11.7 Component Pad Conditioning and Tinning, Leadless Components

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Outline

This procedure covers the robotic tinning of leadless components, including QFN and DFN components.

Caution: Due to the need to completely control the rates of immersion and emersion of the leadless components during tinning, and the dwell times in and between each process step, a robotic hot solder dip is recommended. Semi-automatic or purely manual solder dipping processes may not be capable of completely controlling the rates of immersion and emersion of the component and only provide approximate dwell dipping times in the solder bath. Greater variation in the process may cause a higher chance of damage, including latent reliability problems.

Minimum Skill Level - Expert
Recommended for technicians with advanced soldering and component rework skills and extensive experience in most repair/rework procedures.

Conformance Level - High
This procedure most closely duplicates the physical characteristics of the original, and most probably complies with all the functional, environmental and serviceability factors.


Procedure References
1.0	Foreword
2.1	Handling Electronic Assemblies
2.2	Cleaning
2.5	Baking and Preheating
11.1	Introduction To Component Lead Tinning and Conditioning
IPC J-STD-033	Joint Industry Standard for Handling, Packing, Shipping and Use of Moisture/Reflow Sensitive Surface Mount Device
J-STD-001	Requirements for Soldered Electrical and Electronic Assemblies
J-STD-020	Moisture/Reflow Sensitivity Classification for Nonhermetic Surface Mount Devices
GEIA-STD-0006	Requirements for Using Solder Dip to Replace the Finish on Electronic Piece Parts
Manufacturer's Datasheets	Requirements for case temperature maximum and Moisture Sensitivity Level (MSL)

Tools, Materials and Supplies

Cleaning System
Batch or inline cleaning system for removing fluxes and contamination.

Gloves
Disposable, puncture-resistant gloves designed for handling mild chemicals.

Microscope
Precision microscope with stand and lighting for work and inspection.

Oven
General purpose oven for drying, baking and curing epoxies.

Robotic Deball/Tinning System
Robotic system for component tinning and BGA solder ball removal.

Safety Glasses
Protect your eyes and your vision with proper safety glasses.

Solder Flux
Used to prepare solder surfaces and to prevent formation of oxides during soldering.

Tweezers
Multiple sizes and tip configurations of tweezers for various small parts handling needs.

Vacuum Pickup Tool
Manual or powered vacuum pickup tool for handling small parts and electrinic components.

Wipes
Nonabrasive, low-linting wipes for cleanup.

Procedure

Ensure the components meet the acceptable Moisture Sensitivity Level (MSL) for processing.
Note: For details on baking and moisture control, refer to Procedure 2.5 Baking and Preheating.
Use a matrix tray or fixture tray to position the components for pickup by the robotic tinning system. (See Figure 1)
Set up the robotic tinning system with the proper process parameters, including solder immersion depth, dwell times, insertion and extraction speeds, solder temperature, and other settings. (See Figure 2)
Note: Consult the component datasheet for peak temperature limits and other specific guidelines.
Place the components into the tray and position the tray in the system's staging area. (See Figure 3)
Initiate the robotic tinning system's process cycle.
The system will use a vacuum-pickup (single or multi-head) or mechanical grippers to retrieve one or more components from the tray. (See Figure 4)
The system will apply flux to the terminations, then pass the components through a preheat stage to activate the flux and to prevent thermal shock to the components.
The robotic arm will dip the terminations into the solder pot or solder wave and manipulate the components to ensure complete solder coverage.
A filtered hot water rinse or other flux remover required by the flux type selected may be used to remove flux residues, followed by a drying cycle.
After tinning, the system will return the tinned components to their original position in the matrix or precision-machined tray.
As required, complete the cleaning by washing the components in a cleaning system.
As required, dry the components in a general-purpose convection oven. Temperatures not to exceed 100°C. Note: this is not to be used as an MSL bake schedule.
Visually inspect the components for appearance, cleanliness, and general condition. Confirm proper solder coverage on the terminations.
As required before packaging and shipping, MSL dry-bake the components in a general-purpose convection oven according to the temperature and time requirements to meet the Mixture Sensitivity Level J-STD-003.

Evaluation

Visual examination
Tests or other inspection criteria as specified.

Images and Figures

Tinning, QFN/DFN Components, Robotic Method

Figure 1. Use a matrix tray or fixture tray to position the components for pickup.

Figure 2. Set up the robotic tinning system with the proper process parameters.

Figure 3. Place the components into the tray and position the tray in the system's staging area.

Figure 4. The system will use a vacuum-pickup or mechanical grippers to retrieve one or more components from the tray.

11.7 Component Pad Conditioning and Tinning, Leadless Components

Condition and tin leadless component pads using controlled solder techniques. Covers surface preparation and inspection to verify uniform solderability for reliable attachment. Minimum Skill Level: Expert Conformance Level: High

Condition and tin leadless component pads using controlled solder techniques. Covers surface preparation and inspection to verify uniform solderability for reliable attachment.

Minimum Skill Level: Expert
Conformance Level: High