Let's first explain the electrical appliances we use every day. Wake up early in the morning and turn on the electronic fluorescent lamp. When brushing your teeth, the charger of the rechargeable electric toothbrush, use the remote control to turn on the TV to watch the news, use the induction cooker or microwave to heat breakfast, and go out to take the elevator. When you walk into the office, look around at every kind of machine, telephone, and fax that needed to be plugged in. Basically, the products that need to be used are the possible uses of SMPS. The required specifications and circuit structure vary depending on the place of use, and the price will vary greatly.

It is used to assess the anti-corrosion ability of materials and their protective layers, as well as the process quality comparison of similar protective layers. It can also be used to assess the salt spray corrosion resistance of certain products.

The salt solution is prepared with sodium chloride and distilled water, and its concentration is 5±0.1% (weight). The collected liquid after physicalization shall not be reused except for the back part of the baffle.

The pH value of the salt solution before atomization is between 6.5 and 7.2 (35 ℃). When configuring the solution, it is allowed to use chemically pure or above dilute hydrochloric acid or sodium hydroxide aqueous solution to adjust the pH value, but the concentration must still be in line with the 80cm2 funnel to collect the salt spray precipitation for 16 hours of continuous atomization, any position in the effective space The sedimentation rate is: 1.0~2.0ml/h.80cm2.

This standard uses continuous atomization, and the recommended standard time is 16, 24, 48, 96, 168, 336, 672h. The atomization must prevent oil pollution, dust impurity and the temperature and humidity of the sprayed air.

Table 3 - Degree of protection against water indicated by the second characteristic number.

Second characteristic number	Degree of protection
	Brief description	Definition
0	Non-protected	-
1	Protected against vertically falling water drops	Vertically falling drops shall have no harmful effects.
2	Protected against vertically falling water drops when enclosure tilted up to 15°	Vertically falling drops shall have no harmful effects when enclosure is tilted at any angle up to 15°on either side of vertical.
3	Protected against spraying water	Water spray at an angle up to 60°on either side of the vertically shall have no harmful effects.
4	Protected against splashing water	Water splashed against the enclosure from any direction shall have no harmful effects.
5	Protected against water jets	Water protected in jets against the enclosure from any direction shall have no harmful effects.
6	Protected against powerful water jets	Water protected in powerful jets against the enclosure from any direction shall have no harmful effects.
7	Protected against the effects of temporary immersion in water	Ingress of water in quantities causing harmful effects shall not be possible when the enclosure is temporarily immersed in water under standardized conditions of pressure and time.
8	Protected against the effects of continuous immersion in water	Ingress of water in quantities causing harmful effects shall not be possible when the enclosure is continuously immersed in water under conditions which shall be agreed between manufacturer and user but which are more severe than for numeral 7.
9	Protected against high temperature and pressure water jets	Water protected at high pressure and temperature against the enclosure from any direction shall have no harmful effects.

Weight gain equipment such as analytical balance or equivalent with an accuracy of one microgram or better, see ASTM B-810, Calibration of Atmospheric Corrosion Tests by Mass Change in the Mass of Copper Coupons.

The environmental chamber shall consist of an enclosure made of nonreactive (will not react with pollutant gases) materials contained within a cabinet, oven, or incubator capable of maintaining the temperature within the specified ranges: see table1. A commercially available environmental chamber will suffice as the outer chamber, if applicable.

Table 1 Test method and parameters

Test parameters	Method 1	Method 2	Method 3	Method 4
H2S(10-9vol/vol)a	100±20	10±5	100±20	10±5
NO2(10-9vol/vol)b	--	200±50	200±50	200±20
Cl2(10-9vol/vol)c	-	10±5	20±5	10±5
SO2(10-9vol/vol)d	500±100	-	-	200±20
Temperature（℃）	25±1	30±1	30±1	25±1
Relative humidity（%）	75±3	70±3	75±3	75±3
Number of volume changes per hour of test gas（10）	3~10	3~10	3~10	3~10
Weight gain of copper sheet sample obtained according to Appendix A（mg/(dm2·d)）	1.0~2.0	0.3~1.0	1.2~2.2	1.2~2.4
Note: Due to the different corrosivity of test methods 1 to 4, the order of numbering and the corresponding corrosion weight of copper pieces do not reflect its severity level
a H2S: 1μm/m3=0.71mm3/m3
b NO2: 1μm/m3=0.53mm3/m3(10-9vol/vol)b=UNIT(μm/m3)
c Cl2: 1μm/m3=0.34mm3/m3
d SO2: 1μm/m3=0.38mm3/m3