Chemical tin solution for flexible printed circuit board

Abstract

The invention provides a tin solution for soft printed circuit board; it includes tin salt compound, complexant, inorganic acid or organic acid with the functional group to tin salt compound, corrosion inhibitor, surface activator, conformity agent, and antioxidant. The corrosion inhibitor can prevent the corrosion phenomenon on the copper surface under the covering material bond, avoids from tin pit, the fluorine surface activator is used as wetter, it can upgrade the outlook of the plating layer.

Description

technical field [0001] The invention relates to materials for surface treatment of flexible printed circuit boards, in particular to a chemical tin solution for flexible printed circuit boards. Background technique [0002] Flexible circuit is a kind of internal connection form of printed circuit designed and formed on a thin and arbitrarily bendable substrate. It can be folded or bent in a very small three-dimensional space, which is impossible for rigid circuit boards. Therefore, flexible circuit boards are widely used in products with extremely small three-dimensional space, and require long-term and multiple bending and folding to ensure reliable service life, such as mobile phones, digital cameras, digital cameras, fax machines, notebooks Computers, printers, hard drives, optical drives, dashboards, etc. [0003] The materials used in the existing flexible circuit board mainly include: base material, which is generally made of polyimide film, polyester film, glass fibe...

AI Technical Summary

Problems solved by technology

[0005] However, the above-mentioned existing chemical tin solution can only be applied to rigid circuit boards, and is not suitable for use on flexible circuit boards, especially when using acrylic or epoxy resin adhesive film materials as covering layers For flexible circuit boards, because this chemical tin solution, after use, will form a tin pit on the copper surface under the adhesive at the interface point between the cover material and the copper substrate. The appearance of the tin pit will make the The firmness of the interface is reduced, and the thickness of the copper base material under the tin pit is reduced. In this way, after the circuit board is bent and folded many times, the circuit may be broken and cannot work normally, which greatly damages the use of soft parts. Reliability of performance of electronic devices with flexible circuit boards as internal connectors

In addition, the surface color of the flexible printed circuit board treated with this chemical tin solution is uneven, especially the surface near the joint of the covering layer and the exposed copper, which is not bright and white, and appears gray or dark gray to some extent. Areas with poor surface color will affect the subsequent assembly process due to low solderability