April/May, 2024 Continued from previous page


approach to reliability improvement with easy handling. LPM materials are versatile and can be applied to numerous designs and end products. Similar to plastic injection molding, the


part is placed in a mold (or tool) inside mold- ing equipment, and hot melt adhesive is heated to a liquid state and fed into the mold, where the part is encapsulated and can be handled immediately after ejecting. LPM is a fast, three-step, affordable solution managed in-house with the appropriate mold machine or via a third-party contractor. LPM uses very low pressure compared to


injection molding, so it is well-suited for del- icate electronics. In most cases, the molded material is waterproof, resistant to vibration and impact, and pro- tected from corrosion and most chemicals.


Conformal coatings are thin, polymeric materials applied to a printed circuit board (PCB) to protect it from environmental influences that may cause corro- sion or other degrading condi- tions. Formulated using a variety of chemistries (epoxy, acrylic, polyurethane, silicone, etc.), con- formal coatings are essential for high-reliability applications. These coatings are well-suit-


ed for applications where high reliability and a long lifetime is required. Since the materials protect against conditions that can cause electrical failures or voltage leaks, they allow for higher voltages and densities, so are essential where miniaturiza- tion is a factor.


Low-pressure molding.


www.us-tech.com Are Your Electronics Protected? That Depends.


Chip-on-Board (COB) encapsulants pro- tect bare chips on a substrate. Generally cat- egorized in one of two classes, glob top and


dam-and-fill, the materials are either applied as one dispensed deposit or with a material perimeter that is then filled, as the names suggest. COB encapsulants are recommended


when localized protection of sensitive compo- nents is required and when packages have to meet specific reliability targets. Because the encapsulants minimize corrosion by protect- ing against moisture and act as a dielectric by isolating wires from each other, they are often used to protect wirebonded die. COB encapsulants protect against ther-


mal shock, chemical contamination, and mechanical damage to enhance reliability. The materials provide electrical insulation, a Continued on page 51


Page 49


Conformal coating. Cleaning the PCB before


coating is recommended, and depending on the application, masking areas that are not to be coated might be required. Manual application of conformal coatings includes brush, aerosol, or spray atomization methods. Automated application can be carried out via dip coating (slow in comparison to spraying) or by selective spray equipment. Coating thickness is chemistry- and application-dependent, and cure mechanisms can vary. Conformal coatings provide


maximum environmental protec- tion against temperature ex - tremes, moisture, salt, chemicals, corrosion, and voltage leakage. They can be applied fast and cured quickly for compatibility with high-volume and/or high-mix environments and provide high reliability for PCB assemblies.


See at IPC APEX, Booth 523


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