9.2 Group III Nitride LED Encapsulation Process
191
Fig. 9.3 Microscope image of high-power LED chips
Before dipping silver paste
After dipping silver paste
Fig. 9.4 Lead frame before and after dipping silver paste
other hand, for LED chips grown on insulated substrate such as sapphire, high-power
chips would use silver paste in order to achieve good thermal performance. For small
chips, insulating paste is chosen. This is mainly driven by cost consideration.
In actual production stage, automatic die bonding equipment is commonly used,
which is shown in Fig. 9.5. The equipment dispenses adhesive onto the lead frame
before grabbing and placing LED chip onto the lead frame.
(3) Curing of die bonding adhesive: die attach adhesive is cured primarily to
make sure LED chips being firmly bonded onto the lead frame. The curing condition
Fig. 9.5 Automatic die
bonding equipment is
grabbing LED chips
191
Fig. 9.3 Microscope image of high-power LED chips
Before dipping silver paste
After dipping silver paste
Fig. 9.4 Lead frame before and after dipping silver paste
other hand, for LED chips grown on insulated substrate such as sapphire, high-power
chips would use silver paste in order to achieve good thermal performance. For small
chips, insulating paste is chosen. This is mainly driven by cost consideration.
In actual production stage, automatic die bonding equipment is commonly used,
which is shown in Fig. 9.5. The equipment dispenses adhesive onto the lead frame
before grabbing and placing LED chip onto the lead frame.
(3) Curing of die bonding adhesive: die attach adhesive is cured primarily to
make sure LED chips being firmly bonded onto the lead frame. The curing condition
Fig. 9.5 Automatic die
bonding equipment is
grabbing LED chips