VisionXS

The flexible Reflow Soldering System with futures 

As a co-founder of modern ReflowConvection-Soldering Systems the company Rehm has been established successfully since 1990 in the national market as well as worldwide. The know-how and experience in reflow technology of many years is now integrated in the VisionXS-series. Optimized for customer requirements the VisionXS stands for productivity and flexibility.

The Transport System

Maintenance and downtime are reduced by means of a continuous process based on an absolutely reliable conveyor, as well as an ingenious mechanical system.  The conveyor system has been laid out in accordance with requirements specified for future placement machines, and optional for a maximum width of 508 mm. The optionally available center support makes it possible to process large panel formats – an additional advantage for flexible manufacturing!

Ideal Heat Transfer

Heat transfer has been significantly optimized for the VisionXS through the use of two, three or four peak zones. Minimal distance between the nozzle sheets and the conveyor, as well as separately adjustable flow rates for the upper and lower heat zones, assure that the PCBs are heated up in an extremely uniform fashion. Stressing within the PCBs is thus minimized, and related soldering defects are reduced.

Stress-free below 50°

Depending upon the length of the system, the cooling tract in the VisionXS nitro is laid out in 2-, 3 or 4 stages. The fans in the individual zones, which can be controlled separately as an option, allow for accurate control, and cooling gradients can be correspondingly influenced. This assures stress-free cooling for your PCBs to below 50° C, for lead-free soldering as well.

The Residue Management System

Residues which accumulate during soldering are separated by a new residue management system included in VisionXS systems. The 3-stage Residue-Management System is integrated in the oven. Each stage consists of a cooling and a filter unit. For processes with an extremely high amount of residues the extended Modular Residue-ManagementSystem (MRS) can be attached. This guarantees an absolute stable process and reduces down-time. Both systems are exchangable for the existing machine.

Benefits:

  • optimal cleaning
  • easy to maintain
  • easy accessibility
  • MRS can be attached
  • additional process gas cleaning
  • stable process
  • exchangeable

Nitrogen Control

With the nitrogen control the desired ppm level is held constant by continuously measuring the residual oxygen value. This is accomplished by injecting nitrogen into the process chamber in a variable fashion depending upon the measured residual oxygen value. This results in varying nitrogen consumption levels depending upon the extent to which the reflow system is loaded with PCBs and the selected conveyor width, allowing for reduced nitrogen consumption. Nitrogen control is advisable for flexible SMD production lines with variable loading circumstances and conveyor widths.

Airdoping

In the case of air doping, the process chamber is contaminated with atmospheric oxygen. A defined leak is created in the process chamber by means of a servo-valve to this end, which is opened just far enough to generate the desired residual oxygen value. The reflow system’s nitrogen consumption is not influenced by this procedure, and always remains constant. Air doping is advisable for SMD production lines for which loading circumstances and conveyor widths vary only minimally in the reflow oven.

OPTION

 

  • SOFTWARE
    • Product management
    • Traceability packages
    • Process interlock
    • ProCap
    • Profile Creator
    • KIC implementation
    • RPI
    • MES-Option ROI
    • ProMetrics

 

  • ENERGY EFFICIENCY
    • without heat emission
    • Measurement power cons.
    • Measurement nitrogen consumption
    • Supervision of volume flow with active readjustment

 

  • OTHERS
    • Stand-By-Mode
    • SSP
    • SSP+
    • Quick Exhaust
    • Transmission zone
    • Fan speed regulation
    • Pin in Paste

with flexible transport systems

Your component will run through various sections of the system during the soldering process: from the preheating zone, through the peak zone to the cooling zone. Secure transportation is a key entity when it comes to continuous processes. Rehm offers flexible systems for this.

Our transport systems provide the perfect fit for your components regardless of the circuit board geometry. Transport lanes and speeds are variably adjustable and enable parallel soldering processes with lead-free or leaded soldering in one reflow system. Depending on the product requirements, you can choose from
various transport models such as individual and double track transport, quadruple or multi-track transport.
The optional centre support enables even the processing of large circuit boards or boards with a flexible base material with ease and prevents any sagging during the reflow soldering, thus guaranteeing a maximum degree of process stability.

Integrated Filter Monitoring

Predictive Maintenance – Effective Residue Management through Integrated Filter Monitoring

Convection soldering system VisionXP+ from Rehm Thermal System enables predictive maintenance and safe, stable processes

Optimum soldering results depend not only on the actual melting process of the solder paste. Cooling the assembly to be soldered plays an important role in soldering highly complex electronic components. The filter monitoring – including volume flow control integrated in the convection soldering systems of the Vision series from Rehm Thermal Systems – ensures effective residue management and constant cooling capacity, thereby supporting stable and safe performance of the soldering process.

When the solder paste melts inside the process chamber, process gases are produced which cause contamination of the cooling modules and the fine filter. The volume flow of the cooling process, which should be as constant as possible, is reduced by these contaminants. Less volume flow means less cooling capacity at the same time, which can lead to an increase in the outlet temperature or to a changed cooling gradient at the assemblies. However, for a safe and stable process, the correct run-out temperature and a constant cooling gradient of the soldered assembly are of great importance.

The filter monitoring with active readjustment automatically detects via the integrated control system when the volume flow falls below the level individually set by the customer to meet his production requirements. This is an indication that the filter is about to be changed. Until this change is made, the system automatically readjusts the volume flow by means of active readjustment in order to continue cooling the assemblies within the specified process window by increasing the cooling capacity. For this purpose, the set gas flow rate in the cooling zones is continuously compared with the value actually determined.

The filter monitoring with active readjustment thus guarantees a high level of process reliability and ensures an optimum reflow soldering process with constant flow conditions. In addition, the data from the filter monitoring with active readjustment can be collected and used to predict the next filter replacement with external data analysis programmes.

Attached is a graphic of the volume flow control of the cooling section (graphic: Rehm Thermal Systems).

Cooling process and individual adjustment of the cooling gradient

Rehm Thermal Systems offers various types of cooling for the VisionXP+ convection soldering system

The standard cooling system installed in all Vision convection soldering systems consists of up to four individual cooling modules. These allow a precisely controlled cooling process as well as individual adjustment of the cooling gradient. For the cooling process, a small part of the warm and charged air volume present due to the soldering process is first extracted into the lower part of the system. It is then cleaned over several cooling modules and cooled to the desired temperature (usually below 20 °C). The air is then blown back from above onto the assembly, which results in the cooling. The “closed loop principle” guarantees a closed atmosphere cycle. The standard cooling section consists of active and passive cooling modules. The active cooling modules are supplied with water via a heat exchanger. The cooling filters can be easily cleaned and serviced at the rear of the system: the process chamber does not need to be opened to do this.

Gentle cooling with Power Cooling Unit

For gentle cooling, especially for complex assemblies, an extended cooling section can be connected to the VisionXP+. This can be implemented as an extension to standard cooling zones under a nitrogen atmosphere or as a separate, downstream module (“Power Cooling Unit”) in an air atmosphere for higher cooling performance for insensitive materials. Advantage of the air-cooled variant: while nitrogen is needed in the process section of the convection unit to prevent oxidation, the extended cooling section no longer needs to be flooded with nitrogen, resulting in nitrogen savings.

Underside cooling for uniform cooling from above and below

For particularly massive or large assemblies or boards with product carriers, the VisionXP + can also be equipped with underside cooling. The actual cooling process is identical to that of the standard cooling section, but the extracted, cleaned and cooled air flows not only from above onto the module, but also from below.

.

Gradual cooling for energy saving

Rehm also offers an energy-saving cooling variant for the VisionXP+ convection soldering system: the air is extracted at several points rather than just one. This results in gradual cooling and offers significant energy saving potential.

Rehm CoolFlow: reduced energy usage with liquid nitrogen

Along with their partner Air Liquide, Rehm has developed a cooling system (“Rehm CoolFlow”), which uses the nitrogen used for inertia even more efficiently. The -196°C liquid nitrogen releases its energy in the cooling section, then evaporates and can then be used in its gaseous state for inerting the process atmosphere. The cooling water, which previously required high energy use for cooling, including cooling unit and refrigerant, is completely eliminated.

Cooling process and individual adjustment of the cooling gradient

Rehm Thermal Systems offers various types of cooling for the VisionXP+ convection soldering system

The standard cooling system installed in all Vision convection soldering systems consists of up to four individual cooling modules. These allow a precisely controlled cooling process as well as individual adjustment of the cooling gradient. For the cooling process, a small part of the warm and charged air volume present due to the soldering process is first extracted into the lower part of the system. It is then cleaned over several cooling modules and cooled to the desired temperature (usually below 20 °C). The air is then blown back from above onto the assembly, which results in the cooling. The “closed loop principle” guarantees a closed atmosphere cycle. The standard cooling section consists of active and passive cooling modules. The active cooling modules are supplied with water via a heat exchanger. The cooling filters can be easily cleaned and serviced at the rear of the system: the process chamber does not need to be opened to do this.

Gentle cooling with Power Cooling Unit

For gentle cooling, especially for complex assemblies, an extended cooling section can be connected to the VisionXP+. This can be implemented as an extension to standard cooling zones under a nitrogen atmosphere or as a separate, downstream module (“Power Cooling Unit”) in an air atmosphere for higher cooling performance for insensitive materials. Advantage of the air-cooled variant: while nitrogen is needed in the process section of the convection unit to prevent oxidation, the extended cooling section no longer needs to be flooded with nitrogen, resulting in nitrogen savings.

Underside cooling for uniform cooling from above and below

For particularly massive or large assemblies or boards with product carriers, the VisionXP + can also be equipped with underside cooling. The actual cooling process is identical to that of the standard cooling section, but the extracted, cleaned and cooled air flows not only from above onto the module, but also from below.

.

Gradual cooling for energy saving

Rehm also offers an energy-saving cooling variant for the VisionXP+ convection soldering system: the air is extracted at several points rather than just one. This results in gradual cooling and offers significant energy saving potential.

Rehm CoolFlow: reduced energy usage with liquid nitrogen

Along with their partner Air Liquide, Rehm has developed a cooling system (“Rehm CoolFlow”), which uses the nitrogen used for inertia even more efficiently. The -196°C liquid nitrogen releases its energy in the cooling section, then evaporates and can then be used in its gaseous state for inerting the process atmosphere. The cooling water, which previously required high energy use for cooling, including cooling unit and refrigerant, is completely eliminated.

PWI monitoring tool

The new ProMetrics monitoring tool from Rehm Thermal Systems offers optimal control and top quality when soldering electronic assemblies

With ProMetrics, Rehm Thermal Systems has developed an instrument for monitoring thermal profiles during soldering. It checks how well the previously created profile corresponds to the required, predefined specifications. The process window index (PWI) ascertained in this way is a statistical measure that quantifies the quality of a thermal process. This is mostly determined by the specification of the solder paste and the most heat-sensitive component. The following applies as a general rule: The lower the PWI, the better the profile and thus the more efficient and stable the process.

 

The generation of real-time data for each component allows the exact determination of the assembly position and reliably detects any deviations or delays in the soldering system. Process changes can thus be detected immediately. This leads to the greatest possible reliability in the calculation of the temperature profile of an assembly.

By integrating ProMetrics into the ViCON software, errors in data transmission to a higher-level system, such as MES, can be excluded and are available centrally in the MES for each assembly. Uniform logging in ViCON ensures the necessary transparency and traceability. Repeated maintenance of data is not necessary and the susceptibility to errors is significantly reduced.

A representation of the envelope curve visualises any deviations of the soldering profile from the specified parameters. Alarm messages in the ViCON show these deviations from the temperature profile outside the

envelope curve.

In order to be able to use ProMetrics from Rehm Thermal Systems effectively, both software and hardware components are required for optimal quality control of the soldering profile. The Solderstar software with the associated licence dongle is used to record the data. The Solderstar software is integrated into the ViCON and helps with thermal profiling. Using a measurement data logger from Solderstar, temperatures of a reference board are recorded in order to be able to check the process stability of the system. The system is equipped with monitors to record the temperatures; in addition, the temperatures in the heating zones are recorded by sensors.

Temperature profiling with Solderstar equipment

With Solderstar, Rehm Thermal Systems gains from a competent partner boasting many years of expertise in this area for the creation and optimisation of temperature profiles during reflow soldering. The Solderstar PRO thermal profiling systems contain a compact data logger with Solderstar Smartlink connectors. The system transmits live profile data directly to Solderstar’s AutoSeeker software.

ProMetrics can be used for single and dual lane systems and is the first system in the world that is also suitable for vacuums.

ProCap – Soldering Process Capabilities

It is the objective of every soldering process to produce only high quality solder joints during PCB production without performing any rework.
The quality of a solder joint is characterized by:
› Electrical conductivity
› Adequate mechanical strength
› Good reliability under conditions of use
› Good visual appearance
In routine soldering practice, the quality of a solder joint is evaluated on the basis of optical criteria (e.g. IPC 610 C). The results of this evaluation are generally expressed in terms of
a good, or a bad solder joint. It is extremely difficult to obtain objective, comparable process capabilities for attributive quality characteristics of this sort. ProCap ensures process stability of the reflow soldering system for each individual product.
The process parameters are automatically stored for the
product at the first attempt. Each additional job is compared
with the parameters stored for this product. Each board is saved to the current product and order and, if available job numbers and serial numbers are also stored. Process deviations and operator errors are logged continuously. Stealthy changes such as a contaminated filter are reliably detected.

VisionXP+ Vac convection soldering system

The cycle time of the VisionXP+ Vac convection soldering system by Rehm Thermal Systems is defined by the time which is required to complete the vacuum step. This includes the transportation of the product into the vacuum chamber, the closing of the vacuum chamber, the time until the target pressure has been achieved, the dwell time at the target pressure, the ventilation of the chamber and the opening of the chamber. However, productivity can be further increased using a two-track system with central support, scalable vacuum chamber sizes for optimum adaptation to the respective product and an optimised temperature/pressure/time profile. This is possible with the VisionXP+ Vac. With regard to profiling, the ViCON software by Rehm Thermal Systems enables the combined temperature/pressure/time profile to be created in a convenient manner. In this regard, we should not lose sight of the fact that pressure gradients which are too high during the creation of the vacuum may increase productivity but may also lead to process errors such as solder beads or components which slip out of place. Therefore, profiling enables the combination of maximum productivity and maximum process reliability to be found. In summary, the VisionXP+ Vac enables large-scale production on an inline reflow soldering system and features an optional vacuum for void-free processes.

 

Resource efficiency and CO2 footprint

In addition to the total cost of ownership, CO2 footprints are becoming increasingly important. Consumption of electricity, nitrogen and coolant, as well as heat loss, should therefore not just be reduced for economic reasons but also to promote environmentally-friendly and climate-friendly production. With respect to the local energy mix in Germany, 1 kWh corresponds to an equivalent of 0.49 kg CO2 emissions and 1 m3 nitrogen corresponds to approx. 0.5 kg CO2 emissions. An energy saving of 30% by replacing AC motors with EC motors therefore corresponds to a reduction of the CO2 footprint by approx. 5%. Precise regulation is required to reduce nitrogen consumption. On top of this, the innovative option of Rehm CoolFlow facilitates the optimisation of cooling and nitrogen consumption. Liquid nitrogen is used in the cooling zone for more efficient cooling and the gaseous nitrogen that is created is used for inerting the process chamber. This means that less energy is required to provide the coolant, while the nitrogen is used twice, leading to a reduction of CO2 emissions by 15% in total.

 

Another aspect of resource efficiency is the maintenance intervals and service times. In order to keep the maintenance intervals as long as possible, functions such as vibration measurement on the transport system are used to identify contamination and wear on the chain. The pyrolysis unit typically reduces the contamination in the machine, while the heat loss from pyrolysis is returned to the heating zones. For the VisionXP+ Vac by Rehm Thermal Systems, the current energy and nitrogen consumption is very easy to monitor with the ViCON software. Furthermore, all data on resource efficiency can be recorded and logged, as well as transmitted directly to the management execution system (MES).

 

In conclusion, the resource-friendly consumption of energy is a primary goal of the most recent developments in order to reduce running costs and CO2 footprints. Innovative features combine the reduction of energy and nitrogen consumption to achieve the best process results with as low a CO2 footprint as possible for inline reflow soldering systems both with and without a vacuum.