Considering the difference in process and storage conditions of circuit board products, printed circuit boards should be used in time (recommended within 24 hours) after unpacking, and pre-drying treatment is recommended before use, especially for PI substrates in flexible circuit boards. Board, if patch welding is required, it must be pre-dried.
| PCB surface treatment process |
| physical properties |
Hot air leveling (tin spraying) |
chemical tin |
chemical silver |
Organic Solderable Preservative (OSP) |
Electroplated nickel gold (electroplated gold) |
Electroless Nickel Gold (Immersion Gold) (ENIG) |
| Storage life (months) |
12 |
12 |
12 |
6 |
6 |
6 |
| The number of reflows that can be experienced |
4 |
5 |
5 |
4 |
4 |
4 |
| cost |
medium |
medium |
medium |
Low |
high |
high |
| Process complexity |
high |
medium |
medium |
Low |
high |
high |
| process temperature |
250℃ |
50℃ |
70℃ |
40℃ |
55-60℃ |
80℃ |
| Thickness range |
1-25 |
0.05-0.2 |
0.8-1.2 |
0.2-0.5 |
NI:4-5
AU＞0.05 |
NI:3-5
AU:0.05-0.2 |
Board storage time
For chemical immersion tin or immersion silver products, it is recommended to use them up within 12 hours after unpacking, otherwise they must be repacked.
If the effective storage period is exceeded, the user can dry it and try it out; if necessary, re-test some properties, and it can still be used after passing the inspection. Usually the circuit board is stored for more than 3 months. In order to avoid the hidden danger of moisture before putting it on the machine, it needs to be baked at 150 degrees for 2 hours.
Shelf life and storage environment of circuit boards:
A. Good storage conditions: Refers to indoor environmental conditions with temperature less than 25 degrees, relative humidity not greater than 65%, temperature control, and no corrosive gases. B. General storage conditions: refers to the indoor environmental conditions where the temperature is not higher than 35 degrees, the relative humidity is not higher than 75%, and there is no corrosive gas.
