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Bonding SensorsBonding Sensors

Contents

2 | DELO-News

Transmitter for Field Use Georg Fischer relies on DELO

Bonding SensorsThe right adhesive for every sensor

No More HeatDual-curing adhesives achieve

fi nal strength at +60 °C

4

12

8

The Age of BondingBooming revenues

11

Editorial

DELO-News | 3

Adhesive-friendly Design Tips & tricks for engineers, part 2

Light-fi xed Hybrid Adhesive

High performance even in aggressive media

9

14

Dear readers

Everyone is talking about autonomous driving. It is however true to say, and this despite the remarkable progress already being made today, that it will take another few years before we see the fi rst fully autonomous series production vehicle on the road. Nonetheless, in view of the enormous gains in safety and comfort, this will occur sooner rather than later.

As well as cameras, it is sensors that play a key role in providing the autopilot with information of decisive importance. Of course, sensors are not something that exist only in the future: for a long time now they have been performing important functions. In our title story, we are therefore introducing fi ve typical sensors and we provide tips about which group of adhesives, the view of the different requirements profi les, is most suitable for the respective adhesive, sealing or molding tasks, and how they can be used to effect processes rapidly.

With regard to cars: The best way to reach our head offi ce in Windach near the idyllic lake Ammersee is on four wheels, for example at the wheel of a BMW i8. All readers who have not yet visited us will gain an impression in our new company fi lm of what working life looks like here at DELO, and of what we understand cooperation to mean. You will also gain an impression of what is so very special about the BMW i8 (https://www.youtube.com/user/DELOadhesives).

Now enjoy having a good read!

Sabine Herold, Managing Partner

ImprintDELO Industrial Adhesives, DELO-Allee 1, 86949 Windach, GermanyPhone +49 8193 9900-0, marcom@DELO.de, www.DELO-adhesives.com/en

4 | DELO-News

Cover Story

Bonding Sensorsin Carsin Cars

Sensors can generally be found anywhere in the car where physical variables such as temperature, pressure, position, or speed have to be captured.

Because these signals are then passed on to control units and evaluation electronics via interfaces, the sensors must be reliably sealed against any aggressive media. Sensors that are used in harsh environmental conditions, e. g. for monitoring the oil level or pressure, must be composed of

dependable materials. Encapsulants and adhesives that are particularly tolerant of high temperatures and have good chemical characteristics are especially suitable for these types of applications.

Let’s look more closely at parking distance, tire pressure, speed, position, and engine steering sensors as well as suitable adhesives.

Safe Parking Made Easy

When it comes to parking distance sensors, it is essential that the driver be able to depend on the accuracy of the data. This is because sensors help the driver safely maneuver their car into small parking spaces. If the sensor fails, it can be very expensive for the driver. So it is particularly important that the adhesive used has good acoustic characteristics such as the right oscillation behavior in addition to mechanical functionality, so that the ultrasonic signal is transmitted unadulterated and in high-quality. Due to their position in the bumper, the temperature requirements are moderate. The adhesives should be usable in a temperature range from – 40 °C to +85 °C. In addition, they have to pass special automotive tests, such as temperature and salt spray tests.

Light-curing DELO KATIOBOND epoxy resins meet exactly these requirements and allow for in-line processes and short cycle times in series production, while allowing reliable curing of shadowed areas by preactivation. In view of the continuously increasing demand, ultrasonic sensor manufacturers can effi ciently produce high volumes.

Installed in many new cars: Parking distance sensors

DELO-News | 5

Cover Story

These days, up to a hundred sensors may be used in one vehicle, a trend that continues to grow. They have a variety of functions, including safety, convenience, and in the powertrain. Many of these sensors have components that are fi xed with adhesives and protected with encapsulants. Requirements are particularly demanding in vehicles and the adhesives need to work reliably for long periods of time in challenging surroundings like the engine compartment. DELO provides some tips on which type of adhesive is most appropriate for which sensor.

Tire pressure monitoring sensors have been legally required for some time now

Under Pressure

Sensors are also used as alarm triggers as soon as the tire pressure drops. They are therefore very important with respect to safety, fuel effi ciency, and wear. The incorrect tire pressure can create a huge risk of having an accident by signifi cantly extending the braking distance or negatively impacting stability when cornering.

For die attach, sealing and fi xing tasks, heat-curing DELO MONOPOX epoxy resins are preferably used, while 2C materials of the DELO-DUOPOX series are used for large-volume PCB casting. They all have in common that they are especially media-resistant and repellant against typical automotive fl uids. In particular, they can withstand salt spray and cleaners. They also provide impressive results in thermal shock, humidity storage, vibration and drop tests. In order to ensure that pressure measurement always works correctly, the tightness of the sensor fi xation to the housing is checked with a typical pressure of 7 bar for the long term and 9.5 bar for the short term.

Cover Story

6 | DELO-News

Finding the Right Balance

Hall sensors are always applicable when position or speed need to be captured. These sensors are sometimes located directly on the wheel rim, or even on the wheel hub. From there, they provide accurate information on how frequently the wheel is rotating. For their assembly, dual-curing (light- / anaerobic-curing) adhesives are especially appropriate because they enable a rapid prefi xation of the magnet, the magnet retainer and the Hall sensor. In addition, they secure fi nal curing, even in shadowed areas. The adhesives are also highly resistant to media impacts like oil, gas, or even braking fl uid, and also pass salt spray tests, refl ow tests (JEDEC), vibration tests, and drop tests with fl ying colors.

A Hall sensor measures rotation, among other things

Cover Story

DELO-News | 7

Just the Right Mix

Mass air-fl ow and TMAP sensors help reduce emissions and are located in the engine compartment, or more precisely in the air intake system. The mass air-fl ow sensor, MAF for short, has the primary task of communicating the incoming air mass to the engine control unit. This quantity is needed in both gas and diesel engines to calculate various parameters. Mass air-fl ow sensors are somewhat more precise than TMAP sensors. A TMAP sensor measures the pressure and the intake temperature and can use this data to determine air mass.

In order to protect sensors, extremely reliable epoxy resins of the DELO MONOPOX and DELO-DUOPOX portfolio are used that pass all the typical automotive tests. They are resistant to oil, gas, and braking fl uid and can survive in a temperature range of – 40 °C to +155 °C. Even when stored at these temperatures, the encapsulant on the sensor does not display any stress cracks. There is also no interaction between the transmission oil and encapsulant.

Conclusion As shown by the examples, the optimum adhesive depends very heavily on the thermal, mechanical, and chemical requirements of the sensor. There are even appropriate adhesives and encapsulants for the high-reliability sector that enable durable functionality under the most severe environmental conditions.

TMAP sensors are exposed to the most severe environmental conditions

Important for exhaust control: Mass air-fl ow sensors have become

a topic of interest only recently

Product

8 | DELO-News

Fast Curing Without Heat!Dual-Curing Adhesives – Full Strength at Only +60 °C

DELO has developed new DELO DUALBOND adhesives that reach full strength at only +60 °C after prefi xation by light. The new range is completed by DELO MONOPOX adhesives curing in a single step at low temperatures, three times faster than previous products. These epoxy resin-based adhesives are mainly used in electronics.

The new dual-curing adhesives can be prefi xed after only half a second of exposure to light. Prefi xing is particularly advantageous in the case of production

lines, since, after dispensing and fi xation, the component will be directly transferred to the next step of the process chain. This guarantees reproducibility and fast production, avoiding incidents like the slipping of individual components. Products of the DELO DUALBOND family also feature excellent adhesion to LCP and allow adjustment of the adhesive properties ranging from fl exible to hard (elongation at tear up to 70 %).

Fast, Faster, the Fastest – Very Low Temperature Curing

The low curing temperature of these new adhesives reduces the thermal stress between the materials, thus limiting the stress on the component. In addition to that, they allow processing of temperature-sensitive substrates without diffi culty: higher temperatures would only damage the sensitive components.

For purely low-temperature-curing DELO MONOPOX adhesives, it only takes 30 minutes and a temperature of +60 °C to achieve their fi nal strength. This makes them the fastest of their kind. So far, standard products have generally taken 90 minutes at the same temperature to achieve full strength. And still they are able to maintain their favorable properties such as their good adhesion to plastics like LCP, PA, and PPS or their fl exibility on the component.

The adhesives are particularly suitable for temperature-sensitive components such as cameras and

show good adhesion to LCP

Product

DELO-News | 9

Greater Bonding Accuracy, Defined EncapsulationDual-Curing Adhesive for High-Performance Applications

A new hybrid adhesive for the automotive and electronics industry was recently announced by DELO – an epoxy resin that is light-fi xable for the high-reliability sector.

Particularly resistant epoxy resin adhesives with special hardeners are used where bonded or encapsulated components are exposed to extreme temperatures

and aggressive chemicals. However, only heat-curing variants have been available up to now.By contrast, the light curing of the newly developed product offers greater bonding accuracy, a defi ned fi llet, and easier handling of the cured components. What’s more, in the case of glob top encapsulation, it forms a skin and can “freeze” its shape, so does not fl ow away during heat curing. This means that a defi ned glob top encapsulation is possible even if miniaturization makes space tight on the circuit board, which saves one process step compared to the alternative Dam & Fill method.

Top Performance Even in Aggressive Media Like Oil or Printing Inks

In a two-stage curing process, the adhesive is fi rst light-cured in 1 – 5 seconds, depending on intensity, and

achieves a die shear strength of more than 1 N on the FR4 circuit board material. Heat curing is required, for example 30 minutes at +150 °C, after which the full strength of 50 MPa on FR4 is attained.The dual-curing product has universal adhesion and is available in viscosities for bonding applications as well as for encapsulation. Both variants are easy to work with thanks to their thixotropic fl ow characteristics. Their temperature range of use extends from – 65 °C to +180 °C. For even higher thermal requirements, DELO has recently introduced high-temperature adhesives to the market, which are temperature-resistant up to +250 °C.

Despite its hybrid nature, the epoxy resin is highly resistant to chemicals. Even after 500 hours stored in aggressive media, like transmission fl uid, gasoline, or methanol, there is hardly any effect on its mechanical properties. The product also exhibits good resistance to printing inks, which attack most adhesives. It is therefore particularly suitable for adhesive applications in the print head that require highly accurate positioning.

10 | DELO-News

Product

Adhesives Light the WayAdhesives Light the WayLED-Compatible Materials for Light Engines

14 DELO adhesives were tested and released for use in LED lighting. Ten products have received approval for direct LED contact, and an additional four were certifi ed for indirect contact. They allow for durable, high-intensity LED modules and light engines.

The fourteen adhesives demonstrated their chemical tolerance in tests standard for the LED industry. The modules were supplied with 700 mA for six weeks, which heated them

to up to +70 °C. During the subsequent intensity test, there was no decrease in brightness for the products meant for direct LED contact, and for those with indirect contact only a very slight decrease. The low-outgassing and yellowing-resistant adhesives ensure the long-term high optical quality of the LED module.

DELO predominantly uses light-curing epoxy resins for its LED-compatible products. Compared with silicones, they are more stable and provide a better seal. Under some circumstances, humidity can enter the LED and electronics when silicones are used, which shortens their service life. Light curing of epoxy resins and acrylates is also faster, making them more effi cient to produce. Their temperature stability and fl exibility means that they can withstand extreme heat, cold, and even vibrations. Their universal adhesion also allows reliable and practically invisible connections of even the most complex geometries and material combinations.

Precisely attaching a lens is an important step on the path towards a high-performance light.

Market

DELO-News | 11

Global Adhesive Market Expected to Reach $ 60 BillionThe 21st century is said to be the age of adhesive bonding. The extent to which bonding is booming is illustrated by three recent market reports.

According to the global research fi rm MarketsandMarkets, the adhesives and sealants market, along with its applications, has witnessed a high growth for the past

few years and this growth is estimated to increase in the coming years. Its global market value is projected to reach USD 60 billion by 2020, growing at a CAGR of 4.7 % between 2015 and 2020.

Growth in the Asia Pacifi c region is expected to outpace that of both the US and Europe. Asia Pacifi c growth is forecast to be about 6.2 % during the period as more manufacturing is shifted to that region.

As these numbers do not only include reactive systems such as DELO’s high-performance products for demanding electronic and automotive applications, but also water- and solvent-based adhesives used for construction and furniture as well as hotmelts, it’s worth taking a closer look at different chemical types and industries.

Epoxies with Strong Increase

The market size of epoxy adhesives, in terms of value, is estimated at USD 1.7 billion in 2015 and is projected to

reach USD 2.3 billion by 2020, registering a CAGR of 6.3 % between 2015 and 2020. The major driver is the growing wind energy, transportation and automotive industries, particularly the increasing use of composite materials and multi-materials designs, massively contributing to lightweight and fuel effi cient vehicles.

Electronic Adhesives Doubling Market Size

In their report on the electronic adhesive market, Grand View Research projected their outlook even further. While they estimated the market size at USD 3.3 billion in 2014, they expect it to more than double it until 2022, reaching USD 7.8 Billion with a CAGR of 10.6 % by then.

UV-curing adhesives are anticipated to be the fastest growing product segment over the next seven years on account of rising demand for large volume and short cycle time assembly. This particular segment is expected to growth at a CAGR of over 12 % from 2015 to 2022. No matter where you look, bonding is becoming more and more important.

$ 59.75 billion

$ 2.25 billion

$ 7.80 billion4.72 %

annual growth rate

6.3 %annual growth rate

10.6 %annual growth rate

Global adhesive market

Epoxy resins Electronic adhesives

$ 47.45 billion

$ 1.66 billion

$ 3.28 billion

12 | DELO-News

Case Study

Transmitter for Field UseGeorg Fischer Chooses Display Adhesive made by DELO

Electronic equipment for fl uid and gas pipes has to be extremely resistant to adverse conditions. Georg Fischer has chosen to use DELO DUALBOND display adhesive for a transmitter with a particularly large display.

In addition to meeting all the optical requirements, it also enables an effi cient production process.

Many pipelines are exposed to the elements and must face tough environmental conditions, including humidity, temperature variations, heavy

frosts in winter, or long hot spells in summer. It goes without saying that the electronic equipment also has to face these same demands. Georg Fischer has fi rst-hand experience of these challenges. This enterprise is offering plastic and metal pipe systems and associated system solutions for the safe transport of gas and water. Its product portfolio for industry, utilities, and building technology comprises fi ttings, valves, pipes, automation, and connection technologies.

One product from the company’s control systems range is the Signet 9900 Transmitter, a device used to measure and monitor fl uid and gas media through a

single-channel interface for sensors such as fl ow, pH / ORP, conductivity / resistance, pressure, temperature, fi lling level, and salinity. It can be integrated into a control cabinet or installed in the fi eld, and is used for many other applications in addition to media fi ltration, wastewater treatment, and chemical production.

What makes the transmitter stand out is its extremely large display. Thanks to the transmitter display's generous dimensions of 99 mm × 99 mm, information can be read at up to four or fi ve times the distance compared with conventional transmitters, reducing the risk of incorrect readings or misinterpretation of the displayed values.

Display Bonding Considerably Improves Readability

Good readability is not just the result of a backlit display – bonding the display also helps. In this process, a glass cover is bonded onto an LCD module (LCM) using optically clear adhesive. It’s refractive index is adapted so that light refl ections can be reduced by up to two thirds. At the same time, the shock resistance of the display massively increases, because it is more stable in the event of shocks and falls.

There was no question of Georg Fischer using tape for display bonding, since it has inadequate humidity resistance. Instead, the company initially chose a two-component adhesive that in principle met the optical requirements. However, Georg Fischer were looking to establish a more stable and faster production process. With two-component adhesives, air bubbles frequently form, even if the two components are mixed accurately. These bubbles can be time-consuming to remove, and may even result in the unit being scrapped. The pipe system provider also felt that speed was even more of an issue: The complete bonding process, starting with mixing, took too long and led to excessively high storage costs in relation to the transmitter quantities required.

The 9900 Transmitter for pipe systems from Georg Fischer has a particularly large display

DELO-News | 13

Case Study

As well as conducting joint tests, good project management should also include working with the customer to defi ne the production process and all its curing parameters, and offering advice on choosing the right equipment.”

Light Curing Accelerates Production Process

That is why Georg Fischer contacted DELO, which suggestedusing 1C optically clear adhesives. They can be dispensed without bubbles and also cure in seconds under high-energy light, so that the displays can be handled immediately. One benefi t is that the adhesive also cures in shadowed areas, where light cannot reach, through contact with humidity present in the air. This ensures that no fl uid adhesive remains.

Thorough Testing

First it was necessary to check that the material developed for this application, DELO DUALBOND OC4922, met the specifi ed properties. So, Georg Fischer and DELO subjected the bonded sample to three demanding industry-standard tests: A UV test acc. to ASTM G154, a simulation of outdoor weather conditions acc. to ISO 4892-2, and heat / humidity cycling from –15 °C through +70 °C. The adhesive met the optical requirements in all tests. The b value remained at an excellent level for the yellowness, meaning that Georg Fischer could be sure that the adhesive does not become perceptibly yellow. “It was the extensive reports and research conducted by DELO that instilled confi dence in this new option”, said

Gert Burkhardt, Vice President Operations, Georg Fischer, explaining their product choice.

But for DELO, the project did not end there. “In line with our philosophy, an adhesive manufacturer should do more than just recommend an adhesive, provide samples, and then send an invoice”, said Robert Saller, Director of International Sales. “Good project management should also include working with the customer to defi ne the production process, and offering advice on choosing the right equipment.”

Georg Fischer opted for the DELOLUX 20 area lamp, which is also produced by DELO and is perfectly suited to the adhesive. The LED lamp has a wavelength of 400 nm and cures the material at a low intensity within 60 seconds. However, the valve of another manufacturer was suitable for dispensing the adhesive, so its use was also recommended.

“It is an exciting time as we look to move forward with the process that will address long-standing issues in our optical bonding”, Mr. Burkhardt added.

With the defi nition of the process completed, Georg Fischer were able to forge ahead with the ramp-up phase, integrate the adhesive into production, and gradually increase the volumes. After such great collaboration and the successful completion of this project for the display, the two companies want to tackle a new application together in the future. But all they will say for now is that it too involves tough requirements for the adhesive to cope with.

14 | DELO-News

Tips & Tricks

Structural bonding has many advantages over conventional joining technologies. However, adhesives should be considered early on in the design phase to take full advantage of their potential. The fi rst part of this article (edition: fall 2015) was about how to ideally utilize these possibilities with a tongue and groove connection. The second and last part introduces further design options.

While tongue and groove is a reliable and widely used method to ensure solid structural bonding, it is not feasible when bonding thin metal sheets.

However, there are several other options available. If the materials are formable, bending the components and placing them one on top of the other will improve the bond strength, as this will signifi cantly increase the bonding area. Although more complex, as it involves additional process steps, this is an excellent option where higher strength is required (fi gure 1).

Fig. 1: Bending is another design

The strength of a pipe joint leaves much to be desired if the two components are bonded at their ends (fi gure 2). Adding an additional interior or exterior ring enlarges the bonding area tremendously and decreases the risk of bending stress. The two components can also be overlapped by adapting the diameter of one. Because of the adhesive’s sealing properties, liquids can easily fl ow through these pipe joints without leaking.

Fig. 2: The bonding area of a pipe joint should be increased, while edge-to-edge joins should be avoided

Simple Steps for Adhesion SuccessSimple Steps for Adhesion Success

A correctly dimensioned bonding gap is extremely important when engineering an adhesive-friendly design. It ensures a consistent adhesive layer thickness, which enables the adhesive to fully develop its adhesion forces.

It can be provided by a defi ned contact area with spacers integrated into the components being bonded, or by a tongue and groove joint. If the gap is too narrow, the components press the adhesive out and the bond will not hold.

Part 2

DELO-News | 15

Tips & Tricks

Conclusion In order to create an adhesive-friendly design, engineers should follow basic design principles such as working with suffi ciently large bonding areas and eliminating the potential of peel and bending stress. By following these steps the end result will be a strong, sturdy and powerful joint.

Advantages of bondingAdvantages of bonding

Different materials can be joined Tension is evenly distributed Components are not weakened, e. g. by boreholes High resistance to dynamic forces Laminar joining of thin components Components are not or are only slightly subjected to heat Simultaneous bonding and sealing is possible The adhesive layer balances tolerances Electrically or thermally conductive adhesives are available

8 rules for design engineers8 rules for design engineers

Provide suffi ciently large bonding areas and gaps Achieve evenly distributed tensions Limit stress to compression, tension and shear stress if

possible Avoid peel and bending stress Avoid eccentric force transmission Prevent plastic component deformation Provide adhesive-friendly surfaces Comply with the curing conditions required by the adhesive

Trend

16 | DELO-News

With LeanVDS, Scheugenpfl ug supplies an entry-level vacuum casting machine

Good-bye Air BubblesWhen manufacturing electronic components it is important to protect the components against future external infl uences. Most manufacturers use casting or fi lling to do so. Especially for high-performance applications vacuum dispensing is the method of choice. A high number of manufacturers are already using this highly effi cient type of dispensing. Others have not tried it yet, because they consider it too complex or shy away from the supposedly high up-front investment. A compilation of best-practice tips will show that vacuum dispensing is not rocket science. Perhaps now even the most skeptical engineer will want to give this method a try at last.

Automotive, industrial or consumer electronics: in all applications electronic components such as chips or entire PCBs must be protected against mechanical

or chemical stress. One typical example are motor control sensors such as exhaust sensors or components that get in contact with hot gearbox oil. Other applications

involve unprotected wire coils and the enameled copper wires of wire coiled components.

Depending on their usage, any one of these components may be exposed to considerable stress in terms of corrosion, vibrations, moisture or high voltage. Since injection molding is a highly complex production technique and production costs of the molds are considerable, most manufacturers

choose casting or fi lling for their production environment.

Conventional metering and dispensing methods, however, often do not cover all requirements. For example, the tiny gaps between coiled wires may trap bubbles of air, which break the insulating cover and diminish or even ruin high-voltage resistivity. Air bubbles caught below printed circuit boards expand when heated – by several mm if the geometry so allows – which causes tensile loads to act on the coating and on the PCB. In this case, high voltage surges may rupture the coating even if fl exible and voltage resistant adhesives are used. Aggressive chemicals such as oil may get in contact with the unprotected surface and damage the component.

TheSolutionforDemandingCases

Vacuum dispensing – also suitable for in-line integration – is the method of choice especially in the production of high-performance electronic assemblies as it prevents air from getting caught between component and coating. Vacuum dispensing is not only ideal for expensive

Trend

DELO-News | 17

Cast standard component, transparent for illustration

high-voltage parts and safety-related components, it also handles assemblies with complex geometries, undercuts or extremely narrow gaps.

From a technical point of view the generation of a perfect vacuum, which is entirely void of air, is not required. Vacuum in this context means the reduction in pressure down to approximately 1 mbar. The further the air pressure is reduced, the longer the process takes and the higher are the energy costs involved. Also, not every component can sustain a strong pressure reduction, a fact to bear in mind when applying a vacuum. While wire coiled components are mostly insensitive to atmospheric pressure, air encapsulated within a capacitor can cause the component to burst when exposed to an external vacuum. Therefore, the vacuum level should always be matched to the task at hand.

To guarantee that no bubbles are introduced, the complete preparation, feeding and metering process must be carried out in a vacuum. Then, a process called thin-fi lm degassing performed by a high-end material preparation and processing system removes all traces of dissolved air. An agitator is used to further speed up the degassing process by stirring and circulating the dispensing material. This lets all the contained air rise to the surface of the material where it gets in contact with the surrounding vacuum. The degassing effect occurs at the surface layers of the material. In order to prevent air from re-entering into the material during material reloading all fi ttings, material feed lines, pumps and valves are sealed air-tight.

Comparison Test: Vacuum Dispensing vs. Atmospheric-Pressure Dispensing

We wanted to demonstrate the difference between vacuum and atmospheric-pressure dispensing to manufacturers who still hesitate to try and use vacuum dispensing systems. To do so, DELO Industrial Adhesives and Scheugenpfl ug decided to set up a test system made of standard equipment. We used a conventional PCB in a standard PBT plastic housing as the substrate and a low viscosity two-component, high-performance epoxy resin as the casting resin to simulate a common automotive application. The resin provides long lasting temperature stability up to +200 °C. It is resistant against diesel, gasoline and oil, and protects motor and exhaust control sensors during engine operation.

The test casting under ambient air conditions was carried out with the two components manually mixed and metered.

Trend

18 | DELO-News

Conclusion Depending on the dispensing system used, bubbles can easily form already during preparation, feeding and delivery, or while mixing one- or two-component dispensing masses. By combining the right dispensing material with an all-in-one vacuum dispensing, preparation and feeding system manufacturers have all the instruments they need to increase their components’ reliability to an extent where they comply with all necessary thermal, mechanical, chemical and design requirements.

For the vacuum test run the dispensing material additionally was degassed and then metered and dispensed. To obtain a laboratory-scale setup we used the Scheugenpfl ug LeanVDS system, a typical entry-level model for vacuum dispensing.

This compact-sized system is best suited for R&D applications, for

small batch production and to replace inaccurate

or time-consuming auxiliary processes such as post-evacuation.

In order to analyze the test

Scheugenpfl ug AGGewerbepark 23

93333 Neustadt a. d. Donau, GermanyPhone: +49 9445 9564-0

info@scheugenpfl ug.de

results DELO and Scheugenpfl ug thought it best to use x-ray scans. As opposed to microsections this test method is non-destructive and has the additional benefi t of making sure that no air bubbles are overlooked if the section was made at a position that just happened to be free from bubbles. When comparing the x-ray images of the two components distinct differences immediately became evident. While the PCB on the left was cast bubble-free under vacuum, a large bubble of air had formed under the PCB on the right, which was cast under ambient air conditions. What does that mean? Depending on how the component is used later and on its operating environment the component is very likely to fail – even if this might take several months or sometimes even years.

Process video: Casting of sensors https://youtu.be/N-subr1hwSs

X-ray imaging allows non-destructive verifi cation whether casting was completely free of air bubbles. While the PCB on the left was cast bubble-free under vacuum, a large air bubble formed under the PCB on the right, which was cast under ambient air conditions.

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