Frequently Asked Questions

DELO offers various curing methods for different application requirements.

• UV curing
• Heat curing
• Dual curing
• Anaerobic curing

Light-curing adhesives can cure in just a few seconds with optimal exposure. The curing time depends on the individual adhesive, component, and process.

Adhesive can be dispensed in many different ways. It can be dispensed automatically, semi-automatically, or manually. The quantities and application methods can also vary greatly, from individual microgram droplets to beads or potting applications in the gram range. Dispensing can be done through a dispensing needle on contact, with a jet system contactlessly, or through other special application methods such as screen printing etc.

The concrete dispensing requirements should be at the center of all considerations regarding adhesive dispensing. These can arise from the requirements of the finished product, the production process, or the choice of adhesive. To help customers maintain an overview in this broad and complex field, DELO provides comprehensive consulting and support with extensive and long-standing experience. In addition, practical investigations with various dispensing methods are regularly conducted in DELO's test laboratories.

As a system provider, DELO also offers its own dispensing systems, ensuring customers receive the optimal combination of adhesive and dispensing system for their specific application. A detailed overview of the various dispensing methods can be found in our Academy.

Dispensing processes

Yes - there are 1C adhesives with very low curing temperatures. These are frequently used to protect temperature-sensitive components or to save energy in the production process. The lowest curing temperature for the DELO MONOPOX VLT series (VLT = "Very Low Temperature") is possible at just +60°C. Some KATIOBOND adhesives also have a low curing temperature and can cure from +80°C.

Light-curing adhesives offer decisive advantages for modern production processes:

Time savings:

• Curing possible in seconds
• Increased productivity through short cycle times
• Rapid handling strength for immediate further processing

Process optimization:

• Good automation capability in production
• Precise control of the curing process

Material protection:

• No heat exposure during curing
• Protection of temperature-sensitive substrates

Optical properties:

• Transparent bonding possible
• Preservation of optical quality

Energy efficiency:

• Energy-saving by eliminating oven heating
• Reduced operating costs

Yes, DELO has developed various dual-curing technologies that combine multiple curing mechanisms in one adhesive (DELO DUALBOND).

Advantages:

• Flexibility in curing depending on component geometry
• Optimal curing even in hard-to-reach areas

Container sizes vary by product and can be found in the respective technical data sheets. In general, DELO offers various container sizes:

10ml cartridges, 50ml cartridges, 160ml cartridges, 6oz cartridges, 50ml and 200ml dual-chamber cartridges, 310ml Euro cartridges, 600ml cartridges, 20oz cartridges, 1000ml bottles, 5l buckets, canisters, drums, hobbocks

The standard continuous operating temperature range for many applications is -40 °C to +125 °C. The highest continuous operating temperature range is -55 °C to +220 °C.

The curing temperature also varies depending on the application and requirements. For example, the curing temperature of products in the DELO MONOPOX portfolio ranges from +60 °C – suitable for temperature-sensitive assemblies – up to +150 °C, to achieve particularly resistant bonds.

Proper storage is crucial for the quality and shelf life of your DELO adhesives:

• Store adhesive in unopened original containers
• Use light-proof packaging
• Ensure dry storage
• Avoid direct sunlight
• Observe storage temperatures according to product data sheet
• Follow manufacturer specifications for shelf life

There are various dispensing techniques:

• Time-pressure dispensing (control via time and pressure)
• Volumetric dispensing (exact volume control for highest precision)
• Jet dispensing (contactless adhesive application)
• Activation on the Flow

No – all DELO adhesives are completely solvent-free.

Solvents are volatile chemical compounds used in some adhesives to reduce viscosity and facilitate processing. After application, they evaporate, causing the adhesive to cure. While this may sound convenient, it comes with significant drawbacks: solvents are often harmful, irritating or even toxic – and their vapours can be explosive at certain concentrations.

At DELO, we deliberately avoid the use of solvents in our adhesives. This means:

• Increased workplace safety
• No risk of explosion
• More environmentally friendly processing

Yes, DELO offers specialized adhesives for sealing. Sealing solutions are frequently used in electronics or automotive applications.

Yes, DELO adhesives are waterproof. DELO adhesives show very low water absorption. Some adhesives in the DELO PHOTOBOND series were specially developed as sealants and are even watertight. In consumer electronics applications, e.g., with wearables, sealing against water, moisture, and dust is often critical.

Media resistance describes the ability of an adhesive to maintain its properties even when in contact with various liquids or gases – such as fuels, oils, coolants or cleaning agents – without swelling, dissolving or losing strength.

DELO adhesives are media resistant and demonstrate excellent resistance to a wide range of chemicals and operating media. The media resistance of an adhesive generally depends on the degree of crosslinking of the polymer. The more strongly the polymer chains are crosslinked, the less moisture and media can penetrate the adhesive.

Yes, DELO has a portfolio of transparent adhesives for various applications. The main product lines for transparent adhesives are DELO PHOTOBOND and DELO KATIOBOND.

Yes, there are various DELO adhesives that have been developed for applications with low CTE (Coefficient of Thermal Expansion). A soft adhesive provides stress relief. A low CTE of the adhesive is used to induce fewer stresses itself in combination with a low-CTE substrate (e.g., minimize warpage) or, for example, to keep the quality of an optical system as consistently high as possible during temperature changes (lens shape change due to CTE).

The temperature-dependent changes in mechanical properties of adhesives have physical and chemical factors:

• Thermal activation of molecular movement
• Breaking of weak bonds with increasing temperature
• Changes in chain conformation and mobility
• Different thermal expansion of adhesive and substrate

Yes, the choice of lamp is critical for complete and rapid light-curing of adhesives. Both the wavelength and intensity must match the specifications in the technical data sheet.

View DELO UV lamps

In direct dispensing, the cartridge is pressurized with compressed air to dispense adhesive. Subsequently, the pressure is released again to stop dispensing. With dispensing valves like the DELO-DOT RE, pressure is permanently applied to the cartridge, as the valve controls the adhesive flow. For dispensing, the valve is opened and closed again after dispensing is complete.

Using a dispensing valve brings several advantages over direct dispensing. Due to the constant pressure on the cartridge, typically no air or less air accumulates under the piston in the adhesive cartridge. This makes dispensing generally more reproducible over the entire fill volume, and air bubbles in the dispensed adhesive caused by pulsed control do not occur. At the same time, the cartridge fill level has a significantly lower impact on the dispensed amount when dosing through a valve, since the air space in the cartridge does not need to be constantly refilled and vented. Additionally, the direct opening and closing of the valve often enables more precise dosing amount adjustment.

On the other hand, there is additional effort for cleaning and maintenance of a dosing system. And even though the DELO-DOT RE dispensing valve is very small, the additional space requirement must still be considered in the mechanical design of the dispensing station.

 Further information on dispensing valves and their applications can be found here:

Dispensing Valves

Volumetric dispensing systems work with a displacement principle, where a defined volume is delivered during dispensing. The repeatability is thus virtually independent of adhesive supply pressure and adhesive temperature. Volumetric dispensers like the DELO-DIV VD, which are manufactured with tight tolerances, therefore offer a simple way to meet the highest demands for dispensing reproducibility.

Additionally, many dispensers can prevent dripping by reversing the dispensing motion. This option is available as standard in the DELO-DIV at the end of a dispensing cycle, for example.

Further information on adhesive dispensing systems can be found here:

Adhesive Dispensing Systems

No, the wavelength of the lamp must match the adhesive and the radiation intensity must be sufficiently high. Therefore, DELO offers professional LED lamps with either 365 nm, 400 nm, or 460 nm wavelength.

DELO UV lamps

LED technology enables significantly longer lifespans, can be controlled much better in terms of intensity, and the limitation of the narrow wavelength range that is emitted is also a major advantage, since almost all the radiated energy is used for curing the adhesive.

DELO UV lamps

Yes, with the right pretreatment, everything can be bonded.

• For Teflon: Corona or low-pressure plasma
• For PP: Plasma, flame treatment, gas phase fluorination, primer

Often, several pre-treatment methods are suitable – which one is most appropriate depends primarily on the process:

• Small quantities: A primer is a simple and cost-effective solution.
• Large quantities with large surfaces: Flame treatment or corona are the preferred options.
• Large quantities with smaller surfaces or line shapes: Atmospheric pressure plasma is often a good choice here.

The application areas of the different methods partially overlap, and there are also special variants available depending on specific requirements.

 Further information on bonding different materials can be found here:

Materials

The main purpose of adhesives is connecting and fixing components. Functional materials additionally offer special functional properties, such as electrical conductivity or thermal conductivity.

View functional materials

Yes, adhesives can conduct heat. Thermal conductivity is an important functional property for many applications such as die-attach (chip bonding) or electronics applications.

Currently, DELO does not offer explicitly biobased adhesives. Instead, DELO pursues an approach of maximum efficiency and pollutant avoidance. The raw materials used are solvent-free, low-outgassing, and pollutant-reduced.

However, some DELO products do use biobased raw materials such as raw materials based on cashew nut shell oil. Furthermore, we test our in-house developments and collaborate with technology leaders to evaluate sustainably available raw materials on the market for their use in our adhesives.

For light curing of adhesives, light dose as well as intensity and exposure time are individually relevant. To achieve complete curing, the minimum exposure dose (minimum energy amount) must be observed, the recommended intensity range must be maintained, and the minimum exposure time must not be undercut. These three parameters depend on the adhesive geometry (such as layer thickness) and component characteristics (including reflective surfaces and heat sink effects in chip bonding).

Yes, there are solution approaches for bonding non-transmissive substrates. One possibility is pre-activation. Here, the adhesive is exposed to light before joining, and curing can then take place even in shadow zones without further exposure. Another possibility is dual-curing adhesives, which cure through a combination of light + heat, for example.

There are various internationally recognized approvals and standards for adhesives that are relevant depending on the application area.

• Electronics: IPC/JEDEC, IEC
• Medical: ISO 10993, USP Class VI
• Aerospace: CS/FAR, ASTM E595, ECSS-Q-70-02
• Automotive: Automotive Grade, specific OEM standards
• General: UL Standards, RoHS, REACH, VOC limits, DIN 2304

Yes, DELO offers drop-resistant adhesives for applications that must withstand drop impact loads.

Yes, DELO offers yellowing-stable adhesives. The main application areas for these adhesives are optical applications (e.g., active alignment of optics, bonding of optical components) and electronics applications (e.g., gap sealing and housing sealing).

Yes, DELO offers specifically adjusted refractive indices for various optical applications. The refractive indices can be varied across a broad spectrum.

Yes. The main application areas for these adhesives are sealing & encapsulation of optical systems and electronics protection of light-sensitive components and sensors.

Automated adhesive application control is a quality assurance process used in industrial production. It ensures that the adhesive has been applied in the right place, in the right quantity and without any gaps or missing areas.

One proven method for this is the use of fluorescent dyes in the adhesive. Under UV light, the applied adhesive becomes visible and can be automatically inspected by camera systems. This enables reliable and fast inspection directly in the production process – without additional process steps or manual checking.

Automated adhesive application control at DELO enables precise, reproducible and fully monitored adhesive processes in modern production environments.

Adhesives fluoresce for specific application reasons - this is a deliberately adjusted property for quality control and process monitoring. The main purpose is visibility control during dispensing - dispensing errors or uneven application can be detected immediately, leading to increased process reliability. The fluorescence is therefore not a side effect, but a targeted functionality to improve process reliability and quality control in industrial adhesive applications.

Yes, DELO has a product line for damper adhesives. These are mainly used in loudspeaker manufacturing. Adhesives with damping properties have high vibration and oscillation damping, can absorb dynamic forces well, and can compensate for stress peaks.

Yes, there are reflow-resistant adhesives that can withstand the high temperatures of soldering processes. The reflow soldering process reaches peak temperatures of up to 260°C and places extreme demands on adhesives in electronics manufacturing. Typical applications are die attach applications, dam & fill applications, or advanced packaging bonding applications.
Reflow-resistant adhesives have a high glass transition temperature, low thermal expansion, are highly chemically cross-linked, and have a thermostable polymer base.

Yes, cured adhesives can absorb water. The media resistance of an adhesive typically depends on the degree of cross-linking of the polymer. The more strongly the polymer chains are cross-linked, the less moisture and media can penetrate into the adhesive.
Water absorption can lead to reduced mechanical strength, swelling, possible adhesion loss, or impairment of long-term stability.
Strategies to minimize water absorption can be implemented through proper adhesive selection and application optimization. Heat-curing epoxies, for example, have a higher degree of cross-linking and thus absorb less water. Additionally, complete curing should be ensured and an optimal curing temperature should be used.

DELO offers adhesives that achieve good strength even on difficult-to-bond surfaces such as LCP, PPS, zinc die-cast, or aluminum and enable reliable bonds.

DELO is an international company with locations in Germany (headquarters), the USA, China, and Singapore. Additionally, we have a global sales team and local distributors in various regions.

Delivery Options:

We cannot provide a complete list of all countries we can deliver to, as each shipment is individually assessed. Export possibilities depend on various factors/assessment criteria:

• Third-country exports are evaluated separately and individually
• Dual-use goods (products with potential military applications) are subject to special control regulations
• US EAR regulations (Export Administration Regulations) must be complied with
• Embargo countries are reviewed according to current international sanctions lists

Do you have a specific delivery inquiry? Please feel free to contact our sales team or your local representative. We will individually assess whether and under what conditions delivery to your desired destination country is possible.

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The processing time is 4-5 weeks from the respective arrival date at DELO. Please note that your device should arrive at one of the specified dates - devices that arrive later will only be considered in the next calibration period.
 

Further information and current dates can be found here: DELOLUXcontrol

We recommend annual calibration of your DELOLUXcontrol measuring device to ensure consistent quality of your production process.
 

Further information and current dates can be found here:

DELOLUXcontrol

When receiving goods, you should observe the following points:

• Immediate inspection: Check delivery and packaging immediately for completeness and transport damage
• Temperature-sensitive adhesives: Cooled DELO adhesives must be stored immediately upon arrival according to the storage instructions on the product label - do not leave at room temperature longer than necessary
• Documentation: Check delivery notes and product labels for correspondence with your order
• Storage: Observe the specific storage conditions and temperature ranges on the product label
• Claims: Report damage or deviations immediately to the freight forwarder and to DELO

Do not interrupt the cold chain for temperature-critical products - this can impair product quality.

Watch the video to lern how to handle temperature sensitive adhesives.

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