There is no uniform standard for the Nitrogen Concentration of Nitrogen-Filled Ovens/Industrial Nitrogen Oven. The core is to set it according to the oxidation sensitivity of materials, processing temperature and industry standards, ranging from 95% to 99.999%. The key is to inhibit oxidation reactions through an inert atmosphere for Inert Atmosphere Oven while balancing cost and effect.

I. Classification by Material Oxidation Sensitivity: 3 Core Adaptation Standards

1. Low-sensitivity materials (slight oxidation allowed, cost performance pursued)

Adapted concentration: 95% ~ 98%Typical materials: High-temperature degreasing and drying of ordinary metal parts (e.g., carbon steel, aluminum alloy); high-temperature shaping of some plastic parts (e.g., PP, PE).Setting logic: Such materials have a slow oxidation rate at high temperatures. A low Nitrogen Concentration can block most of the air (oxygen accounts for about 21% in the air), avoid obvious oxidative discoloration or performance attenuation, and reduce the use cost of high-purity nitrogen at the same time.Note: If the metal surface luster needs to be maintained after processing, the concentration is recommended to be not less than 97%.

2. Medium-sensitivity materials (oxidation needs to be inhibited to ensure basic performance)

Adapted concentration: 98% ~ 99.5%Typical materials: High-temperature aging of electronic components (e.g., PCB circuit boards, capacitors); drying of lithium battery electrode sheets (before liquid injection); high-temperature curing of resin/composite materials.Setting logic: The key components in the materials (e.g., circuit board pads, active substances of battery electrode sheets) are sensitive to oxygen, and are prone to oxidation at high temperatures leading to performance failure (e.g., pad oxidation affects conductivity, electrode sheet oxidation reduces battery capacity). A higher Nitrogen Concentration is required to control the residual oxygen content within 0.5% ~ 2%. Industry reference: Nitrogen Concentration ≥ 99% is usually required for the drying of lithium battery electrode sheets, and some enterprises will increase it to 99.5% to ensure both low moisture and oxygen content.

3. High-sensitivity materials (oxidation is strictly prohibited, extreme inert environment required)

Adapted concentration: 99.9% ~ 99.999% (i.e., 3N ~ 5N purity)Typical materials: High-temperature processing of semiconductor chips (e.g., silicon wafers); baking of precious metal parts (e.g., gold and silver contacts); low-temperature drying of pharmaceuticals/food (e.g., high-end health products, oxidation-prone snacks); sintering of powder metallurgy (e.g., titanium alloy powder).Setting logic: The materials are of high value or extremely sensitive to oxidation. Even a trace amount of oxygen (e.g., below 0.1%) will cause irreversible damage (e.g., chip oxidation affects circuit performance, precious metal oxidation discolors, pharmaceutical oxidation fails). High-purity nitrogen is required to control the residual oxygen content within 100ppm ~ 10ppm.Special requirements: Some semiconductor scenarios are equipped with a Nitrogen circulation purification system for oven, to monitor and supplement high-purity nitrogen in real time, maintaining a stable Nitrogen Concentration at 99.999%.

II. Key Influencing Factors: 2 Supplementary Principles for Concentration Setting

1. The higher the processing temperature, the higher the concentration required

Temperature accelerates the oxidation reaction. For example, for the same metal part, a Nitrogen Concentration of 97% is sufficient for processing at 100℃, but if the temperature is increased to 300℃, the concentration needs to be raised to more than 99% to offset the oxidation acceleration effect caused by high temperature.

2. Strictly follow industry standards or customer requirements

If there are clear industry specifications, they must be followed for setting:

• Electronics industry: In the IPC standard, the recommended Nitrogen Concentration for PCB high-temperature baking is ≥ 99%;

• Semiconductor industry: In the SEMI standard, the nitrogen purity required for silicon wafer heat treatment is ≥ 99.999%;

• Food industry: In GB 7718, the Nitrogen Concentration in the processing environment of nitrogen-filled food shall be ≥ 98%, and the residual oxygen shall be ≤ 2%.

III. Common Misunderstandings: Avoid 2 Concentration Setting Errors

1. Believing that "the higher the concentration, the better, and blindly choosing 99.999%"

The procurement and operation cost of high-purity nitrogen (e.g., 5N) is 3 to 5 times that of 99% concentration. If the material only requires medium and low concentration (e.g., ordinary metal parts), choosing a high concentration will cause resource waste and instead increase production costs.

2. Ignoring "cavity tightness" and only focusing on nitrogen concentration

If the Nitrogen-Filled Oven cavity has poor tightness (e.g., door gaps, pipeline leaks), even if 99.9% high-purity nitrogen is introduced, external air will seep in, leading to a sharp drop in the actual Nitrogen Concentration. Before setting the concentration, it is necessary to check the cavity tightness first to ensure that the Nitrogen oven leakage rate standard is ≤ 0.5%/h.