The Premium & Affordable HASL PCB Supplier
We provide you with the ever-affordable HASL PCB on short notice.
- We’re the best one-stop shop for PCB manufacturing
- Sales and technical tech support are available 24 hours a day, all days of the week
- We customize PCB designs to your product specifications.
- Quality Control and Quality Checks – 100%
Only trust the PCB leader in Shenzhen for your safety and convenience.
The Popular Surface Finish: HASL
We provide a wide range of HASL PCB items to assist you with your project and business needs.
HASL PCB is compliant with most requirements for military-grade PCBs.
Although not the one sought after for the highest performing HDI boards, it is still a relevant option.
We have over 12 years of manufacturing experience, consequently trust not mess up your order.
Contact us for more details.
The application of HASL PCB surface finish strikes proper balance in costing.
Kindly view this page for all vital information.
HASL PCB By Feature
The HDI HASL PCB is not a common request. Mostly, HDI boards are designated to ENIG PCB category or ENEPIG.
As the FR4 is compatible to HASL, it is the go-to PCB material. This results in FR4 HASL PCB, which has medium cost.
For customers using PCBs with prolonged exposure to harsh elements, Rigid HASL PCB is recommended.
The High Frequency range is not particularly suited for HASL, nevertheless, some customers insist on it for budget reasons.
If compliances to RoHS is your problem, then Lead-free HASL PCB is your solution. It’s safely toxin-free.
A temperature range of 130 degrees Celsius is the norm. But High Tg HASL PCB can take 170 Celsius and 180 too.
HASL PCB By Type (6)
For Buried Via PCB, this typical board is multilayer. The dedicated holes are drilled down with laser tools.
When you use a Blind Via HASL PCB, you may be sure that the inner layers of the PCBs are well connected and secure.
If SMT is not available, the Through Hole technique is employed. Resistors and capacitors are attached here.
When prototyping a PCB, PTH HASL PCB or Through Hole PCB is still used. We provide a service called Through Hole Assembly too.
Please contact us if you require a different Surface Finish PCB. Aside from Surface Finish HASL PCB, we can also include Immersion Tin.
Silkscreen HASL PCB ink is often epoxy-based. For this reason, we stock Taiyo Ink PCBs. It is a low CTE product that is entirely suitable.
HASL PCB By Layer (5)
Single-Layer PCB cannot compete with the variety of multilayer PCBs, but it outfits small appliances well.
If you want to go beyond single-layer PCB designs, you can use double-layer PCB. But it increases your electrical connections in a limited way.
You can’t go wrong with a multilayer PCB. Renowned computer brands utilize them as well, when they purchase from PCBTok as their OEM.
Because of the extensive use of telecom devices, high layer counts like the 20 Layer PCB is becoming increasingly crucial and much wanted.
If you consider efficient PCB stack-up design, a 30 Layer PCB is achievable as well as economical. It is also significant for home devices.
No Other HASL PCB Can Compare
We supply first-rate HASL PCB and PCB assembly services.
For your purchase sample, you will receive a COC report, a micro-section, and soldering sample too, if desired.
We have technical expertise because we employ over 500 professionals.
They will keep track of your orders to ensure that the HASL PCB you receive is error-free.
With our built-in knowledge, your product will be first-rate.
Right PCB Inspections & Care
We want you to be at ease before we begin our HASL transaction.
In terms of payment, we want you to feel like you got a fair price.
Our terms are flexible and adjustable.
Another factor that sets us apart from other inferior HASL PCB manufacturers is that we have Engineering and QC inspections.
Experts are available to support you around the clock—and speak English fluently.
Likewise, we are OK with factory and third party audits.
Best HASL PCB at a Minimal Cost
We must be perfect as your HASL PCB maker, avoiding complications at all costs.
We’re here to help you make the most of the money you have available.
The constant monitoring of the HASL PCB process is required to avoid errors along the route.
Manufacturing errors are expensive and should never happen in the first place.
We provide sample products, as this is common with prototype PCBs and high volume HASL PCB sales.
PCBTok is the Right HASL PCB Manufacturer for You
If you work in the Semiconductor Sector, PCBTok’s HASL PCB is ideal.
Because of its inherent stability, it is a versatile product with many applications.
It is also quite long-lasting, as it is time-tested.
There is a significant need for multilayer PCBs that are as affordable as the HASL PCB.
Mass production is standard at our factory.
We guarantee that there will be no PCB supply shortages.
HASL PCB Fabrication
If you are thinking of being the best in your industry, then you need to be smart.
Even though we promise the lowest prices, you can be confident that it is the industry standard.
The HASL PCB we have will withstand the test of time.
They will cut your costs to maximize your profit—
So you can be the best among your opponents in the electronics market.
Inquire now to avail!
HDI and High Frequency PCBs allow for the installation of complex PCB components.
HASL, on the other hand, specializes in lower pitch multilayer products as well as the single-sided/double-sided products.
The biggest feature of HASL is its wettability, which is why it is sometimes favored over ENIG—
ENIG is the most popular surface finish in recent years.
HASL PCB contains lead at 37 percent, with a 63/37 ratio.
But we promise to use it in the safest situation possible.
OEM & ODM HASL PCB Applications
One of our hottest sellers is HASL PCB for Communication Applications. Customers in this area are increasing as the mobile communication industry grows organically.
If everyone has a laptop/tablet, then everyone has heard of a HASL PCB for laptops/tablets. The same holds true for every computer device.
HASL PCB for Medical Equipment is used in cautery equipment, cytology equipment, laryngoscopes, and cardiotocographs.
HASL PCB is frequently used in digital consumer electronics. The HASL PCB is compatible with a broad range of 5G, wireless, and mobile phones.
Motor controllers, encoders, DC motor peripherals, and the rest are examples of HASL PCB applied on industrial usage.
HASL PCB Production Details As Following Up
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|1||Layer Count||1-20 layers||22-40 layer|
|2||Base Material||KB、Shengyi、ShengyiSF305、FR408、FR408HR、IS410、FR406、GETEK、370HR、IT180A、Rogers4350、Rogers400、PTFE Laminates(Rogers series、Taconic series、Arlon series、Nelco series)、Rogers/Taconic/Arlon/Nelco laminate with FR-4 material(including partial Ro4350B hybrid laminating with FR-4)|
|3||PCB Type||Rigid PCB/FPC/Flex-Rigid||Backplane、HDI、High multi-layer blind&buried PCB、Embedded Capacitance、Embedded resistance board 、Heavy copper power PCB、Backdrill.|
|4||Lamination type||Blind&buried via type||Mechanical blind&burried vias with less than 3 times laminating||Mechanical blind&burried vias with less than 2 times laminating|
|HDI PCB||1+n+1,1+1+n+1+1,2+n+2,3+n+3(n buried vias≤0.3mm),Laser blind via can be filling plating||1+n+1,1+1+n+1+1,2+n+2,3+n+3(n buried vias≤0.3mm),Laser blind via can be filling plating|
|5||Finished Board Thickness||0.2-3.2mm||3.4-7mm|
|6||Minimum Core Thickness||0.15mm(6mil)||0.1mm(4mil)|
|7||Copper Thickness||Min. 1/2 OZ, Max. 4 OZ||Min. 1/3 OZ, Max. 10 OZ|
|9||Maximum Board Size||500*600mm(19”*23”)||1100*500mm(43”*19”)|
|10||Hole||Min laser drilling size||4mil||4mil|
|Max laser drilling size||6mil||6mil|
|Max aspect ratio for Hole plate||10:1（hole diameter＞8mil）||20:1|
|Max aspect ratio for laser via filling plating||0.9:1(Depth included copper thickness)||1:1(Depth included copper thickness)|
|Max aspect ratio for mechanical depth-
control drilling board(Blind hole drilling depth/blind hole size)
|0.8:1(drilling tool size≥10mil)||1.3:1(drilling tool size≤8mil),1.15:1(drilling tool size≥10mil)|
|Min. depth of Mechanical depth-control(back drill)||8mil||8mil|
|Min gap between hole wall and
conductor (None blind and buried via PCB)
|Min gap between hole wall conductor (Blind and buried via PCB)||8mil(1 times laminating),10mil(2 times laminating), 12mil(3 times laminating)||7mil(1 time laminating), 8mil(2 times laminating), 9mil(3 times laminating)|
|Min gab between hole wall conductor(Laser blind hole buried via PCB)||7mil（1+N+1）；8mil（1+1+N+1+1 or 2+N+2）||7mil（1+N+1）；8mil（1+1+N+1+1 or 2+N+2）|
|Min space between laser holes and conductor||6mil||5mil|
|Min space between hole walls in different net||10mil||10mil|
|Min space between hole walls in the same net||6mil(thru-hole& laser hole PCB),10mil(Mechanical blind&buried PCB)||6mil(thru-hole& laser hole PCB),10mil(Mechanical blind&buried PCB)|
|Min space bwteen NPTH hole walls||8mil||8mil|
|Hole location tolerance||±2mil||±2mil|
|Pressfit holes tolerance||±2mil||±2mil|
|Countersink depth tolerance||±6mil||±6mil|
|Countersink hole size tolerance||±6mil||±6mil|
|11||Pad(ring)||Min Pad size for laser drillings||10mil(for 4mil laser via),11mil(for 5mil laser via)||10mil(for 4mil laser via),11mil(for 5mil laser via)|
|Min Pad size for mechanical drillings||16mil(8mil drillings)||16mil(8mil drillings)|
|Min BGA pad size||HASL:10mil, LF HASL:12mil, other surface technics are 10mil(7mil is ok for flash gold)||HASL:10mil, LF HASL:12mil, other surface technics are 7mi|
|Pad size tolerance(BGA)||±1.5mil(pad size≤10mil);±15%(pad size>10mil)||±1.2mil(pad size≤12mil);±10%(pad size≥12mil)|
|1OZ: 3/4mil||1OZ: 3/4mil|
|2OZ: 4/5.5mil||2OZ: 4/5mil|
|3OZ: 5/8mil||3OZ: 5/8mil|
|4OZ: 6/11mil||4OZ: 6/11mil|
|5OZ: 7/14mil||5OZ: 7/13.5mil|
|6OZ: 8/16mil||6OZ: 8/15mil|
|7OZ: 9/19mil||7OZ: 9/18mil|
|8OZ: 10/22mil||8OZ: 10/21mil|
|9OZ: 11/25mil||9OZ: 11/24mil|
|10OZ: 12/28mil||10OZ: 12/27mil|
|1OZ: 4.8/5mil||1OZ: 4.5/5mil|
|1.43OZ（negative ）:5/8||1.43OZ（negative ）:5/7|
|2OZ: 6/8mil||2OZ: 6/7mil|
|3OZ: 6/12mil||3OZ: 6/10mil|
|4OZ: 7.5/15mil||4OZ: 7.5/13mil|
|5OZ: 9/18mil||5OZ: 9/16mil|
|6OZ: 10/21mil||6OZ: 10/19mil|
|7OZ: 11/25mil||7OZ: 11/22mil|
|8OZ: 12/29mil||8OZ: 12/26mil|
|9OZ: 13/33mil||9OZ: 13/30mil|
|10OZ: 14/38mil||10OZ: 14/35mil|
|13||Dimension Tolerance||Hole Position||0.08 ( 3 mils)|
|Conductor Width(W)||20% Deviation of Master
|1mil Deviation of Master
|Outline Dimension||0.15 mm ( 6 mils)||0.10 mm ( 4 mils)|
|Conductors & Outline
( C – O )
|0.15 mm ( 6 mils)||0.13 mm ( 5 mils)|
|Warp and Twist||0.75%||0.50%|
|14||Solder Mask||Max drilling tool size for via filled with Soldermask (single side)||35.4mil||35.4mil|
|Soldermask color||Green, Black, Blue, Red, White, Yellow,Purple matte/glossy|
|Silkscreen color||White, Black,Blue,Yellow|
|Max hole size for via filled with Blue glue aluminium||197mil||197mil|
|Finish hole size for via filled with resin||4-25.4mil||4-25.4mil|
|Max aspect ratio for via filled with resin board||8:1||12:1|
|Min width of soldermask bridge||Base copper≤0.5 oz、Immersion Tin： 7.5mil(Black), 5.5mil(Other color) , 8mil( on copper area)|
|Base copper≤0.5 oz、Finish treatment not Immersion Tin ： 5.5 mil(Black,extremity 5mil), 4mil(Other
color,extremity 3.5mil) , 8mil( on copper area
|Base coppe 1 oz: 4mil(Green), 5mil(Other color) , 5.5mil(Black,extremity 5mil),8mil( on copper area)|
|Base copper 1.43 oz: 4mil(Green), 5.5mil(Other color) , 6mil(Black), 8mil( on copper area)|
|Base copper 2 oz-4 oz: 6mil, 8mil( on copper area)|
|15||Surface Treatment||Lead free||Flash gold(electroplated gold)、ENIG、Hard gold、Flash gold、HASL Lead free、OSP、ENEPIG、Soft gold、Immersion silver、Immersion Tin、ENIG+OSP,ENIG+Gold finger,Flash gold(electroplated gold)+Gold finger,Immersion silver+Gold finger,Immersion Tin+Gold finge|
|Aspect ratio||10:1(HASL Lead free、HASL Lead、ENIG、Immersion Tin、Immersion silver、ENEPIG);8:1(OSP)|
|Max finished size||HASL Lead 22″*39″；HASL Lead free 22″*24″；Flash gold 24″*24″；Hard gold 24″*28″；ENIG 21″*27″；Flash gold(electroplated gold) 21″*48″；Immersion Tin 16″*21″；Immersion silver 16″*18″；OSP 24″*40″；|
|Min finished size||HASL Lead 5″*6″；HASL Lead free 10″*10″；Flash gold 12″*16″；Hard gold 3″*3″；Flash gold(electroplated gold) 8″*10″；Immersion Tin 2″*4″；Immersion silver 2″*4″；OSP 2″*2″；|
|PCB thickness||HASL Lead 0.6-4.0mm；HASL Lead free 0.6-4.0mm；Flash gold 1.0-3.2mm；Hard gold 0.1-5.0mm；ENIG 0.2-7.0mm；Flash gold(electroplated gold) 0.15-5.0mm；Immersion Tin 0.4-5.0mm；Immersion silver 0.4-5.0mm；OSP 0.2-6.0mm|
|Max high to gold finger||1.5inch|
|Min space between gold fingers||6mil|
|Min block space to gold fingers||7.5mil|
|16||V-Cutting||Panel Size||500mm X 622 mm ( max. )||500mm X 800 mm ( max. )|
|Board Thickness||0.50 mm (20mil) min.||0.30 mm (12mil) min.|
|Remain Thickness||1/3 board thickness||0.40 +/-0.10mm( 16+/-4 mil )|
|Tolerance||±0.13 mm(5mil)||±0.1 mm(4mil)|
|Groove Width||0.50 mm (20mil) max.||0.38 mm (15mil) max.|
|Groove to Groove||20 mm (787mil) min.||10 mm (394mil) min.|
|Groove to Trace||0.45 mm(18mil) min.||0.38 mm(15mil) min.|
|17||Slot||Slot size tol.L≥2W||PTH Slot: L：+/-0.13(5mil) W：+/-0.08(3mil)||PTH Slot: L：+/-0.10(4mil) W：+/-0.05(2mil)|
|NPTH slot(mm) L+/-0.10 (4mil) W：+/-0.05(2mil)||NPTH slot(mm) L：+/-0.08 (3mil) W：+/-0.05(2mil)|
|18||Min Spacing from hole edge to hole edge||0.30-1.60 (Hole Diameter)||0.15mm(6mil)||0.10mm(4mil)|
|1.61-6.50 (Hole Diameter)||0.15mm(6mil)||0.13mm(5mil)|
|19||Min spacing between hole edge to circuitry pattern||PTH hole: 0.20mm(8mil)||PTH hole: 0.13mm(5mil)|
|NPTH hole: 0.18mm(7mil)||NPTH hole: 0.10mm(4mil)|
|20||Image transfer Registration tol||Circuit pattern vs.index hole||0.10(4mil)||0.08(3mil)|
|Circuit pattern vs.2nd drill hole||0.15(6mil)||0.10(4mil)|
|21||Registration tolerance of front/back image||0.075mm(3mil)||0.05mm(2mil)|
|22||Multilayers||Layer-layer misregistration||4layers:||0.15mm(6mil)max.||4layers:||0.10mm(4mil) max.|
|Min. Spacing from Hole Edge to Innerlayer Pattern||0.225mm(9mil)||0.15mm(6mil)|
|Min.Spacing from Outline to Innerlayer Pattern||0.38mm(15mil)||0.225mm(9mil)|
|Min. board thickness||4layers:0.30mm(12mil)||4layers:0.20mm(8mil)|
|Board thickness tolerance||4layers:+/-0.13mm(5mil)||4layers:+/-0.10mm(4mil)|
|8-12 layers:+/-0.20mm (8mil)||8-12 layers:+/-0.15mm (6mil)|
|26||Impedance control||±5ohm(＜50ohm), ±10%(≥50ohm)|
PCBTok offers flexible shipping methods for our customers, you may choose from one of the methods below.
DHL offers international express services in over 220 countries.
DHL partners with PCBTok and offers very competitive rates to customers of PCBTok.
It normally takes 3-7 business days for the package to be delivered around the world.
UPS gets the facts and figures about the world’s largest package delivery company and one of the leading global providers of specialized transportation and logistics services.
It normally takes 3-7 business days to deliver a package to most of the addresses in the world.
TNT has 56,000 employees in 61 countries.
It takes 4-9 business days to deliver the packages to the hands
of our customers.
FedEx offers delivery solutions for customers around the world.
It takes 4-7 business days to deliver the packages to the hands
of our customers.
5. Air, Sea/Air, and Sea
If your order is of large volume with PCBTok, you can also choose
to ship via air, sea/air combined, and sea when necessary.
Please contact your sales representative for shipping solutions.
Note: if you need others, please contact your sales representative for shipping solutions.
You can use the following payment methods:
Telegraphic Transfer(TT): A telegraphic transfer (TT) is an electronic method of transferring funds utilized primarily for overseas wire transactions. It’s very convenient to transfer.
Bank/Wire transfer: To pay by wire transfer using your bank account, you need to visit your nearest bank branch with the wire transfer information. Your payment will be completed 3-5 business days after you have finished the money transfer.
Paypal: Pay easily, fast and secure with PayPal. many other credit and debit cards via PayPal.
Credit Card: You can pay with a credit card: Visa, Visa Electron, MasterCard, Maestro.
“In comparison to other Chinese providers, PCBTok completed the project in a day, with exceptional customer service and at a lower cost. We are quite pleased with the rapid and effective service done by these people. Salesperson “H” was really quite polite. The PCBA service was prompt and thorough, and he explained the problem and answered all of my questions. Completely referable! Congratulations on your achievement.”Gustavo Gabillet, PCB Inspector & Entrepreneur from Dublin, Ireland
“I’ve never worked with a PCB provider who was more professional and easy to work with. This team is extremely savvy, straightforward, communicative, and affordable. They responded immediately after I messaged their website. Not only that, but they were able to maintain constant communication with me over the next four hours as we worked out the details.”Ludwig Rieth, Computer Hardware Specialist from Grande do Sul, Brazil
“This company means business. PCBTok engineers are very professional and performed an amazing job with my HASL and Lead-free HASL PCB high volume order. I needed to be stern with WEEE guide lines at the time. They stated that they could assist, and they did. Furthermore, the guys completed sooner than planned. I was overjoyed they have finished the work fast.”Dirk Kormákur, Procurement Director from Blue Lagoon, Iceland
HASL PCB: The Ultimate FAQ Guide
HASL stands for hot-air-solder-level and is a process in which a layer of solder is applied to a PCB. In this process, the PCB is heated to 265 degrees Celsius to detect delamination and other problems that could lead to poor board molding. Dip tin (a metal finish that protects the copper from oxidation) is then applied to the surface.
At one time, HASL was the industry standard for circuit boards. This was accomplished by dipping the board into molten solder and then blowing away the excess with an “air knife”. HASL forms a thin coating that protects the copper from oxidation and improves solderability. The PCB must absorb the melted solder and have good pad wetting and copper coverage to achieve a successful HASL.
The power layer, signal layer, and bottom overlay are the layers that make up the PCB. Separators must be used to separate each layer. Typically, these layers are parallel to each other. Also, low-speed signals must be connected to the power layer. Therefore, the power plane layer must be linked to the low-speed signal layer. In some cases, additional signal layers are added. A GND auxiliary layer can be included on the final PCB to act as a shield for the high-speed signals.
Hot Air Soldering Level (HASL) is the most common surface treatment for copper on PCBs. In this process, the copper is coated with solder. The board is then immersed in a pot of solder. The excess solder is then blown away. HASL, which has been around since the 1970s, is hard to screw up.
Common surface treatment on PCBs is hot air solder leveling (HASL). HASL is a lead-free solder alloy consisting of 63% tin and 37% lead. Lead-free PCBs are also an option. The technique involves immersing the board in a molten alloy and then removing excess solder with a hot air knife.
Double-Sided HASL PCB Sample
HASL has been a popular surface treatment for decades, but it has its drawbacks. It was reasonably priced and durable but was found to be unsuitable for fine-pitch assemblies. While HASL can be lead-free, if your product requires high reliability and quality, you should consider other lead-free finishes. This article explores the use of HASL in PCB manufacturing.
The most common PCB surface finish is HASL. it is also the most affordable. It is suitable for through-hole and a wide range of SMT components. It is also suitable for tight tolerances. However, it does not last as long as HASL. It is also more susceptible to oxidation. If you want to use OSP on PCBs, you should use a lead-free PCB surface treatment.
While HASL is still widely used, ENIG is often preferred in many applications. the process is characterized by a smooth, skinless surface finish. ENIG requires additional information about the solder atmosphere, such as temperature, humidity, and condensing atmosphere, which is critical to the finished product. Both procedures are effective and advantageous, but the latter is usually preferred in most cases.
ENIG has many advantages over HASL. It has excellent corrosion resistance and is recommended for applications requiring excellent adhesion to components. It also has good solderability and long shelf life. ENIG is more expensive than HASL, but it offers excellent performance in many applications. It is suitable for fine-pitch technology as well as aluminum wire bonding. It is also very good for the environment.
ENIG is an excellent choice for phosphorus corrosion-resistant applications. Its gold anvil construction is also popular in telecommunications and printing. ENIG also offers excellent surface finishes, making it the plating of choice for telecom and printer equipment. While ENIG is not as adaptable as HASL, it offers some distinct advantages. More information on ENIG can be found in the comparison table below.
ENIG PCB Sample
Both HASL and ENIG have advantages and disadvantages. HASL is more expensive and does not work to tight tolerances, while ENIG has excellent flatness and high solder resistance. ENIG may be a better choice than HASL when it comes to protecting copper wire. ENIG will allow you to solder components faster.
If you want to add a lead-free finish to your PCB, then you’re in luck. HASL (Hot Air Solder Levels) solders are made from lead-free alloys. Because they are safer to use and do not lead to lead buildup, these alloys are better for the environment than tin-lead alloys. The board is then wetted with solder and scraped off with an air knife set at a temperature above the melting point of the solder. The board is then cleaned to remove any flux and HASL is now ready for use.
The main difference between ENIG and HASL finishes is the metal used in the coating and the quality of the surface finish. While HASL is cheaper than ENIG, it may not meet the same quality standards. The cost of manufacturing the PCB is another factor that affects the cost of the finish. Some PCBs are more expensive than others, and you may want to use more expensive finishes on your consumer electronics PCBs.
Multilayer HASL PCB Sample
What is the difference between HASL lead-free finishes and lead-free solder? Tin-lead and lead-free HASL coatings have different solder coating thicknesses. Lead-free HASL is typically thinner than tin-lead HASL and has good coplanarity. It is critical to research PCB finishes before choosing one over the other.
While hot air solder leveling has many advantages, it also has some significant disadvantages. In the world of Six Sigma processes, it is considered a One Sigma process and its inconsistency is a significant drawback. Not only does hot air solder leveling not produce uniform thickness across the panel, but it also causes stress and fatigue on copper plating and printed circuit boards.
One of the most significant drawbacks of lead-based soldering is the limited use of lead, which must be phased out by the end of 2007. In addition, fine-pitch components may have uneven surfaces, which can lead to thickness problems and solder bridging. These problems can jeopardize the final assembly process. While hot air solder leveling has several advantages, it should be noted that it does not apply to all applications.
HASL allows a uniform layer of solder to be applied to the bare copper on the printed circuit board. However, after hot air leveling, a thin layer of solder remains on the bare copper. As a result, it does not provide sufficient protection for the wire-side edges, but it does improve reliability and extend the storage time of the printed board. Hot air solder leveling is a common SMT process.
Lead-free solder spray is the most common type of hot air soldering. Lead-free HASL contains 0.6% copper and 99.3% tin, which is much higher than lead-free solder but still requires modifications to the reflow process. Hot air solder leveling is an inexpensive PCB surface treatment with a long shelf life.