Release time：2024年4月1日
Author：Kama
Solder, an alloy of metals, is utilized to form a durable and conductive connection between electronic components and the circuit board. In the realm of printed circuit boards (PCBs), soldering entails melting the solder alloy and applying it to create a linkage between the leads or pins of components and the copper traces or pads on the board. As the solder cools and solidifies, it establishes both an electrical pathway and provides mechanical stability, securing the components firmly in place.
When soldering an electronic connector to a contact point, often termed a "pad," the essential items usually include:
1.A soldering iron capable of reaching the solder's melting point.
2.Wire solder, available with or without a flux core.
3.Flux, required if the wire solder doesn't have a flux core or if additional flux is necessary.
Determining the optimal solder type for circuitry often hinges on the specific application and demands. Nonetheless, here are some frequently utilized high-quality solder varieties for electronic circuitry:
Tin/Lead Solder Wire, with a composition of 63% tin and 37% lead, is widely used in electronic soldering. It boasts a low melting point of approximately 183 degrees Celsius, making it easy to work with and ensuring reliable connections. However, due to growing environmental and health concerns associated with lead, there is a rising availability of eco-friendly alternatives.
Solder Wire Blend of 60% Tin and 40% Lead: This solder wire composition, akin to the 63/37 ratio, finds extensive application in electronic soldering. It boasts a marginally elevated melting point while remaining convenient for manipulation.
Tin Alloys Without Lead: Given the environmental and health concerns associated with lead, contemporary soldering practices favor lead-free tin alloys. These solders commonly incorporate blends of bismuth, silver, copper, among others, offering elevated melting points and favorable mechanical characteristics.
SAC Alloy Lineup: A favored lead-free solder choice, the SAC series features SAC305 (96.5% tin, 3% silver, 0.5% copper), and similar compositions. Widely adopted in the electronics manufacturing realm, these alloys are pivotal for meeting environmental standards.
Solder with Pure Tin: Utilized in select applications, pure tin solder serves a niche role, especially in scenarios demanding high reliability connections with exacting purity standards.
Lead-Free Solder Paste: Lead-free solder pastes are commonly utilized for soldering surface-mount components, providing a convenient and effective method for achieving soldering without lead.
Soldering plays a vital role in the electronics industry. A critical decision in soldering is the choice of solder material. The debate between lead-based and lead-free solder continues, each presenting its own pros and cons. In this article, we'll compare these solder types in a concise table format, simplifying the understanding of differences and assisting in selecting the appropriate option for your needs.
| Attribute | Lead-based Solder | Lead-free Solder |
| Composition | A blend of lead and tin, usually containing a higher lead concentration, typically ranging from 40% to 60%. | Typically comprised of tin, silver, copper, antimony, etc., with minimal to no lead content. Prominent lead-free solders encompass tin-silver-copper (SAC) alloys or blends containing varying proportions of tin and copper. |
| Environmental Impact | Lead-containing solder can emit dangerous fumes while soldering, posing a risk of lead poisoning if mishandled. | Lead-free solder, without or with minimal lead content, is environmentally friendlier and has a lesser impact on both the environment and human health. |
| Soldering Performance | Generally demonstrates excellent fluidity and wetting properties, facilitating ease of use and enabling soldering at relatively low temperatures. | Lead-free solder typically requires a higher soldering temperature compared to lead-based solder. Nevertheless, its solder joint quality and mechanical characteristics can equal or even surpass those of lead-based solder. |
| Reliability | Because of its low melting point and favorable wetting properties, it might offer superior electrical connectivity under specific circumstances. | Because of the elevated soldering temperature, it typically provides enhanced solder joint strength and durability, particularly in high-temperature settings. |
How To Choose a Good Quality Solder?
Usually, premium solder consists of a tin-lead alloy. However, due to environmental considerations, certain solders opt for alternative alloys that don't contain lead. Ensure that the selected solder alloy exhibits excellent soldering characteristics and corrosion resistance.
The solder's diameter influences welding precision and control. Thinner solder is appropriate for intricate welding, while thicker solder is better suited for larger welding tasks. Select the solder diameter that aligns with your work requirements.
Solder typically falls into two categories: core-containing and core-less. Core-containing solder contains a flux core, offering improved soldering results, especially for workpieces with extensive surface oxidation. On the other hand, core-less solder is preferable for applications that require strict residue control.
Various solder types demand distinct soldering temperatures. Ensure that your solder can function within the temperature range specified by your soldering equipment and exhibits effective melting and flowing properties.
Take into account selecting solder that adheres to environmental guidelines, such as RoHS directives which limit the usage of harmful substances. These solder options not only promote environmental friendliness but also align with regulatory standards in your region.
Consider flux as a preparatory agent in the soldering procedure. When soldering two metal surfaces, it's crucial to establish a strong metallurgic bond to prevent the solder joint from loosening and to maintain consistent electrical continuity amidst mechanical, thermal, and other stresses. Flux serves to eliminate any oxidation present and lightly etches the surfaces to enhance wetting. "Wetting" denotes the solder's flow across the contact surfaces and the soldering tip, a pivotal aspect of the soldering process.
No-clean flux proves advantageous in soldering scenarios where cleaning is undesirable. Its minimal residue can either remain on the board or be eliminated using a flux remover. Rosin activated flux (RA) offers exceptional solderability across a broad range of applications. However, it's advisable to remove any residue post-soldering for aesthetic reasons and to prevent potential corrosion in the future. Rosin flux (R) or mildly activated rosin flux (RMA) typically can remain on the PCB after soldering, unless aesthetics are a concern. Water-soluble flux (OA) is a highly active flux designed for easy removal using deionized (DI) water, such as in a batch or in-line system, or with isopropyl alcohol (IPA). Thoroughly cleaning off water-soluble flux residues is crucial due to their high corrosiveness.
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