How Can I Select Adhesives for Electronic Components?
Industrial adhesives play an integral part in electronics manufacturing. Their various uses in electronics production range from bonding, sealing, encapsulating and protecting electronic components to offering properties such as electrical conductivity, thermal conductivity, low outgassing rates and moisture resistance.
Electronic manufacturing industries utilize various adhesives that suit specific purposes and requirements, with each suitable for certain applications and purposes. We understand the difficulty in choosing an electronic adhesive can be challenging – therefore this blog provides information to assist with choosing an adhesive to meet those requirements. First though, let’s look at various kinds of bonding adhesives used when bonding electronic components together.
A Types Of Adhesives And Application Process Used To Attach Electronic Components
Conformal coating is a thin polymer layer applied to printed circuit boards (PCBs) in order to protect it against dust, moisture, chemicals, stress, shock and vibrations. Care should be taken when applying this protective layer as its sole goal should be protecting solder joints and components on its surfaces from damage caused by external factors like dust or moisture intrusion and temperature extremes. When considering adhesive solutions suitable for PCBs it must cure rapidly while offering excellent temperature resistance properties – otherwise any adhesion issues would likely arise quickly enough!
Electronic adhesives play a pivotal role in bonding semiconductor chips – commonly referred to as die – to their microelectronic semiconductor packages during what’s referred to as die attach, an integral process known by its shorthand name. Electronic glue also reduces stress levels during system operation by bonding directly onto die surfaces with excellent electrical conductivity, thermal resistance and low impurity levels for an ideal experience; jetting or stamping are often utilized during die attach.
Sealants play an indispensable role in protecting electrical components from moisture, water, and any harmful corrosive agents, and act as insulation devices in case there are issues in their circuitry.
Glob top refers to any protective encapsulation on semiconductors which offers protection for sensitive dies and wire bonds from moisture, physical damage, temperature variations and contaminants such as moisture. Glob top can either be applied through chip-on-board (COB) applications using dam-and-fill mechanisms or directly applied. When choosing adhesive systems suitable for using in glob top applications it should also take thermal as well as electrical properties into consideration.
Surface mounting refers to the practice of attaching electrical components directly onto printed circuit boards (PCB). Surface mount adhesive (SMA) can be used instead of solder for bonding these parts together and also acts as an interim fix before soldering occurs. SMA adhesives can be applied using dot method application before curing with heat curing systems.
Underfills are used to coat and encase flip-chip, CSP and BGA devices for mechanical stability and reinforcement by filling any gaps between semiconductors. A good underfill should feature low coefficients of thermal expansion, low ionic content and superior shock resistance as key factors when choosing adhesives suited for this process.
EMI/RFI ShieldingEMI/RFI shielding acts to create a barrier around circuits to shield them from external electromagnetic interference, using adhesives designed specifically to block electromagnetic or radio frequencies entering or exiting. EMI/RFI adhesives should provide sufficient electrical conductivity as well as structural bonding properties to provide effective shielding solutions.
PCB and Semiconductor Manufacturing and Packaging
Adhesives play an essential part in PCB & semiconductor manufacturing and packaging industry, from bonding components together, encasing PCB boards in plastic encapsulations layers, tacking wire to components ready for soldering, wire tacking and wire tacking through to soldering components into position for soldering. In order to meet quality performance criteria adhesives must have thermal conductivity, high purity levels, low CTE values as well as excellent electrical conductivity characteristics for optimal quality performance.
Factors to Keep in Mind when Selecting Adhesives for Electronic Components
- Thermal Conductivity Thermal conductivity refers to the physical property of materials to transfer heat. Electronic adhesives that boast great thermal conductivity can prevent overheating by dispensing excess heat away from components safely, keeping equipment protected against damage from overheating. Usually heat sinks are employed as heat dissipators devices to assist this process.
Thermal conductivity helps components remain at an ideal working temperature and protects them from premature failure due to overheating, therefore making testing thermal conductivity essential when selecting adhesives for electronic applications as most electronic components produce significant heat energy. One component epoxy systems offer excellent solutions with good thermal conductivity properties.
- Electrical Conductivity
Adhesives designed with electrical conductivity aim to facilitate the free flow of electric current. Since many electronic components rely on this ability, an adhesive with the necessary electrical conductivity is absolutely critical in supporting proper functioning for many electronics components and their respective PCB packages.
Adhesives that provide good electrical conductivity typically contain silver, nickel or graphite as fillers; silver-filled adhesive offers superior conductivity at the expense of being more costly while graphite filled adhesive offers an economical yet still effective electrical conducting solution.
- Adhesive Materials
Adhesive materials have an enormous effect on the properties of adhesives used for electrical uses, necessitating certain specific chemical and mechanical characteristics which are provided through specific materials. Based on its intended function, selecting adhesive materials depends upon what properties your desired adhesive should possess.
Epoxy-based adhesives offer excellent bonding strength, thermal stability, and electrical insulation properties; silicon adhesives excel at flexible high temperature resistance as well as providing electrical isolation properties; polyurethane glue offers the optimal combination of mechanical strength flexibility & electrical insulation properties for use on surfaces such as electronics.
- Moisture Resistance
Environmental considerations play an integral part of selecting electronic adhesives, since moisture damage to PCBs and electrical components is detrimental. Short circuits, corrosion and current leakage all increase with increased humidity levels; so moisture-resistant adhesives provide multiple ways of shielding PCBs from damage: potting/encapsulation/conformal coating/underfilling are just a few examples that prevent moisture entry into components.
Selecting moisture-proof adhesives when manufacturing electronic components is of great significance in ensuring their longevities and peak performances. Electronic adhesives seal circuits from environmental moisture intrusion, providing reliable performance across a range of conditions and environments.
- Chemical Resistance
Electronic devices may come into contact with numerous chemicals during manufacturing, installation and maintenance processes. Without sufficient chemical resistance coating to shield it from external substances like detergents and cleaning fluids, their exposure could wreak havoc with performance as well as cause short circuits.
Chemical resistance should be one of your criteria when selecting adhesives for electronics devices. Chemical-resistant glue can withstand exposure to harsh substances without losing its bonding properties – thus keeping devices safer than ever.
Electronic components can often be exposed to high temperatures during their manufacture and daily operation, from processes such as soldering during assembly or electrical resistance, which may overheat devices during daily work life and cause their adhesive bonds to either melt away completely or lose strength, potentially damaging components within. Adhesives without high temperature resistance could potentially melt under such stress causing irreparable harm to components within an electronics component.
One and two part epoxies, sodium silicate glues and silicone-based adhesives are ideal choices for high temperature applications in electronics. Selecting high temperature adhesives that have been designed specifically to withstand high temperatures will increase device lifespan while being safer and cost-efficient in the long run.
Conclusion Adhesives used for bonding, coating and encapsulating electronic components play an integral part of electronic device performance, reliability and longevity. Selecting an ideal adhesive is of great significance in electronics industries – use these points as a checklist when selecting electrical adhesives based on your electrical adhesives needs and consideration of specific questions that help choose one with properties suitable to your application needs.
Selecting an adhesive with care will provide your device with mechanical and chemical stability as well as reliable safety, prolong product lifespan and reduce device failure – ultimately improving customer satisfaction and increasing sales.
RW offers high-performance adhesives designed specifically to meet electronics industry requirements – with various mechanical and chemical properties tailored specifically for each industry sector. Give us a call now for more details!
