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Selective Soldering


Interselect er vores samarbejdspartner inden for selektiv lodning.Vi tilbyder et bredt program indenfor selektiv lodning. Ved at trykke på de forskellige drop down overskrifter nedenunder kan du se information omkring interselect, hvad selektiv lodning egentligt er, samt finde ud af hvilket valg der er bedst for dig

Manual soldering versus selective soldering – InterSelect

Manual soldering: It was once a good technology …

Manual soldering has for good reason outlived its usefulness and has been replaced by selective soldering

Factories are wonderful things when what they produce is shoes or food, for instance, but with manual soldering, however, things look somewhat different. That is associated with the fact that a good solder joint as an electrical or mechanical connection is distinguished by the following features: It works best on startup, it is created at as low a temperature as possible and it is finished as quickly as possible. These assumptions apply to manual soldering and to all other soldering techniques, even if the solder has changed from Sn63/PB37 to lead-free SAC305 or SN100 solder or the like. That a good soldering iron and the relevant skill suffice for manual soldering is a statement that of course still holds true but unfortunately it lost its meaning long ago because manual soldering is simply out of date.

Manual soldering has long been outmoded

Today, manual soldering is no longer used in mass production for reasons of quality assurance. It is no longer even allowed in the automobile industry. Increasing complexity and ever-higher quality standards have contributed to soldering by hand no longer being accepted as an adequate technique. Out of habit, out of the conviction that finishing everything “by hand” is still wonderfully precise, specialists in small service businesses and medium-sized businesses and even some people in big firms still tackle their work manually without knowing that they could make things much easier for themselves, for example with selective soldering.

Manual soldering versus selective soldering:

• The manual technique is suitable only for genuine one-off solutions or for individual repair points.
• The soldering result is only ever as good as the person who produces it. This is and remains the weak point.
• Reproducibility is not guaranteed.
• Extreme flux residues from manual soldering
• Significantly higher localised thermal load because of the small soldering tip and hence only a small contact area
• Manual soldering is not authorised for use in the automobile industry or its supply sector.

Selective soldering secures processes – InterSelect

Selective soldering – when processes should run securely and quickly

Selective soldering with all its advantages is unbeatable in certain circumstances

Among the many advantages of selective soldering, one stands out very clearly from the rest: greater process security and hence reliable reproducibility of soldering results. These are thanks to the technical advantages of selective soldering. In this way, every individual soldering point can be individually programmed and monitored, depending on its ambient conditions, so as to selectively control flux volumes and soldering time. Definitively higher quality can be achieved at significantly lower cost with selective soldering and this can be done with considerable acceleration of the manufacturing process. This makes selective soldering the technology of choice.

The instances in which selective soldering is unbeatable:

With printed circuit boards with SMD’s mounted on both sides, wave soldering is not always possible for wired components. Then the compromise is manual soldering. In the end, wired components cannot be replaced by SMDs, especially not where there are relatively high mechanical loads (connectors, switches). But power electronics also often requires through-hole mounting of the components on to the printed circuit board. So in production there are individual variants that are due to manual intervention (too low or too high temperature) and therefore quality problems are inherent. But these are eliminated by the use of selective soldering.

How does selective soldering work?

Selective soldering always consists of three stages: fluxing (the application of flux), pre-heating and soldering. Even the programming has been perfectly developed so that even people without any prior knowledge can set up a program for selective soldering within minutes thanks to the InterSelect software.

Fluxing with selective soldering

All InterSelect machines have a MicroDrop jet fluxer that ensures fluxing precisely to the drop. And here the fluxer can process both individual points and entire lines (e.g. connector strips) at once.
The volume of flux in every single drop is adjusted to the requirements of each soldering point. Thanks to selective fluxing of the printed circuit board, contamination is minimised and consumption of flux is drastically reduced.
Monitoring of the jet of flux ensures that flux has actually been applied. All the data on this can be read off and processed in the course of operational data recording.

Pre-heating with selective soldering with InterSelect technology

Infrared top and bottom heating:
The pre-heating of assemblies is becoming more and more important, in particular for multilayer printed circuit boards, assemblies for the high energy sector and when soldering with lead-free alloys. Activation of the flux is crucial to proper wetting of the soldering point and therefore for perfect penetration. To avoid stresses on the printed circuit board during pre-heating and in order to achieve optimum heat distribution, the InterSelect infrared emitters are precisely coordinated for selective soldering. The InterSelect parallel systems heat up two printed circuit boards at once, which halves cycle time per printed circuit board. The modular inline units may be equipped with any desired number of pre-heating modules in order to pre-heat additional printed circuit boards in parallel ready for selective soldering. As a result, pre-heating no longer affects cycle time, which often happens with high-volume applications.

The assembly determines output:
The InterSelect pre-heating is automatically adjusted to suit the size of the assembly. Thus for instance the bottom and top heating in selective soldering is provided by several infrared emitters. Only those emitters located directly below or above the assembly are used for the pre-heating. With continuous operation of this type of selective soldering, this leads to considerable energy savings.

Temperature monitoring with a pyrometer:
Conventional pre-heating units work on a time/output basis. Here the pre-heating is provided with a specific heat output over a specific period. Depending on the printed circuit board, this leads to different temperatures on the assembly. The InterSelect units for selective soldering work with a pyrometer control unit by means of which the temperature is constantly measured directly on the top of the printed circuit board and the infrared emitter is adjusted accordingly. The user can specify a desired pre-heating temperature and the machine heats up the assembly precisely to that. This prevents overheating of the assembly.

Selective soldering itself

All the InterSelect selective soldering machines have a titanium solder pot and can deal with all solder alloys with and without lead. Unlike coated solder pots, titanium ones are

considerably more robust and less susceptible to damage.
In selective soldering, these soldering pots are equipped as standard with InterSelect solutions with a nitrogen coating. The nitrogen atmosphere covers the entire solder bath and prevents the formation of scratches and slag. At the same time, the protective gas flows from the pot via the solder nozzle, thus ensuring an oxidation-free soldering process. Thanks to optimal design, maintenance and cleaning of the solder pot is very easy and with selective soldering it has to be carried out correspondingly less often.

A pump made of titanium ensures that the flow behaviour of the solder in the pump channel is kept even and free from fluctuations. The result is an especially evenly flowing solder wave. The height of the solder wave is set via the pump output. Thanks to wave height monitoring, the actual height of the solder wave is compared with the set value and if necessary automatically corrected. The wave height monitoring ensures constant reproducibility and makes selective soldering particularly attractive.

In particular with the soldering of connector strips in which several pins can be soldered in a line, there is a possibility of building bridges between the last pins. In order to eliminate these bridges, the Interselect units for selective soldering offer a “pull-off” solution. Before the solder nozzle is moved down away from the soldering point, the machine abruptly reduces the pump output. This pulls excess solder from the pin and only the required volume of solder is left, which contributes to the advantages of selective soldering.

Selective soldering manufacturer – InterSelect

InterSelect GmbH – The company for you when you’re looking for a manufacturer and selective soldering

An owner-managed manufacturer of everything to do with selective soldering is at home on every continent

As a manufacturer of units for selective soldering InterSelect can offer products that are very easy, quick and flexible to program. We are outstandingly innovative as a partner and as a selective soldering manufacturer for our customers and we are also a manufacturer of selective soldering solutions that also still develops its own products.
As a manufacturer of units for selective soldering we have over 50 partners worldwide and our company is still managed by our owners. Not only do we give our promise of closeness to the customer but we also keep it. Hundreds of installations on all the world’s continents provide our references which will also convince you. As a renowned manufacturer in the field of selective soldering and everything associated with it, we offer you entry-level solutions and also ergonomic concepts and ideas for island manufacturing. Even fully automatic modular inline soldering units with six assemblies in parallel processing are day-to-day work for us. That is flexibility combined with performance for absolutely every budget!

If you’re looking for an expert and a manufacturer of selective soldering units …
… then at InterSelect you’ve come to the right place! We have over 25 years of relevant experience. If it’s about units that cover all areas of selective soldering, you should contact us!
Current and new technologies such as MicroDrop fluxers with optional flux jet monitoring, a robust solder pot made of titanium, fully automatic wave height monitoring with automatic subsequent adjustment of the wave height, a process camera, pyrometer-controlled top and bottom large area heating, remote control, a Windows PC, operational data recording, automatic sag control with adjustment of the Z axis,

automatic nozzle cleaning and a unique independent programming system are as much a part of our standards as a manufacturer of units for selective soldering as is our reliability in quality and service and they distinguish us as a manufacturer in the area of selective soldering.
Thanks to our selective soldering technology, every individual soldering point may be separately set and adjusted. Would you like an example? With a soldering point with earth connections containing copper, the soldering period can be extended at precisely this soldering point. So you can achieve a perfect soldering result despite difficult conditions. With most applications and with assemblies with SMDs mounted on both sides, there no product-specific solder masks required with selective soldering. Not only does this save cost but it also reduces the throughput time of products.
Only one authorised manufacturer of units for selective soldering achieves this.

Nitrogen and selective soldering – InterSelect

The significance of nitrogen in selective soldering

The perfect soldering point with the aid of nitrogen – and reduced costs at the same time

Nitrogen plays a very important part in the soldering process. For one thing, it reduces scratching and helps to keep down solder costs. But this element has further talents since it reduces surface tension at the soldering nozzle and thereby ensures improved viscosity. This in turn provides the most important precondition for a reproducible soldering process with selective soldering. In InterSelect’s technology, nitrogen is used to protect the soldering nozzle from oxidation. If this important element is missing, the solder coming out of the nozzle is oxidised. Then it is no longer possible to continue the soldering process.

Video with nitrogen


Video without nitrogen


Nitrogen is a chemical element whose German name “Stickstoff” reminds you that you can for instance use it to “suffocate” (ersticken) flames or that every living creature would suffocate in pure nitrogen. At about 78 percent, nitrogen makes up most of our air.
Nitrogen occurs in a large proportion of plant material and is also an important component of all living creatures.

The advantages of using nitrogen with InterSelect soldering units:

• Nitrogen everywhere at all times
• Inexpensive thanks to low operating costs
• Mature and reliable technology
• Precise purity for every application
• No hired packaging as with bottles/packs and tanks
• No CO2 pollution of the environment.

How does nitrogen self—generation work with InterSelect technology?

Pressure Swing Adsorption (PSA) technology is based on the adsorption principle with a carbon molecular sieve (CMS) as the adsorbent.
By adsorption is meant the bonding of particles to the surface of a substance. For the generation of nitrogen, compressed air flows through a container with a carbon molecular sieve. Oxygen molecules react with activated carbon in this process. This adsorption process continues until the activated carbon is saturated with oxygen molecules. Then comes a switch to the second container. The oxygen molecules are again adsorbed. During this process, the other container regenerates.
Pressure Swing Adsorption (PSA) ensures a constant supply of nitrogen of a purity of up to 6.0 / 1.0 ppm (residual oxygen) and delivered volumes of 0.50 – 10,000.00 Nm³/hr.
The technology used by InterSelect is based on the adsorption principle with a carbon molecular sieve. The adsorption process separates the nitrogen molecules from the oxygen molecules. This technology and the special InterSelect process ensures for one thing constant nitrogen production and for another the desired nitrogen purity of up to 99.9999%.

All about selective soldering – InterSelect

InterSelect: All about selective soldering

Over 25 years of experience have gone into our products and services

InterSelect GmbH is your innovative partner where the development and manufacture of soldering machines for selective soldering are concerned. Our entry-level systems achieve high throughput in the smallest space. You will find a compact unit in our individual station systems with a soldering area of 650 x 650 mm. Our inline systems can be expanded on a modular basis and they offer a large number of options. You can process up to six printed circuit boards simultaneously with our modular inline systems. In addition to these, we offer you a nitrogen generator that is the perfect complement to all our products.

More security for your processes: Selective soldering with InterSelect

Thanks to our selective soldering units you can achieve considerable savings compared with wave soldering. Selective soldering also offers very much greater process security compared with manual soldering.

Our company’s worldwide presence ensures that you as our customers always have a contact person close at hand. Over 25 years of experience have gone into our products and services. Get an expert involved if you are considering selective soldering. Trust InterSelect!

Our product range – InterSelect

InterSelect product overview

From entry-level systems to high-end systems we cover your individual requirement

As an innovative partner in all aspects of selective soldering we offer our customers products ranging from entry-level solutions for the price of a manual soldering workstation, individual station systems of small unit size that can nevertheless process large printed circuit boards to inline systems that can be expanded in a modular fashion. But outstanding modular systems consisting of a flux module, a pre-heating module and a soldering module are also to be found in our product range. Nitrogen generators adapted precisely to the consumption levels of our InterSelect soldering units round off our range. We can if desired agree an appointment with you for a soldering trial.

Our salesforce

InterSelect Contacts are available to you all around the world

We at InterSelect value contact with our customers. For this reason we of course would like to be as near to you as possible. So our sales partners are located in many German states from Baden-Württemberg to Mecklenburg-Vorpommern. And we are also present in other European countries from Belgium to Hungary and Russia too. And you will even find InterSelect in North and South America, the Asia-Pacific region, Africa, the Middle East, Israel and South Africa.

Don’t hesitate to contact us! We look forward to providing you with advice completely without obligation. So you will find all our contacts in our list with their direct email addresses.
We can definitely do something for you! We look forward to hearing from you!

AOI for higher quality – InterSelect

AOI – Quality can be created very easily with this

Automatic optical inspection (AOI) is important in particular for checking soldering points

These days, quality assurance is no longer conceivable, in particular with SMD mounting (unlike with the soldering of THT components) without automatic optical inspection (AOI).

Why AOI should be used when soldering THT components:

• If the entire added value lies in the assembly
• If the parts are subsequently enclosed in a housing or covered with a protective coating and can therefore no longer be repaired.
• If you are dealing with a part relevant to safety
• If there is a high cost associated with breakdown in the field or even a danger in the event of a breakdown.

AOI is a system that automatically detects faults in production or in products with the aid of image-processing procedures and then of course reports them. So these systems are of course also to be found in the field of electronics in the automobile industry and in the aerospace industry. It is especially advantageous to ensure fault-free manufacturing with the aid of automatic optical inspection in the manufacture of electronic assemblies after the mounting of components and soldering of printed circuit boards.

The inspection of printed circuit boards can of course be performed not by AOI but by a person. However, it is in the nature of things that this entails a few disadvantages:

• People cannot eliminate their own mistakes and they become tired and need breaks

• Without a microscope it is practically impossible to inspect the fine structures and components of a modern printed circuit board.
• People usually develop their own systems for the classification of faults, which has major consequences, in particular in traceability.

InterSelect offers a standalone solution in the area of AOI

Moreover, the use of AOI technology has now been perfected. In addition to the standalone solution in which the inspection technology is manually loaded, there are also inline systems.
The inline AOI and the inline selective soldering unit communicate via the integrated SMEMA interface, the printed circuit board is transferred entirely automatically from the inline selective soldering unit to the inline AOI and communication between the two devices is conducted via the integrated SMEMA interface. The handling and processing are fully automatic and do not require any operating staff.

For quality control InterSelect offers an AOI standalone device that works in perfect harmony with our selective soldering units.
The combination of multi-coloured LED lighting and a high-resolution colour camera permits an unambiguous 3D assessment for meniscus and short circuit inspection.

The following criteria are checked in the soldering point inspection:

• No solder
• Too little solder
• Solder not flowed around sufficiently
• Solder outside the solder pad (if envisaged in the image detail and possible)
• Short circuits between the solder pads or adjacent conducting paths (if envisaged in the image detail and possible)

AOI – the modern complement to selective soldering!

Alternative to wave soldering – InterSelect

Wave soldering: It’s worthwhile doing a precise calculation at some point

A selective soldering unit may be much less expensive than wave soldering

Wave soldering is still an established technology today where large unit volumes occur with low product variety. However, if a wave soldering unit is getting old or if you are constantly up against the technological limitations of its manufacturing capabilities, you should consider whether or not a selective soldering unit might be the medium of choice.

In particular, anyone who deals with the subject of soldering THT assemblies will quickly discover that a selective soldering unit is not only very much less expensive than a wave soldering unit but also that it offers the opportunity to meet his own customers’ requirements with significantly more flexibility. And what’s the best thing about it? The cycle time remains exactly the same in most cases!

The calculation worth doing regarding wave soldering takes into account the following parameters:

Higher consumption of electricity
Higher consumption of solder
Higher consumption of flux
Additional masking of sensitive points
Increased need for rework
Additional cleaning work on the solder masks
Additional need for cleaning of the soldered assemblies

So overall costs are about five times as high with wave soldering!

Selective soldering is of course a variant of wave soldering used mainly for soldering printed circuit boards that are mounted partly or even entirely with THT components. With InterSelect selective soldering units, nitrogen gassing is standard and the solder pot is designed in such a way that it still resists aggressive lead-free solder after many years thanks to its titanium material.

Wave soldering is normally performed in a protective gas atmosphere because the use of nitrogen offers an opportunity to reduce costs. This process can also be designed to be much more secure. Selective soldering as a form of wave soldering is in any event often the only possible method where wired components on both sides are concerned. However, as specialists in selective soldering we have established that the advantages of selective soldering have not yet been properly recognised everywhere. Wave soldering is also known as flow soldering.

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