A PHENOLIC RESIN POWDER FOR DIP COATING APPLICATION
PHENOLIC POWDER DRZ – 51 is a blend thermosetting Phenolic Resin Powder Compound, specially for Electronic Component coating. The compound is ideally suitable for Indian climatic conditions and has a shelf life of minimum one year.
PHENOLIC POWDER DRZ – 51 has the following advantages over the available powders which are imported from abroad
- Longer shelf life
- Shorter drying and curing time
- Excellent solvent resistance
- Use of cheaper solvent possible
- Indigenous development, first time in the country
- Use of only indigenous raw materials
- Suitable for Indian climatic conditions
PHENOLIC POWDER DRZ – 51 is suitable for coating electronic components like capacitors, resistors, coils, thick films, chips, PCB, etc. The coatings imparts electrical, mechanical protection, solvent and humidity resistance to the components.
Preparation Of Dip Coating Paste
- The powder compound must be mixed with polar type of solvents to the desired consistency for dip coating
- Main solvents to used are Methanol, Ethanol and Acetone. The combination of these solvents give different viscosities and evaporation rates
- We recommend 100 parts by weight of DRZ – 51, 25 parts by weight of Methanol and 25 parts by weight of Acetone as starting mixing combination
- For obtaining the best surface finish and coating characteristics, please follow the following guidelines
- Prepare a concentrated paste in the solvents, the night before use and allow it to "Soak" for overnight
- Put the paste in sigma or Rotomixer and add solvents for reducing viscosity for 1 to 2 hours for homogenous mixing
- Adjust the viscosity of mix depending upon the type and size of component to be Coated and film thickness desired
- In case of using hold tank for dipping station, monitor the solvent loss by adding fresh solvents and hence maintaining the viscosity
Dip Coating Process
- The coating of PHENOLIC POWDER DRZ – 51 could be applied on components by a single or multiple dip process
- We recommend the multiple dip process to obtain the desired coating thickness, which will minimize the problems like sagging, pin hole formation and cracking
- Between two successive dips the air drying time must be adequate to allow the solvents to escape from the coating. This could be judged by the surface of component ( matt finish and touch dry )
- Generally 2 to 5 minutes interval between two successive dips is sufficient. For the best coating ensure that the coating pot is kept under constant stirring to avoid settling of fillers
Drying Cycle
- After the dip coating process, the components should be dried in open air or forced warm air.
- The pre-drying time depends upon the type of solvents used and the component size. This could be from 3 to 5 hours.
- The polar solvents have the following drying characteristics
| a) | Very fast evaporating | Methanol | 1 |
| Acetone | |||
| b) | Medium evaporating | Acetone | 1 |
| Isopropanol | 1 | ||
| c) | Slow evaporating | Ethanol |
Curing or baking Cycle
- After the coating and drying cycle of component, it must be baked to cure the binder resin of PHENOLIC POWDER DRZ – 51 .
- The pre-drying time depends upon the type of solvents used and the component size. This could be from 3 to 5 hours.
- The curing cycle depends upon
- Components size and film thickness
- Evaporation rate of the solvent combination
- Desired solvent resistance properties
- For PHENOLIC POWDER DRZ – 51 we recommend curing at 3 hours at 125°C for optimum properties
- However, 1 hour at 125 °C is adequate for smaller components and 4 hours at 125 °C is recommended for bigger components
- An ideal curing is as given in Fig 1. Infra-red oven curing gives faster rate of production for DRZ-51 coated components
Note : This information is intended only for general guidance in the application of our product. It has been obtained by careful investigation and represents the present state of our knowledge and experience. Because of large number of possible methods of application and processing, we are not able to assume responsibility in any one particular case for either the technical results or the patent rights situation application to the country under consideration.