Situation:

An LED light bulb manufacturer was facing complaints of pre-mature bulb failure due to moisture penetration through the bondline at the interface of the bulb cover and body. They were looking for a bonding solution that would be able to maintain bond strength at bulb’s operating temperatures.

Substrates: Crystal Glass || PBT (Polybutylene Terephthalate)

Challenges:

The manufacturer was using an instant adhesive which had the following challenges:

• Low thermal resistance of the existing solution created bondline failures
• The lens bondline failures allowed moisture penetration into the bulb leading to electrical failure

Solution:

The Henkel solutions expert recommended using LOCTITE HY 4090 hybrid adhesive that would give the right strength and also have the speed advantage of the previously used instant adhesive. LOCTITE HY 4090 is applied to the lens groove of the plastic light case e through a dual cartridge dispenser equipped with a mixer nozzle and the cover glass lens is manually pressed into position.

The assembly bonded with LOCTITE HY 4090 was able to maintain bond strength under bulb operating temperature test.

Results:

Bonding with LOCTITE HY 4090:

• Eliminated pre-mature electrical failure by maintaining bond strength
• Sealed against preventing moisture penetration