20 years

Industry experience

SMT stencil cleaning wipes are specialized consumables used in the surface mount technology (SMT) production line to clean stencil apertures. Their core function is to remove residual solder paste from the apertures, preventing paste blockages that cause printing defects (such as insufficient solder, cold solder joints, and bridging), which directly impact the soldering quality of printed circuit boards (PCBs). The following provides a comprehensive analysis from dimensions including product characteristics, selection criteria, usage specifications, common issues and solutions, as well as storage and maintenance.

Ⅰ. Core Characteristics of SMT Stencil Wiping Paper

1.Material and Structure

The material of SMT stencil cleaning wipes determines cleaning efficiency and compatibility, with mainstream materials divided into two categories:

Wood pulp composite non-woven fabric: Made primarily from natural wood pulp fibers, reinforced with polyester to enhance toughness, it features strong liquid absorption, rapid solder paste adsorption, and extremely low shedding rates. Currently the mainstream choice on the market, it is compatible with the vast majority of solder paste types.

Microfiber non-woven fabric: Woven from polyester and nylon microfibers with diameters of only a few micrometers, it offers higher cleaning precision and can penetrate fine mesh openings to remove residues, making it suitable for cleaning screens used with high-precision fine-pitch components (such as 0201 and 01005 packages).

2. Key Performance Indicators

Chip removal rate: The core requirement is to approach 0, which can prevent PCB short circuits or poor soldering caused by chip residue.

• Absorption rate: Must reach at least 8-10 times its own weight to efficiently adsorb solder paste, reduce wiping frequency, and enhance production efficiency.

Tensile strength: The strength in both transverse and longitudinal directions must be ≥15N/5cm to prevent paper breakage during wiping and debris clogging the screen.

Compatibility: It must ensure no chemical reaction with solder paste to prevent deterioration of the paste and impact on the final soldering effect.

3. Common Specifications

Size: Customized according to the SMT printer model, with common widths of 50mm, 70mm, and 100mm, and typical lengths of 300m/roll or 500m/roll.

Weight: Ranges from 35 to 60g/㎡. Higher weight results in greater paper thickness and better wear resistance, but it must match the wiping mechanism clearance of the printing machine to avoid paper jams.

II. Key Considerations for Selection: Align with Production Requirements

Select according to solder paste type

• Conventional solder paste (leaded / lead-free): Opt for wood pulp composite non-woven wipes, offering high cost-effectiveness and meeting the requirements of most mass production needs.

High-temperature solder paste / Special solder paste: Use ultra-fine fiber non-woven wiping paper for better heat resistance, which is less prone to deformation due to excessively high solder paste temperatures.

2. Select according to stencil precision

Ordinary precision steel stencil (component packaging ≥ 0402): Conventional wood pulp composite material can meet the cleaning requirements.

High-precision stencil (component packaging ≤0201, BGA/QFP packaging): Must use superfine fiber material, with a smooth paper surface free of burrs to prevent scratching the stencil aperture walls.

3. Select the model based on the printing machine type

Different brands of SMT printing machines (such as DEK, MPM, GKG) have specific requirements for the width, thickness, and roll diameter of the paper. It is essential to consult the equipment manual during selection to avoid paper jams or incomplete cleaning due to dimensional mismatches.

4. Select according to environmental protection requirements

For export products or production lines with high environmental requirements: Choose biodegradable wood pulp wiping paper that complies with environmental standards such as RoHS and REACH.

III. Usage Guidelines: Proper Operation Enhances Efficiency and Quality

Preparation Before Using the Machine

• Inspect the appearance: Ensure the wipe is free of damage, impurities, and odors, with the roll being flat and wrinkle-free to prevent cleaning failure due to paper defects.

Dimension Verification: Reconfirm that the paper width and roll diameter match the printing machine's wiping mechanism. Before installation, secure the roll paper firmly to prevent loosening during operation.

Environmental Adaptation: Operate within the cleanroom to prevent external dust from adhering to the wiping paper and contaminating the stencil, causing secondary pollution.

2. Computer Operation Standards

Tension Adjustment During Installation: The paper roll tension must be adjusted during installation. Excessive tightness can lead to paper stretching and tearing, while excessive looseness may cause slippage and insufficient wiping.

Wiping Parameter Settings: Adjust the wiping frequency and pressure based on the steel mesh contamination level. For routine mass production, set wiping every 5-10 printed PCBs; for high-precision products, reduce to every 2-3 printed PCBs. The wiping pressure should be just enough to conform to the steel mesh surface, avoiding excessive force that could damage the mesh.

Cleaning solution pairing: Some production lines may use specialized cleaning solutions to enhance cleaning effectiveness. It is necessary to select a cleaning solution compatible with wiping paper and solder paste, while avoiding excessive usage to prevent residue affecting solder paste activity.

3. Replacement and Recycling

Replacement timing: When the wiping paper surface has excessive solder paste residue, reduced liquid absorption capacity, or paper damage, promptly replace with a new roll to prevent contamination of the stencil.

Waste disposal: Used wiping paper is classified as industrial waste and must be recycled accordingly. Special attention should be given to wiping paper contaminated with special solder paste, which requires disposal in compliance with environmental regulations and must not be discarded carelessly.

IV. Common Issues and Solutions

1. Stencil still has solder paste residue after wiping

The causes are insufficient liquid absorption of the wiping paper, low wiping frequency, and inadequate wiping pressure. The solutions are to replace the wiping paper with one of higher liquid absorption, increase the wiping frequency, and appropriately raise the wiping pressure.

2. Paper tearing during the wiping process

The cause is insufficient tensile strength of the paper, excessive tension adjustment, or burrs on the wiping mechanism. The solution involves replacing the wiping paper with one that meets the tensile strength requirements, readjusting the paper tension, and inspecting the wiping mechanism to remove any burrs.

3. Paper debris residue appears on the PCB surface

The cause is the non-compliance of wiping paper with the required dust-free rate and damaged edges. The solution involves replacing it with high-quality wiping paper with low dust generation and trimming the damaged edges before installation.

4. The wiping paper is incompatible with the printing machine, causing paper jams

The cause is the mismatch between the paper width and thickness and the equipment, as well as the loose installation of the roll paper. The solution involves checking the equipment manual, replacing the wiping paper with matching specifications, and resecuring the roll paper to ensure smooth operation.

V. Storage and Maintenance

Storage Environment: Must be stored in a dry, well-ventilated, and dust-free warehouse to prevent paper mold due to moisture or dust accumulation affecting performance. The recommended storage temperature should be maintained at 15-25°C, with relative humidity between 50%-60%.

Stacking requirements: Wipe paper rolls must be stored upright to prevent deformation from compression, which could affect machine installation. Wipe papers of different specifications and materials should be stored separately with proper labeling to avoid cross-contamination.

Shelf Life: Unopened wipes typically have a shelf life of 1-2 years. Once opened, they should be used promptly to avoid performance degradation from prolonged exposure to air.