Dr. Reinhardt Seidel DEEPTRONICS GmbH, Johannes Ollech and Manuel Hart Sentinum GmbH
A case study on steamlining selective wave soldering process setup
Take aways
- Cut trial and error in preheating and soldering by 50% through precise calculations.
- Achieve preheat temperature calculations with an error margin of just ±8°C.
- Determine optimal solder contact times on the first attempt.
- Boost production cycle time efficiency by 25%.
The Problem:
Inefficiencies in THT Process Setup Are Costing You
Your customers are unwilling to foot the bill for inefficiencies in your process setup. Setting up a new soldering process often requires multiple trial-and-error cycles to identify the optimal parameters for preheating and wave soldering. These iterations are time-consuming, waste resources, tie up machine capacity, and ultimately lead to financial losses.
Setting up a new soldering process usually requires multiple trial and error cycles to identify the product specific set of parameters for preheating and soldering. These multiple iterations are time consuming, resource wasting and machine capacity consuming and ultimately end up in loss of money.
The figure shows the iterative activities that have to be done to setup the preheating and soldering parameters of a selective wave soldering process for through hole technology (THT).
The Challenge that causes iterations
There are no standardized rules or labels on components or PCBs indicating the required soldering energy. This forces you to rely on trial and error to determine optimal settings. Your task is to find parameters that meet the thermal demands of electronic component pins placed in plated through holes (PTH) of a printed circuit board (PCB), often multilayered.
Wave soldering involves complex physical phenomena, making it difficult to establish a working process setup without experimentation. Hitting the absolute optimum without trials is nearly impossible. Default parameters may sometimes work but can lead to overshooting thermal requirements for easy solder joints or underestimating those for more challenging ones. This results in multiple trial-and-error cycles during THT process setup.
The Solution: First-Time-Right THT wave soldering Process with Digital Twin Simulation
Making informed decisions on process parameters can reduce both the cost and time for setup while enhancing cycle time efficiency. Here’s how:
1. Preheat calculation
with the Digital twin of the machine
By utilizing a digital twin of the soldering machine, you can calculate the preheat profile and simulate preheat parameters specific to your product. This allows you to select process temperatures and flux materials without iterative measurements.
The validation of the preheat temperature calculation on the PCB top side in the figure proves good fit between calculation and measurement. Based on this calculation the preheat parameters can be chosen to suit the flux (REGI 007) process window.
In our case study using a 4-layer PCB layout of a sensor application (1.0 mm thick), the error between calculated and measured temperature development is only between 5°C and 10°C. This is an excellent first attempt, considering variable conditions inside the preheating stage and minimal product data used. After leaving the preheating module, the global PCB temperature gradually cools down, even during soldering.
2. Digital solderability analysis of the PCB layout
Conducting a PCB analysis for THT solderability provides a relative measure to evaluate each solder joint. Solder joints are color-coded—green indicates easier-to-solder joints, while red signifies more challenging ones.
This analysis helps soldering experts identify the most difficult solder joints immediately. Starting the soldering sequence with the most challenging joints ensures that the PCB has not cooled down significantly after preheating, allowing for shorter solder contact times. By sequencing from red to green, you optimize process efficiency.
3. Calculating Optimal Solder Contact Times in Selective Wave Soldering
Finding the right solder contact times for each solder joint balances achieving acceptable hole fill per IPC-A610 standards and avoiding thermal damage to the PCB and components.
The required solder contact time for each joint can be calculated based on:
· Solder temperature
· Preheat temperature
· Nozzle size
· Solder alloy
As shown in the table, individual solder contact time recommendations can significantly improve efficiency. Compared to a default setting of 2 seconds per joint, these calculations can lead to a 25% faster cycle time.
The recommended solder contact time is 3 seconds for the most challenging solder joint (No. 15). Using machine learning-based estimation of hole fill over time, this can be validated through time-hole fill scenario calculations at different soldering temperatures.
Optimizing solder contact time without knowing the inner layer connections is like playing darts blindfolded—you’re unlikely to hit the target.
Conclusion: Achieve Efficiency and Precision with Digital Twin Technology
Ultimately, leveraging digital twin-based process simulation allows you to dramatically reduce trial-and-error cycles traditionally associated with THT process setup. This not only cuts down on setup time and costs but also optimizes production efficiency and product quality.
Benefits at a Glance:
- 50% Reduction in Trial and Error: Save time and resources by accurately calculating preheat and soldering parameters from the start.
- Precision Within ±5°C: Achieve highly accurate preheat temperature calculations, minimizing the risk of thermal damage.
- Optimal Solder Contact Times: Determine the best solder contact times on the first try, enhancing product consistency.
- 25% Faster Cycle Times: Increase production efficiency by optimizing soldering sequences and parameters.
Take the Next Step Towards Optimized THT Processes
Don’t let inefficient setups drain your resources. Embrace digital twin technology to achieve right-first-time setups and stay ahead in the competitive electronics manufacturing industry.
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