Basic knowledge and application guide of SMT red glue
About SMT patch red glue: SMT patch red glue is a kind of poly dilute compound. Unlike solder paste, it solidifies when heated. Its freezing point temperature is 150 ° C. At this time, the red glue starts to change directly from the paste Into a solid.
Properties of SMT patch red glue
SMT patch red glue has viscosity fluidity, temperature characteristics, wetting characteristics, etc. According to this characteristic of red glue, the purpose of using red glue in production is to make the parts firmly adhere to the PCB surface and prevent it from falling.
Application of SMT red glue
Use on a printing machine or dispenser. 1. To maintain the quality of the adhesive, please store it in a refrigerator (5 ± 3 ℃) for storage. 2. Remove it from the refrigerator and return to room temperature for 2 ~ 3 before use. Hour 3. Toluene or ethyl acetate can be used to clean the rubber tube for dispensing: 1. Add a back plug to the tube to obtain a more stable dispensing volume 2. The recommended dispensing temperature is 30-35 ° C 3. Dispensing points For rubber hoses, please use a special glue-moisture filling machine to separate the glue to prevent air bubbles from scraping into the glue. The recommended scraping temperature is 30-35 ° C. Note: After removing the red glue from the refrigerated environment, do not open it until it reaches room temperature. use. To avoid contamination of the original product, do not return any used patch glue to its original packaging.
Process method of SMT red glue
1) Printing method: The stencil engraved holes should be determined according to the type of the part and the properties of the substrate, its thickness and the size and shape of the holes. Its advantages are fast speed and high efficiency. 2) Dispensing method: Dispensing uses compressed air to apply red glue to the substrate through a dedicated dispensing head. The size and number of glue spots are controlled by parameters such as time and pressure tube diameter. The dispenser has flexibility Functions. For different parts, we can use different dispensing heads, set parameters to change, or change the shape and number of glue points to achieve the effect, the advantage is convenient, flexible and stable. The disadvantage is that it is prone to drawing and bubbles. We can adjust the operating parameters, speed, time, air pressure, and temperature to minimize these shortcomings. 3) The needle rotation method is to immerse a special needle film in a shallow plastic disk. Each needle has a glue point. When the glue point contacts the substrate, it will detach from the needle. The amount of glue can be determined by the shape and diameter of the needle. To change. Curing temperature 100 ℃ 120 ℃ 150 ℃ Curing time 5 minutes 150 seconds 60 seconds Typical curing conditions: Note points: 1. The higher the curing temperature and the longer the curing time, the stronger the bonding strength. 2. Since the temperature of the chip adhesive varies with the size of the substrate parts and the placement position, we recommend finding the most suitable hardening conditions. Storage of red gum: 7 days at room temperature, more than 6 months at less than 5 ° C, and more than 30 days at 5-25 ° C.
Management of SMT patch red glue. Due to the temperature, the SMT patch red glue has its own viscosity, fluidity, wetting and other characteristics, so the SMT patch red glue must have certain conditions and standardized management. 1) Red gum must have a specific serial number, which is numbered according to the quantity, date and type of the feed. 2) The red glue should be stored in a refrigerator at 2 ~ 8 ℃ to prevent its characteristics from being affected by temperature changes. 3) The temperature of red glue should be 4 hours at room temperature. Use it in FIFO order. 4) For the dispensing operation, the red glue of the rubber tube should be defoamed, and the unused red glue should be put back in the refrigerator for storage. Old and new glue cannot be mixed. 5) To accurately fill in the temperature recovery record form, the person and time of temperature recovery, the user must confirm that the temperature recovery is OK before using. In general, red glue cannot be used expired.