Solder resists and cover sheeting

Opening of solder resists

Laser processing presents itself for the most demanding solder resists in the HDI area <50 μm. The laser ablates the solder resist in the area of the openings and cleans the metal layer. A residue-free copper surface remains.

Laser processing facilitates production of openings starting at 30 μm in diameter. By means of vision systems, laser systems correct positional errors even during processing. This process guarantees a maximum of positioning accuracy and throughput.

Printed circuits generally have to be provided with solder resists to improve mechanized soldering. The cover masks that are usually attached in screen printing or by photo technology help prevent solder bridges and thus short circuits.

Opening of cover foils on copper-clad base material

The laser ablates the sheeting material in the area of the desired openings after it was applied on the printed board. The fineness and precision of the laser beam creates ultra-fine openings with high positional accuracy. In addition, with small quantities costs for the stamping or punching tool can be saved.

Cover sheeting on flexible or rigid printed boards seals the conductor tracks against corrosive environmental influences and at the same time serves as a solder resist.

Cover sheeting is film coated on one side with adhesive, e.g., on a polyimide base. Soldering surfaces or pads that are to remain open are mechanically processed before the coating, i.e., they are drilled or punched out. Ultra-fine openings in the cover sheeting cannot be mechanically implemented. However, this task is no problem for the laser systems of LaserMicronics GmbH.

Advantages of laser processing

• Ultra-fine openings in the HDI area <50 μm in the solder resist possible
• Ultra-fine openings in cover sheeting, e.g., polyimide
• Residue-free copper surface
• No film or screen creation, direct CAD data conversion
• Automatic recording via corner marks
• Automatic correction of deformations and position through online scaling
• High level of precision and positional accuracy for the openings
• No tool costs
• Higher accuracy of processing on the material than with conventional cutting of sheeting
• Quick change of cut pattern directly from layout data