Basic knowledge of SMT patch and application guide
About SMT patch red rubber: SMT patch red rubber is a kind of rare compounds, and the solder paste is different is the heated after curing, its freezing point temperature is 150 ℃, at this point, the red glue started directly by the paste body becomes solid.
Properties of SMT patch red gum
SMT adhesive has viscosity, fluidity, temperature and wetting properties.According to this characteristic of red glue, the purpose of using red glue in production is to make parts stick firmly on the surface of PCB to prevent them from falling.
Application of SMT patch red gum
Used in printing or dispensing machines 1, to maintain the quality of the rubber patch, please placed in the refrigerator cold storage (5 + 3 ℃) 2, from the refrigerator before use, should be 2 ~ 3 hours, 3 at room temperature next time, you can use the toluene or ethyl acetate to wash hose dispensing: 1, after joining in some rubber plug, can obtain more stable point glue dispensing volume 2, recommended temperature of 30-35 ℃ 3, FenZhuangDian hose, please use the special glue water machine for partial shipments, in order to prevent the mixed with air bubbles in the glue spreading: recommended by scraping the glue temperature of 30-35 ℃ to note:Once the red gum has been removed from the refrigerated environment, it cannot be opened before reaching room temperature.In order to avoid contamination of the original product, any used adhesive is not allowed to be poured back into the original packaging.
Process method of SMT patch red gum
1) printing method: the steel mesh punching hole shall be determined according to the type of the part, the performance of the base material, the thickness, the size and shape of the hole.The advantages are high speed and efficiency.2) dispensing method: the dispensing method USES compressed air to apply the red glue to the substrate through the special dispensing head, which is controlled by the size, number, time, pressure pipe diameter and other parameters. The dispensing machine has flexible functions.For different parts, we can use different point glue head, set the parameter to change, also can change the shape and quantity of glue point, in order to achieve the effect, the advantage is convenient, flexible, stable.Disadvantages are easy to pull and air bubbles.We can adjust the operating parameters, speed, time, pressure and temperature to minimize these disadvantages.3) needle rotation: a special needle film is dipped into a shallow glue plate, and each needle has a glue point. When the glue point touches the substrate, it will detach the needle. The amount of glue can be changed by the shape and diameter of the needle.Curing temperature 100 ℃ 120 ℃ 150 ℃ cure time 5 minutes, 150 seconds to 60 seconds typical curing conditions: note: 1, the higher the curing temperature and curing time and the bonding strength is stronger.2. As the temperature of the patch adhesive varies with the size of the substrate part and the placement of the patch, it is recommended to find the most suitable hardening conditions.Red glue storage: can be stored at room temperature for 7 days, in less than 5 ℃ storage is more than 6 month, in 5 ~ 25 ℃ can store more than 30 days.
Management of SMT patch red gum
Due to the viscosity, fluidity, wetting and other characteristics of SMT adhesive affected by temperature, the SMT adhesive should have certain operating conditions and standard management.1) the red gum shall be labeled with specified flow number, which shall be numbered according to the quantity, date and type of incoming material.2) red glue should be put in 2 ~ 8 ℃ refrigerator save, prevent due to temperature changes, impact properties.3) the temperature of the red gum shall be returned to the room temperature for 4 hours, and it shall be used in the order of first in first out.4) for the point glue operation, the rubber tube red glue should be defoamed, and the once unused red glue should be put back into the refrigerator for preservation, and the old and new glue cannot be mixed.5) to accurately fill in the temperature return record form, the temperature return person and temperature return time should be confirmed by the user before use.In general, red glue should not be used out of date.