The gluing procedure can be defined by the following steps:

a) Pre-glue Preparation The following items need to be procured before starting the gluing process:

1. Epoxy (TI recommends EPO-TEK 323LP-LH Premium Part A®)
2. Epoxy hardener (TI recommends EPO-TEK 323LP-LH Premium Part B®)
3. Glue fixture
4. Lens
5. Transducer
6. PI film
7. Scale (with 0.1 g of accuracy)
8. Isopropyl alcohol (IPA)
9. Delicate wipes
10. Chemical handling gloves
11. Applicator syringe (TI recommends 16Ga blunt needle in the step)
12. Plastic cup
13. Plastic rod

b) Glue Preparation Procedure

Mix glue per data sheet specifications.

c) Oven Preparation Procedure

1. The oven for curing the epoxy mixture must be preheated to 85°C.
2. Depending on the thermal mass (physical dimensions inside the oven), the preheating procedure can start earlier than glue preparation procedure.
3. Make sure that the oven is clean and there are no other devices, or any water residual inside.

d) Gluing the Transducer to the Lens Procedure

1. Wear gloves and eye protection for personal protection and to avoid surface contamination.
2. Make sure that the glue fixture, transducer and etched glass are cleaned with isopropyl alcohol.
3. Place the piezo into the glue fixture.
4. Apply a thin amount of glue around the top of the transducer.
5. Place the etched glass into the glue fixture with the etched side towards the glue.
6. Make sure the cover lens is as concentric as possible with the transducer.
7. Make sure that there are not air gaps in the glue by viewing the top of the transducer through a microscope.

8. Make sure that no glue has gone into the gap between the transducer and the glue fixture. By viewing the assembly through a microscope. If that glue is present in this gap, remove the glass and transducer and return to step 1. Make sure the fixture is clean of any glue. Otherwise, the transducer gets glued to the fixture.

e) Glue Curing Procedure

1. Place the glue fixture, which contains the transducer, glue and glass in the oven.
2. Turn the oven temperature up to 150° C per the glue curing specifications. Avoid rapid heating of the cover lens to avoid any possible cracking of the material.
3. Keep the glue fixture, which contains the transducer, glue and glass, inside the oven for 1 hour at 150° C.

f) Glue Cool Down Procedure

1. To remove the glue fixture from the oven, use proper heat-resistant gloves for personal protection.
2. Remove the glue fixture from the oven and allow the glue fixture to reach room temperature.
3. After the glue fixture has reached room temperature, remove the transducer assembly from the glue fixture. If the transducer appears stuck, remove the transducer by pushing against the inside of the glass through the hole of the glue fixture.
4. Discharge the transducer by shorting the two plates of the transducer.
   Note: Warning! High voltage, low-power, electrical discharge can occur due to the transducer temperature change.

g) Gluing the Thin Film to the Lens/Transducers Procedure

1. Apply a thin amount of glue on the gluing area of the thin film evenly.
2. Place the thin film on top of the lens.
3. Make sure the thin film is as concentric as possible with the lens.
4. Make sure that no excessive glue has gone into the gap between the thin film and the glue fixture.
5. Put the assembly in the oven and repeat the curing procedure
6. Take the assembly out and repeat the cool down procedure