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- January 28, 2023
- PCB knowledge
- (0)
- 06 mins
Hot air solder leveling (HASL) – what is it used for
Are you interested in learning about a popular process used in circuit board fabrication? HASL is an important method of soldering integrated circuits and other components on printed circuit boards. As the name implies, it uses hot air to level out any imperfections on the surface of the printed circuit boards before they are put into use. In this article, we will provide an overview of what HASL is and its benefits so that you can better understand why it’s such a commonly used technology.
What does HASL stand for?
HASL stands for Hot Air Solder Leveling. It is an important process in the production of circuit boards.
What is HASL used for?
HASL is used to ensure that all components on a printed circuit board have even and complete coverage of solder. This ensures secure connections between components and proper electrical performance. It involves passing hot air across the board and melting the solder, ensuring it coats all parts evenly before it cools down. The result is a smooth finish with a maximum surface contact area that facilitates reliable electrical operation and a longer lifespan for the circuit boards.
What is a HASL PCB?
HASL PCBs are the most common type of circuit board used in the electronics industry due to their cost-effectiveness and ease of use. HASL is essentially a method of circuit board fabrication that consists of dipping the entire board into a bath of molten solder and then using hot air to level it off at specific heights. They are highly durable and can stand up to extreme temperatures as well as vibration and other stresses over time.
HASL is also great for soldering components with existing parts like leaded chipsets, providing consistent results with each iteration. The resulting boards offer reliable performance which makes them perfect for commercial applications.
Advantages and disadvantages of HASL PCB
Here are some advantages:
a. HASL provides good solderability
HASL provides good solderability due to the presence of lead in the alloy. The lead present in the alloy helps to wet the surface of the solder and provides a good connection between the two surfaces.
b. HASL is resistant to corrosion
HASL is resistant to corrosion due to the presence of lead in the alloy. Lead is a highly corrosion-resistant metal, which helps to protect the coating from corrosion.
c. HASL is inexpensive
HASL is an inexpensive coating material, which makes it an ideal choice for many applications.
Here are also some disadvantages:
a. Not as durable as other types of PCBs
HASL PCBs are not as durable as other types of PCBs. This means that they are more likely to break or be damaged over time.
b. HASL can be difficult to work with
HASL can be difficult to work with because it is a lead-based solder. Lead is a toxic metal that can be harmful to human health if it is inhaled or ingested. Additionally, lead can be difficult to remove from the body once it has been absorbed.
c. HASL may contain harmful chemicals
HASL may also contain harmful chemicals, such as tin and copper. These chemicals can be released into the environment when devices containing HASL are disposed of in landfills.
How is HASL applied on a PCB?
Hot-Air Solder Leveling covers printed circuit boards (PCBs) with molten alloy for the purpose of surface finishing. The alloy is melted and then evenly distributed over the PCB surface before it solidifies. The HASL layer ensures electrical connections are strong and reliable even when used in high-speed circuits.
During HASL application, a wave soldering machine heats the PCB to a pre-set temperature before releasing a stream of hot air from wave nozzles to further heat up the PCB’s entire surface. This melting point helps lubricate the solder joint between two separate components, forming an electrical bridge throughout the board by covering its traces with an even layer of solder alloy.
Is HASL finish RoHS compliant?
Yes, HASL is RoHS compliant. In recent years, manufacturers have been increasingly using HASL due to its compliance with RoHS (Restriction of Hazardous Substances). Its finish provides good soldering results while also meeting international standards for safe environmental use.
What is HASL with lead?
Lead-based HASL, otherwise known as Hot Air Solder Leveling with Lead, is a process where components with lead are exposed to hot air which forces out any excess solder and creates an even layer on the board’s surface. This technique is commonly used for printed circuit boards and other electronic components that require uniform joints to maximize their electronic efficacy.
HASL vs ENIG
Hot air solder leveling (HASL) is an inexpensive plating process that leaves a thick protective layer of solder over the board. On the other hand, electroless nickel immersion gold (ENIG) is more precise but more expensive. The main difference is that ENIG provides a thinner, higher-quality surface finish. It has excellent shelf life compared to HASL and can be helpful for multiple operations such as rework and sticker attachment.
HASL vs immersion silver
Hot Air Solder Leveling is achieved by running molten solder over the board while hot air is blown across its surface. Immersion silver is a coating consisting of a tin-silver alloy that is applied to the circuit board through electroless plating.
Both finishes offer excellent results when it comes to improving electrical connections on printed circuit boards but there are a few differences between them. HASL offers greater longevity and is better suited for use in applications with harsher environments; however, immersion silver provides superior soldering performance due to its higher reliability and higher thermal stability.
Which surface finish is best for PCB?
When selecting a surface finish for Printed Circuit Board (PCB) assemblies, hot air solder levelling (HASL) is by far the best option. It provides superior solder ability and electrical performance, making it the ideal choice for deep-finish printed circuit boards.
In addition to providing excellent protection against corrosion and heat resistivity, HASL also offers good thermal fatigue resistance and mechanical stability. With its many benefits, hot air solder levelling is the preferred surface finish for most PCB manufacturing processes.
HASL stands for Hot Air Solder Leveling. It is an important process in the production of circuit boards.
HASL is used to ensure that all components on a printed circuit board have even and complete coverage of solder. This ensures secure connections between components and proper electrical performance.
Yes, HASL is RoHS compliant. In recent years, manufacturers have been increasingly using HASL due to its compliance with RoHS (Restriction of Hazardous Substances). Its finish provides good soldering results while also meeting international standards for safe environmental use.
Conclusion
HASL is a process in which lead is added to solder in order to lower the melting point. This makes it easier to create reliable electrical connections between metals. It is also used for its bright and shiny finish, making it a popular choice for printed circuit boards. However, there are some disadvantages to using it, such as its tendency to corrode over time. If you’re looking for a durable and long-lasting surface finish for your PCB, it may not be the best option.
