What is HASL? What is the difference between lead-free ...

The surface treatment of PCB striking board includes OSP, gold precipitation, bare copper, Hard zinc plating, and the most common HASL.

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HASL can be divided into lead-free HASL and lead HASL. These surface treatments can be done by deep sub electrons.

First, let&#;s learn about HASL:

Hot air solder leveling is a step and process flow in the production process of PCB. Specifically, immerse the PCB into the molten solder pool, so that all exposed copper surfaces will be covered by solder, and then remove the excess solder on the PCB through a hot-air cutter [2]. Because the surface of the circuit board after tin spraying is the same material as the solder paste, the welding strength and reliability are good. However, due to its processing characteristics, the surface flatness of tin spraying treatment is not good, especially for small electronic components such as BGA. Due to the small welding area, if the flatness is poor, it may cause problems such as short circuit. Therefore, a process with good flatness is required to solve the problem of tin spraying plate. Generally, the gold plating process (not the gold plating process) will be selected, and the principle and method of chemical replacement reaction will be used for reprocessing to increase the nickel layer with a thickness of about 0.03~0.05um or 6um to improve the surface flatness.

Product advantages:

1. The wettability of components and parts during welding is good, and it is easier to solder.

2. The exposed copper surface can be prevented from being corroded or oxidized.

Product disadvantages:

1. The flatness of the vertical layer is poor, which is not suitable for the welding and use of components with fine spacing. The flatness can be improved by adding a horizontal layer.

2. The high thermal stress during the treatment may damage the PCB and cause defects or defects.

So let&#;s focus on explaining the difference between lead-free tin spraying and lead tin spraying?

1. From the surface of tin, lead tin is bright, while lead-free tin (SAC) is dim. The wettability of lead-free is less than that of lead-free,

2. Lead in lead is harmful to human body, while lead-free does not. The eutectic temperature with lead is lower than that without lead. The specific amount depends on the composition of the lead-free alloy. For example, the eutectic temperature of SnAgCu is 217 degrees, and the welding temperature is the eutectic temperature plus 30~50 degrees. It depends on the actual adjustment. The eutectic with lead is 183 degrees. Mechanical strength, brightness, etc. lead is better than lead-free.

3. The lead content of lead-free tin shall not exceed 0.5, and that of lead containing tin shall reach 37.

4. Lead will improve the activity of tin wire in the welding process. Lead tin wire is relatively easier to use than lead-free tin wire. However, lead is toxic, and long-term use is bad for human body. In addition, lead-free tin will have a higher melting point than lead tin wire, so the welding point is much stronger.

5. Lead will increase the activity of tin in the welding process. Lead tin wire is better to use than lead-free tin wire, and lead-free tin spraying has a higher melting point than lead tin spraying, and the welding points will be much stronger.

6. The price of lead-free tin spraying and lead tin spraying for PCB proofing is the same, there is no difference.

Contact us to discuss your requirements of lead-free hasl. Our experienced sales team can help you identify the options that best suit your needs.

*Note &#; it is generally agreed that all of these SnAgCu alloys melt at ˜217°C, but published melting range for each alloy varies; the indicated melting range is estimated from NIST phase diagram; in any case NIST determined there will be =0.1% solid material in any of these alloys at 220°C.

The NEMI consortium in USA recommends SnAg3.9Cu0.6 for surface mount reflow soldering and SnCu0.7 for wave soldering. The JEITA lead-free roadmap in Japan recommends SnAg3.0Cu0.5 for reflow soldering with SnAg and SnZnBi as secondary alternatives. JEITA also recommends SnAg3.0Cu0.5 for wave soldering with SnCu as a secondary alternative. The IDEALS consortium in Europe preferred SnAg3.8Cu0.7 for reflow soldering and SnAg3.8Cu0.7Sb0.25 for wave soldering. SOLDERTEC lead-free roadmap in Europe recommends alloy range SnAg(3.4-4.1)Cu(0.45-0.9) for reflow and wave soldering.The SnAgCu family is the alloy of choice for all regions of the world at present. The true eutectic composition has been argued to be within the range SnAg(3.5-3.8)Cu(0.7-1). NIST has defined the true eutectic composition as SnAg3.5Cu0.9 .In Japan 2/3 of companies use SnAgCu for reflow and wave soldering. For surface mount reflow SnAg, SnZnBi, SnAgCuBi and SnInAgBi are also used to a lesser degree. For wave soldering SnCu and SnAg are also used to a lesser degree. About 3/4 of companies use SnAgCu for hand soldering. The predominant SnAgCu alloy in use in Japan is SnAg3.0Cu0.5 and increasing trend elsewhere as well. Kester is a licensee of ISURF SnAgCu(Bi) patent 5,527,628, Senju-Matsushita SnAgCu(Bi) patent and Oatey SnAgBiCu patent 4,879,096. Below is a reference listing of Pb-free alloys in order of melting point. It is not meant to be an exhaustive list and is not meant to preclude the potential use of other alloys.

Lead-Free Reflow Profile Recommended reflow profile for Kester solder paste formulations containing the Sn96.5Ag3.5 and Sn96.5Ag3.0Cu0.5 alloys
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K100LD & K100 Case Studies Summary This PowerPoint pictorial examines a successful implementation of K100LD and K100 lead-free alloys at SMT Dynamics and Ayrshire Electronics.
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Standard Reflow Profile The recommended reflow profile for Kester solder pastes manufactured with standard tin/lead alloys.
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K100 Implementation at SMT Dynamics This paper shows results obtained at a contractor in successful builds using SAC305 for reflow soldering and K100 solder for wave assembly.
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Developing a Reliable Lead-free SMT Assembly Process This article offers valuable information to be used during the successful lead-free reflow process implementation.
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How do you create a RoHS Compliancy-Lead-free Roadmap? This article describes the various considerations in the transition to lead-free but also RoHS comnpliancy.
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How do you ready a solder pot for lead-free solder? This article in designed for those cleaning a leaded solder pot to convert it to lead-free solder. It insures the solder is not contaminated with lead during the switchover.
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Implementation of Reliable Lead-free Wave and SMT Processes This article describes the points to consider in transitioning to lead-free wave and reflow soldering.
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Lead-free Hand-soldering &#; Ending the Nightmares Hand-soldering with lead-free solders can be challenging but not if the points in this article are understood.
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Lead-free Reliability &#; Building it right the First Time This article describes the comparison done in reference to lead-free and leaded solder joints. The article also gives insight on the points to improve overall reliability with lead-free solders.
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Lead-free SMT Soldering Defects How to Prevent Them This paper shows how avoid soldering defects with lead-free solder pastes. Process control is emphasized to reduce defects.
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Lead-free Wave Soldering This article shows the impact to wave soldering with lead-free materials and how to create a reliable defect free process.
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Creating Solder Joint Reliability with SnCu Based Solders Tin-copper systems with lead-free wave and selective soldering are a growing option. This paper shows how to implement a reliable process using K100 or K100LD SnCu based solders.
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Tin-copper based solder options for lead-free assembly This article details the process changes associated with K100 or K100LD solder systems.
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Case Study on the Validation of SAC305 and SnCu Based Solders in SMT Wave and Hand-soldering This paper describes the work done at a contract assembler who implemented a successful process to build over 500,000 assemblies using both Kester K100 and SAC305 solders.
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