HASL (Eutectic; 63 percent Tin to 37 percent Pb)
▪ Usual coating thickness is 0.8 µm (0.000003 in) to 5 µm (0.0002 in); dependent upon the design
▪ Very good ability for soldering
▪ 0.635 mm (0.025 in) surface mount pitch or greater ability
▪ 0.75mm (0.030 in) is the minimum board thickness ability
▪ Adequate shelf life
High Tg refers to high heat resistance.Generally, the boards of Tg are over 130 degrees, high Tg is generally greater than 170 degrees, and medium Tg is about greater than 150 degrees. Generally, PCB printed boards with Tg≥170℃ are called high Tg printed boards.
With the rapid development of the electronic industry, especially the electronic products represented by the computer, towards the development of high function and high multi-layer, the higher heat resistance of PCB substrate material is needed as an important guarantee.
With the emergence and development of high density installation technology represented by SMT and CMT, PCB is more and more inseparable from the support of high heat resistance of substrate in the aspects of small aperture, fine wiring and thin type.
With the improvement of Tg of substrate, the heat resistance, moisture resistance, chemical resistance and stability of PCB will be improved.
The higher the TG value, the better the temperature resistance of the plate. Therefore, in many lead-free processes, high TG is more widely used.
The critical temperature at which the substrate melts from a solid state to a rubber-like fluid is called the Tg point or the melting point
The higher the Tg point is, the higher the temperature requirement is when the plate is pressed together, and the pressed plate will be hard and brittle. To some extent, the quality of mechanical drilling (if any) in the later process and the electrical characteristics during use will be affected
Tg point is the highest temperature (℃) at which the substrate remains rigid.That is to say, under high temperature, common PCB substrate materials not only produce softening, deformation, melting and other phenomena, but also show in the mechanical and electrical characteristics of the sharp decline
Generally, the Tg plate is more than 130 degrees, the high-tg is generally greater than 170 degrees, and the medium Tg is about more than 150 degrees.
With the improvement of Tg of substrate, the heat resistance, moisture resistance, chemical resistance and stability of PCB will be improved.
1、10 Layer High Tg Hard Gold HDI Board