appropriate cleaning or solution supplementation with strong hydrochloric acid is recommended.
Side erosion can result in edge bursting. Generally, the longer the printed board remains in the etching solution, the more pronounced the side erosion becomes. This erosion significantly affects the precision of printed wires, and severe side erosion can prevent the creation of fine wires. Reduced side etching and abrupt edges increase the etching coefficient, which, when high, helps maintain thin wires close to their original size.
Excessive edge protrusion, whether due to tin-lead alloy, tin, tin-nickel alloy, or nickel plating etching agents, can cause conductor short-circuiting. Protrusions are prone to tearing down, creating electrical disconnections between wire points.
Several factors contribute to lateral erosion, summarized as follows:
– Soak and bubble etching contribute to greater side erosion, while splash and spray etching lead to less side erosion, with spray etching having the best effect.
– Different etching solutions have varying chemical compositions, etching rates, and etching coefficients. For instance, acidic copper chloride etching solution typically has an etching coefficient of around 3, whereas alkaline copper chloride can reach 4.
– A slower etching rate leads to more severe side etching.
– Improving etching quality is closely related to accelerating the etching rate. Faster etching reduces the time the substrate is exposed to the etching solution, resulting in less side etching and clearer, tidier figures.
– Higher pH values in alkaline etching solutions increase side erosion, with pH generally needing to be controlled below 8.5 to minimize side erosion.
– Low-density alkaline etching solutions aggravate side erosion, while high copper concentration solutions are advantageous for reducing side erosion.
– To minimize side etching of thin wires, ultra-thin copper foil is recommended. Thinner copper foil reduces the exposure time in the etching solution, thereby reducing side erosion.
