How to avoid short circuits in close-pin ics during the use of SMT solder paste?

inSMTSolder pasteDuring use, most of the adverse phenomena occur in the tight feetICIn. "密脚" 可 以 翻 译 为 "tight feet"ICUsually, the pointer pins are relatively denseICComponents, and the spacing between the pins is small, with dense pinsICThere are certain conditions required for a good weld. If one is not careful, it is easy to have a short circuit, a poor processing phenomenon, which will also affect the performance and quality of the product. Now, let's have Shenzhen JJY Solder Paste Manufacturer introduce some common ways to avoid tight solesICSome methods of short circuit:

1. Steel mesh

Steel mesh is used to prevent solder paste or surface mount adhesive from being missedPCBOn the solder pads, preparations are made for the soldering of components. For0.5Millimeters and belowICThe opening method of the steel mesh remains unchanged in the length direction, but the width is usually0.5to0.75The width of the pad and the thickness are generally0.12to0.15millimeter. Steel mesh must be fabricated by laser cutting technology and polished to achieve good tinning and forming printing effects.

Ii. Solder paste

Solder paste is a semi-solid substance composed of metal powder and flux paste, which is used to provide the metal materials and chemical reactions required for soldering. inSMTSelect the dense pin in the patchICThe particle size of the solder paste needs to be selected20~38um(PITCH≤0.4mm)Viscosity160~220pa.sThe solder paste, the activity of the solder paste is generally adoptedRMAGrade.

Iii. Printing

Printing usually refers to scraping solder paste from a steel meshPCBThe process on the board, forSMTThe welding effect of surface mount technology (SMT) processing also has a direct impact. Printing usually requires attention to the following aspects:

1.The types of scrapers: Scrapers are mainly made of plastic and steel. For fine-pin chips, steel scrapers should be chosen to facilitate the formation of solder paste.

2.The Angle of the scraper: The scraper is at45°The operation Angle of solder paste printing can improve the imbalance phenomenon of different steel mesh openings facing upwards.

3.Printing speed: AtSMTThe speed of the squeegee is also a key parameter in the solder paste printing of surface mount technology. If the speed is too fast, it may cause the solder paste to be missed. If the speed is too slow, the solder paste may stop rolling, resulting in poor resolution of the solder paste on the pad, usually for those with dense pinsIC PCBPrinting speed10mm/s~20mm/s.

4.Printing methods: In actual production and processing, the common printing methods mainly include contact printing and non-contact printing. Contact printing has higher precision and is more suitable for fine-pitch solder paste printing.

Iv. Mounting Height

SMTFor processing plantsPITCH≤0.5mmtheICIt should be adopted during mounting0Distance or0~-0.1mmThe mounting height should be adjusted to prevent the solder paste from forming and collapsing due to an excessively low mounting height, which could cause a short circuit during backflow.

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