Flip Chip Technology

What are the differences between
traditional face-up and flip chip LED COB packaging technologies?

01
Difference on LED packaging structure
02
Improving the thermal conductivity by reducing the heat dissipation path

Features of YUJILEDS flip chip COB packaging:

Comparing with standard face-up LED packaging technology, wire bonding has been avoided in YUJILEDS flip chip packaging technology, thus no risk of gold wire breakage.

Comparing with standard flip chip packaging technology, eutectic bonding between LED chip and substrate in YUJILEDS flip chip packaging technology result in excellent thermal conductivity for this whole device.

For the high power COB, the culprit of reliability decay is heat:

The flip chip structure of the COB transfers the heat directly to the substrate, so the efficiency can be largely increased.

The AlN substrate of the COB has a heat transfer efficiency as high as about 300 W/(m•K), twice of Al substrate, and six times that of Al₂O₃ substrate.

Why small light emitting surface (LES)?

Manufacturing cost
Easier optical design: smaller LES means easier secondary optical design, makes more compact and portable light fixture realizable.
Higher mobility
Less manufacturing cost: less BOM and manufacturing cost should be used in more compact light fixture.

More than just small,
excellent performance also achieved

High CRI
High reliability
Extremely small color shift

High CRI

With reliable phosphor properties, appropriate mixing ratio and the unique packaging process technology, this COB has a CRI (Ra) as high as 95 even at a CCT of 5600K.

High reliability

The maintenance rate of the initial lumen flux of the high lumen density COB at 12 amperes drive current is more than 98% after 9000 hours continuous light up.

Extremely small color shift

The high lumen density COB shows a color temperature shift smaller than +/-50K after 9000 hours and the chromaticity shift from black body curve is less than +/-0.001.

Development concept

A chip on board (COB) light source has a small light emitting surface (LES) and large luminous flux, thus it is usually used in directional lighting fixtures. However, keeping a COB small is extremely challenging, because the compact arrangement accelerates heat accumulation and compromises the performance. Therefore when designing a COB, it is always the key point to improve the luminous flux and the reliability while controlling the LES.

Based on this principle, YUJILEDS high lumen density COB was developed, the world's highest lumen density LED.

Potential applications
of flip chip COB

Stage lighting
Horticultural lighting
Sport lighting
Inspection lighting

Flip Chip COB

What are the differences between traditional face-up and flip chip LED COB packaging technologies?

01Difference on LED packaging structure

02Improving the thermal conductivity by reducing the heat dissipation path

Features of YUJILEDS flip chip COB packaging:

For the high power COB, the culprit of reliability decay is heat:

Why small light emitting surface (LES)?

Manufacturing cost

Higher mobility

More than just small, excellent performance also achieved