6 Selective Soldering Profiling. IPC IPC-7530A

IPC-7530A provides guidelines for developing thermal profiles to produce acceptable tin-lead and lead-free electronics assemblies. It is a comprehensive document which covers various aspects of temperature profiling for mass soldering processes, including reflow and wave soldering. This document is intended for managers, design and process engineers and technicians who deal with mass soldering processes.

PDF

Document

IPC-7530A Draft Document for Industry Consensus Only August 2016 components. This space allows the wave fixture to hide surface mount components from the wave while selectively soldering through-hole components.

6 SELECTIVE SOLDERING PROFILING

6.1 Solder Pot

By definition, selective soldering implies creating multiple solder connections sequentially or in mass in a semiautomated or automated process.

Equipment designed for this task generally has four basic characteristics:

• PWB conveyance (if PWB moves)

• Pot and fluxer conveyance (if PWB is stationary)

• Fluxing capability

• Preheating capability

• Molten pot of solder with a single nozzle (sequential soldering)

• Molten pot of solder with a nozzle fixture (mass soldering)

The differences between manufacturers are in the application of these basic concepts and the equipment controls.

Each machine has unique characteristics that need to be taken into account when developing a thermal profile.

Sequential selective soldering machines solder through-hole components in a sequence. The advantage of sequential selective soldering is that PWBs with bottom-side surface mount components can have through-hole components soldered without PWB fixturing and masking. The disadvantage is speed because the process uses sequential soldering instead of mass soldering (i.e. wave soldering).

Mass selective soldering machines solder through-hole components simultaneously using a custom nozzle fixture.

The advantage of mass selective soldering is that PWBs with bottom-side surface mount components can have through-hole components soldered without PWB fixturing and masking. The disadvantage is the need for a custom nozzle fixture for each PWB. The selective soldering system automatically performs the soldering process, which is flux application, preheating of the area to be soldered, application of molten solder and solidification. All of these characteristics act together to ensure proper soldering. A solder recipe is developed by recording the optimum process parameters selected for conveyance speed, flux application, preheaters and solder temperature.

6.1.2 Machine Considerations

Each part of a selective soldering machine has a unique function to perform but they must be considered as a whole system because of the interrelationships and dependencies of the fluxer, preheaters, nozzles and solder pot.

Of particular concern is the correlation of the time/temperature/volume relationships. The molten solder temperature is usually a constant; the variables are preheater temperatures, preheat/solder pot dwell times and volume of solder over the nozzle. Dwell time in preheat and over the solder pot are the prime thermal profile variables.

6.1.3 Preheat Considerations

PWBAs are preheated during selective soldering for various reasons. These include:

Key features

Thermal Profile Development for Mass Soldering
Reflow and Wave Soldering Processes
Temperature Profiling Requirements
Guidelines for Solder Alloy Selection
Optimizing Profiles for Different Applications
Solder Joint Quality and Reliability
Troubleshooting Common Soldering Defects

Frequently asked questions

The primary purpose of this document is to provide practical information to those responsible for developing thermal profiles for mass soldering processes, including reflow and wave soldering. It aims to ensure the production of high-quality solder joints by optimizing the temperature profile during the soldering process.

Temperature profiling is crucial for ensuring consistent and reliable solder joints. It helps to control the heating and cooling rates during the soldering process, preventing damage to components and the printed wiring board (PWB). A well-defined thermal profile ensures that all solder joints reach the required temperature for proper metallurgical bonding.

This document primarily focuses on two common mass soldering processes: reflow soldering and wave soldering. It provides specific guidelines for developing thermal profiles for both processes, considering the unique characteristics and challenges of each.

IPC-7530A provides guidelines for developing profiles that accommodate both tin/lead and lead-free components. It highlights the importance of considering the different melting points and temperature requirements of each type of component during profile development.

User questions

Patricia K.

What factors are important when creating a wave soldering thermal profile?

The solder alloy and flux limitations, component and substrate specifications including their limitations, web width for conveyor speed calculation, preheat zone temperature settings, solder pot temperature setting, and cooldown settings are crucial factors for developing a wave soldering thermal profile with preheat, soldering, and cool down phases.

Linda L.

How can heat sink effects be minimized during mass wave soldering?

Use thermal relief for large metallic planes like ground planes to minimize thermal sinking and ensure even heat distribution.

Linda L.

How can good soldering quality be ensured with surface mount components in mass wave soldering?

Align surface mount components parallel to the wave to ensure smooth solder flow and consistent contact with component leads.

Linda L.

What are considerations for using selective wave soldering pallets?

Ensure adequate clearance for components and proper alignment to prevent soldering failures. Proper clearance for older components and proper alignment for surface mount components are crucial.

Linda L.

How can component movement be prevented during mass wave soldering?

Secure large components like connectors and sockets to prevent movement and avoid misalignment or damage during soldering.

Mary J.

What is the lifespan of a type K thermocouple?

The viewed document does not specify the lifespan of a type K thermocouple. However, the lifespan of a standard thermocouple and sample board is estimated at 15-30 profiles, depending on factors such as PWB thickness and laminate type. Reattaching the thermocouple to multiple assemblies reduces lifespan to 3-5 profiles.

Linda L.

How does the distance of soldering connections to the PWB edge affect mass wave soldering?

The distance from soldering connections to the PWB edge affects heat conduction and the thermal profile. Connections should be sufficiently far from the edge to prevent soldering problems.

Linda L.

How does PWB rigidity at maximum soldering temperature impact mass wave soldering?

PWB rigidity affects its ability to withstand heat and deformation during soldering. A rigid PWB helps maintain a consistent thermal profile, ensuring good soldering quality.

Michael I.

What are the guidelines and requirements in IPC-7530A for creating thermal profiles in mass soldering processes?

IPC-7530A provides guidelines and requirements for developing thermal profiles to ensure high-quality solder joints in reflow and wave soldering. It covers key terms, profiling methods for various soldering types, temperature profiling tools, and troubleshooting soldering defects.