LED packaging process, how to do a good job of anti-sulfur measures
In the LED package process, curing occurs mainly in the crystal and dispensing encapsulation process, the occurrence of vulcanization is mainly silver-containing materials (silver-plated stent and conductive silver paste) and silicone rubber material. Silver-containing materials are vulcanized to form black silver sulfide, resulting in yellowing and darkening in the vulcanized region. Silicone gums are "poisoned" by the vulcanization of the silicone material, resulting in curing failure and failure to fully cure. Which silicone curing agent poisoning: LED packaging silicone curing agent containing platinum (platinum) complexes, and this platinum complex is very easy to poison, poisoning agent is any of nitrogen (N), phosphorus (P ), Sulfur (S) compounds, once the curing agent poisoning, the silicone curing incomplete, it will cause high linear expansion coefficient, the stress increases.
To SMD lamp bead packaging process, for example, in the production process LED may be vulcanized material:
1. Solid-crystal process, silver-plated stent is cured, black hair shiny black stent, will lead to reduced reliability;
2. Crystallization process, silver plastic is cured, silver plastic black, dark colors, will lead to reduced reliability or failure;
3. Solid-crystal process, the nature of silicon is solidified silicone curing, resulting in curing obstacles, can not be completely cured, will lead to decreased adhesion or failure;
4. Dispensing, powder, packaging processes, silicon powder is cured, will lead to curing obstacles, can not be completely cured, the product failure;
5. Point powder process, phosphor sulfur, will lead to curing obstacles, product failure.
LED packaging plant, in the LED production process must pay great attention to the two aspects of sulfuration prevention, prevention is:
1. To avoid LED exposure to acidic (PH <7) workshop environment. Nitrogen acid gas will first react with silver, and then with the sulfur / chlorine / bromine substitution reaction generated black silver sulfide, silver chloride or silver bromide.
2. For the procurement of other LED supporting materials, manufacturers may require the provision of Jin Jian LED accessories row sulfur / bromine / chlorine test report to confirm whether it contains sulfur, halogen and other substances to prevent its occurrence with the LED material chemical or Physical reaction, resulting in LED products silver coating corrosion, LED silica gel, phosphor material properties change, resulting in the failure of LED optoelectronic properties.
3. Use desulfurization gloves, finger sets, sulfur-free masks; distinguish between sulfur-free materials, box-jacketed; use of sulfur-free cleaning agent; sulfur PCB board cleaning, desulfurization and then use; Bake independently.
4. Silicone prone to "poisoning" substances are: containing N, P, S and other organic compounds; Sn, Pb, Hg, Sb, Bi, As and other heavy metal ion compounds; containing ethinyl and other unsaturated groups of organic compounds. Pay attention to the following materials:
Organic rubber: sulfur vulcanized rubber such as gloves
Epoxy resin, polyurethane resin: Amine, isocyanate curing agent
Synthetic silicone RTV rubber: In particular, the use of Sn-based catalyst
Soft Polyethylene: plasticizers, stabilizers
Engineering Plastics: Flame Retardants, enhanced heat-resistant agents, UV absorbers
Silver plating, gold-plated surface (the manufacture of the plating solution is the main reason)
• Degassed by the Solder register (caused by silicone heating and curing)
Vulcanization is an irreversible chemical reaction, and once vulcanized, the product will be scrapped and irreparably removed. As a professional third-party LED analysis and testing organization, Jinjian LED Lab has a large number of professional microstructure testing and analysis equipment and a large number of LED row sulfur case analysis experience, which can rapidly bring sulfur / chlorine / bromine to LED packaging process Of the sources of pollution investigation and identification, given the optimization program for the packaging manufacturers to reduce the loss of millions.