Why Immersion silver becauses PCB's new surface choice recently?
Just spray a layer of soaked silver on the printed circuit board to make everything “really flow” on the circuit board. As we all know, silver is the most conductive metal. Therefore, with the demand in the field of 5g circuit board, it will be used more and more.
Silver has better conductivity than gold or copper. It also has the advantage of easy welding surface modification, because the thickness of silver can be as small as 0.1 micron. Smaller thickness can also make the circuit board have better flatness – so it is suitable for higher structural levels with thinner links and gaps.
The new surface modification provides the greatest use where high-frequency signals need to be transmitted. Compared with ENIG or ENEPIG technology, it does not contain nickel layer. The quality of nickel layer leads to the complete reduction of power for higher frequency data transmission.
Immersion pcb application
If the PCB has a connection function requirement and needs to reduce cost, immersed silver is a good choice; coupled with the good flatness and contact properties of immersed silver, the immersed silver process should be chosen.
In communication products, automotive, computer peripherals, and high-speed signal design area Immersion silver has many applications. Because Immersion silver has good electrical properties that other surface treatments can’t catch, it can also be used for high frequency signals.
EMS recommends the use of the immersed silver process because it is easy to assemble and has good inspectability. Currently about 10-15% of PCBs use the silver-sink process.
Comon problem for Immersion pcb and how to solve
Cause of contamination of bare copper: glue, grease improvement methods:
1. Avoid putting glue strips on the board surface and use clean rubber spacers for each process; 2. Clean equipment (such as brewer, E-TEST) before making silver-sink PCB; 3. Soak the board with degumming water before dipping silver.
Causes of silver surface oxidation:
1. Staying in the air for too long;
2. Silver surface is contaminated and come in to contact with sulfur-containing substances. Improvement methods: 1. Immersion silver PCB must be packaged by vacuum bags within 8 hours;
3. Strengthen the training of operators and standardize the operation.
Venture Immersion Silver PCB is also known as immersion Ag. Immersion Silver PCB is RoHS compliant and standard finish at Pandawill Circuits.
Venture Immersion Silver PCB is an improvement on HASL being exceptionally flat. They can replace Immersion Gold over Electroless Nickel for most applications. Our Immersion Silver PCB has no effect on customer’s assembly processes.
Your Leading Immersion Silver PCB Supplier in China
Venture Electronics is the perfect place for Immersion Silver PCB for your project. We have been in this field for more than 10 years.
Venture immersion silver PCB describes a lead-free layer of silver-plated onto a PCB. We design immersion silver PCB to protect copper traces from corrosion.
Our immersion silver PCB has excellent solderability when compared to solder plating, accommodating a risk-free and straightforward PCB Assembly Process.
Venture immersion silver finish is gaining popularity in PCB designs through its beneficial features:
- environment friendly and RoHS compliant finish
- have better resistance to environmental aging
- has a capability to survive multiple reflows
- has better electrical properties, flatness, and solder joint strength
The immersion silver finish boasts a moderately long shelf life compared to other finishes such as Enig finishes. However, it is the best choice due to the fact that silver is the most electrically conductive metal available.
For that reason, our immersion silver is ideal for high-speed PCB applications. Silver surface finishes can be applied to copper traces with an electroless immersion reaction, displacing the copper layer.
Throughout the years, immersion silver PCB design team is expert in handling and storing of immersion silver-finished:
- They use gloves for handling panels or board to avoid finger contact with the immersion silver finish.
- The generally accepted shelf storage life for Immersion Silver is 6 to 12 months in dry conditions, the same as that for HASL.
- If PCBs have been in storage for some time, it is wise to perform a solderability test prior to assembly.
Moreover, Venture immersion silver holds sure cons and pros compared to other surface finish. In some cases, it is considered as a better surface finish.
At Venture, we have a wide range of surface finish available for PCBs. Venture Electronics can give you a total solution for your immersion silver PCB requirements.
As a reliable manufacturer, we can always meet your needs! We offer immersion silver PCB layouts, prototypes, design, and assembly. we have more than 10 years in this field.
Together with our professional team and design engineers, we make sure you have a great and high-quality design of the final immersion silver PCB products.
We are looking forward to local business partners throughout the world. Come to Venture Electronics and check out the details if you are interested.
For more information on our immersion silver PCB, or for any queries related to PCB design and manufacturing, you can contact our experts right away!
Immersion Silver PCB-The Ultimate FAQ Guide
If you have any question about immersion silver PCB, your answer is right here.
Keep reading to learn more.
- What is Immersion Silver Finish?
- How is Immersion Silver PCB Produced?
- What is Immersion Silver Plating?
- What are the Advantages of Immersion Silver PCBs?
- What are the Disadvantages of Immersion Silver PCB?
- What is Immersion Silver PCB Tarnish?
- What is the Process involved in Immersion Silver PCB?
- How long can Immersion Silver PCB last before it is used?
- How does Immersion Silver PCB compare to Immersion Gold PCB?
- How can you Handle and Store Immersion Silver Finish Products?
- What are the Specifications of the Immersion Silver PCB?
- What is involved in the Immersion Silver PCB Assembly?
- What is Immersion Silver PCB RoHS Finish?
- What is the Benefit of using Sterling in Immersion Silver Surface Finish?
- What are the Common Problems when using an Immersion Silver Finish? And, how do you solve them?
- Why is Immersion Silver Board Oxidized?
- Why is it Important to Wear Sulfur-free Gloves before Touching Immersion Silver Surfaces?
- What should you Pay Attention to when using Immersion Silver Boards?
- What are the Factors that Determine the Choice of a PCB Surface Finish?
- What is Immersion PCB Backing?
- What is the Thickness of the Immersion Silver Surface Finish?
- How does Immersion Silver compare to the ENIG Surface Finish?
What is Immersion Silver Finish?
This is a type of PCB coating that involves the use of a silver layer to protect the copper traces.
An electroless immersion reaction is undertaken to facilitate this process.
You can use this finish to prevent corrosion and maintain the integrity of your PCB before the soldering process.
Using this method guarantees an easy and safe assembly process.
It also offers you a superb flat surface to work on.
The common uses for this finish are aluminum wire bonding, EMI shielding as well as metallic dome contacts.
Silver is the most electrically conductive metal.
It thus offers good results for high-speed PCB applications when you use this finish.
Immersion silver PCB
How is Immersion Silver PCB Produced?
You can makea PCB with this finish by dipping it briefly into a solution that has silver ions.
The silver ions displace the copper metal in an electroless reaction to form a silver metal layer.
This yields a consistent flat surface for effective component assembly.
What is Immersion Silver Plating?
This is the process of covering a PCB’s copper surface by creating a thin silver layer over it.
You can achieve this by bathing your PCB in a solution that contains silver ions.
A consistent flat silver layer forms on the copper pads shielding them from corrosion and providing a good solderable surface.
This method became popular after the onset of RoHS and WEEE directives restricting the use of harmful plating substances.
It also ensures that your PCB lasts for a long time when you place it under storage.
What are the Advantages of Immersion Silver PCBs?
PCBs with this type of finish has an array of benefits when you use them.
Some of which are;
i. They have excellent surface planarity that makes it easy for you to work on. You can conveniently install surface components such as Ball Grid Array (BGA) and flip chips.
ii. They are RoHS compliant meaning that they are environmentally friendly and safe for your use.
iii. They have a good solderable surface allowing solder to spread nicely. This allows you to solder components efficiently.
iv. They have great resistance to environmental aging when you compare them to Organic Solderability Preservative (OSP).
v. This finish can withstand multiple reflows.
vi. Reworking is also possible with this finish.
vii. They offer a good alternative to ENIG finish.
viii. They are not susceptible to the Black pad effect.
ix. Their cost is also a middle range for the lead-free type of finishes.
x. They have better electrical property and you can use them in high-frequency devices.
What are the Disadvantages of Immersion Silver PCB?
There are several shortfalls that you may encounter with this type of finish.
Some of them are;
i. Silver coatings are likely to develop whiskers under electrical fields. This can short out components.
ii. They also require a special type of packaging to maintain their finish integrity.
iii. They are quite sensitive especially when handling. It is advisable to wear sulfur-free gloves when using them.
iv. They can also easily tarnish once you expose them to air.
v. During assembly, they have short operating windows between the stages.
vi. Peelable masks do not go well with this type of PCB finish.
What is Immersion Silver PCB Tarnish?
This is a condition that leads to the loss of the authentic color of the silver layer.
It commonly arises when you expose the PCB to air.
The silver material reacts with Sulphur and Chlorine which further forms Ag-S and Ag-Cl compounds respectively, on the surface.
This can also lead to the deterioration of the surface solderability performance.
To prevent this, you can apply an anti-tarnish agent after immersion silver.
Storing the PCB in an airtight and Sulphur free package can also secure it from tarnishing.
What is the Process involved in Immersion Silver PCB?
Coating your PCB with this method comprises of the following steps;
Immersion silver PCB
You first need to get rid of fingerprints, dust, and oxidation residues present on the board.
Make the surface wet to extract air that might be present in the plated through holes.
The purpose of this step is to modify the copper surface.
You can use sulfuric acid to create the composition of the liquid bath.
At this stage, you immerse the board into acid to prepare the copper surface for coating.
You should also do this to reduce the chances of oxidation.
iv. Immersion Silver
This step involves the reduction of copper metal by the silver ions in a solution to form a silver layer.
The process needs to be slow to ensure the formation of a uniform and consistent silver deposit layer.
This is the final stage where you apply a preservative antioxidant organic compound on the board.
Doing this prevents oxidation and displacement of the silver layer to ensure that it maintains its nature during storage.
How long can Immersion Silver PCB last before it is used?
This type of PCB has a shelf life of at least 12 months.
It is necessary to observe proper packaging and storage conditions to preserve the board’s integrity.
After keeping the PCB in storage for some time, it is wise to subject it to a solderability test.
How does Immersion Silver PCB compare to Immersion Gold PCB?
There are several comparisons between these two types of PCB finish.
Some of them are;
- Immersion silver provides higher electrical performance than immersion gold. This makes it a better and reliable choice to run high-frequency applications.
- Immersion silver is less costly when you compare it to immersion gold. This is because gold is a more expensive material than silver.
- Oxidation of the board is likely to occur quickly when you use immersion silver. This tarnishes the silver layer affecting its solderability. On the other hand, immersion gold is resistant to oxidation.
- Immersion gold offers a longer shelf life in comparison with immersion silver.
- Immersion gold also experiences a black pad, which is nonexistent when you use an immersion silver finish.
How can you Handle and Store Immersion Silver Finish Products?
These products are highly sensitive to handling and storage.
You need to adhere to the following precautions when using this type of PCB finish;
- You should wear gloves when handling the boards. This is because fingerprints may cause tarnishing of the surface and lead to solderability issues.
- You should store the board in dry conditions for a period ranging between 6 – 12 months.
- In case you store the PCB for a long time, it is wise to do a solderability test. This ascertains that its solder property is still intact before component assembly.
- You need to also avoid using surfactants or acid cleaners on boards that have this finish. Instead, you can use water washes that have a PH > 6.0.
- Sulfur free packaging materials are the best for storing PCBs with this finish. They prevent any chances for tarnish to occur.
- Once you open a package, you need to process the boards through the assembly as fast as possible. You should minimize its time in the open air.
- When baking the PCB to relieve stress or expel moisture, you should observe the right operating temperature and time.
What are the Specifications of the Immersion Silver PCB?
The specifications that are available for this type of finish method include;
IPC-4553A – It outlines the guidelines for using this surface plating on PCBs.
It also lays down the requirements for the silver layer thickness depending on the board’s performance criteria.
ISO 9001 – This specifies the standards for ensuring that products deliver on the customer and regulatory requirements.
What is involved in the Immersion Silver PCB Assembly?
There are several steps that you can undertake when assembling this type of PCB.
They comprise of the following;
· Solder Paste Application
In this step, you first select a suitable solder paste.
You then place a stencil over the board and apply the solder paste on the necessary parts.
This forms the part where you will position the PCB components.
· Component Placing
With the use of a machine, you then place the surface mount components on the solder paste paths.
· Reflow Soldering
After placing the components, you then need to solidify the paste.
You do this to adhere the components on the board.
You can use a reflow oven to generate heat that helps to facilitate this process.
· Inspection and Quality Control
You should inspect the board to ensure that no errors and misalignments exist.
Some inspection methods that you can use include manual checks, automatic optical inspection, and X-ray inspection.
· Through-hole Component Installation
In case your board requires plated through holes components, at this stage is when you insert them.
You can use either manual soldering or wave soldering depending on the complexity and requirement of your board.
· Final Inspection
At this stage, you test for the functionality of your PCB.
You can conduct a simulation to ascertain its performance.
In case the PCB fails the test, you can either recycle or scrap it depending on your company’s standards.
What is Immersion Silver PCB RoHS Finish?
This is a surface plating method that complies with the Restrictions of Hazardous Substances (RoHS) directive.
The guideline regulates the use of harmful compounds in electric and electronic devices.
Therefore, this finishing method is environmentally friendly as it does not utilize any of the dangerous substances such as Lead.
What is the Benefit of using Sterling in Immersion Silver Surface Finish?
Sterling grants you some advantages when you use it in the finishing process of your PCB.
Some of its benefits are;
- It produces a reliable and even silver layer that favors micro vias. This offers a solution to the emerging complex technological demands.
- It also yields strong and consistent solder joints.
- It has excellent wire bondability creating room for an excellent circuitry.
- It provides a wide range of versatility and flexibility for use on either horizontal or vertical equipment.
- It provides a better surface for complete flux and pastes compatibility. This yields a durable finish that can withstand extreme heat conditions.
What are the Common Problems when using an Immersion Silver Finish? And, how do you solve them?
Some of the issues you can encounter when using this finish and their solutions include the following;
Immersion silver printed circuit board
When you expose PCBs with this kind of coating to air, they quickly react with Sulphur and chlorine.
This causes a discoloration of the silver layer and the disruption of its solderability property.
To avoid this, you need to adhere to proper storage requirements.
You should store the board in an airtight and Sulphur free package.
Once you open the package to withdraw a board, reseal it quickly to preserve the remaining boards from contamination.
You can also use an anti-tarnish bath in the final step of the plating process to prevent this from occurring.
2) Silver Whiskers
This condition arises when you expose the PCB to environments with high hydrogen sulfide and humidity.
It may cause a short out of the board’s components.
You can use a conformal coating on top of the silver layer.
3) Galvanic Effect
This can occur between the cracks of the solder mask and copper surface during the immersion silver process.
The supply of silver ion to immersion silver experiences an impediment causing copper corrosion to form copper ions.
This effect affects surface solderability.
You should ensure a proper copper surface treatment during micro-etching to facilitate uniform immersion silver.
Why is Immersion Silver Board Oxidized?
There are several reasons as to why these boards undergo oxidation.
The main cause is due to its storage environment.
These boards can easily oxidize in high temperatures, high humidity, and high pollution surrounding.
The packaging solution you use and the storage time may also lead to oxidation.
Poor packaging that exposes the board to air can easily cause the board to oxidize.
Why is it Important to Wear Sulfur-free Gloves before Touching Immersion Silver Surfaces?
This is important because human hands produce sweat and can also have oil that easily pollutes the silver material.
This can lead to a reaction and deformation on the silver layer which causes discoloration and a thickness increase.
It, therefore, becomes difficult to solder components on this corrupt surface.
What should you Pay Attention to when using Immersion Silver Boards?
There are two things that you need to take note of when using this type of PCB.
- You should complete surface mounting and reflow within the first 24 hours once you open the vacuum package.
This prevents any chances for tarnish to occur.
- You also need to ensure that you adhere to the right baking conditions when using these boards.
What are the Factors that Determine the Choice of a PCB Surface Finish?
There are several factors that you need to consider when choosing the right finish for your board.
Some of them are;
- The cost of the process.
- The environment in which you intend to utilize the board.
- The product compliance to RoHS directive.
- The chances of high-frequency applications.
- The board’s shelf life.
- The shock and falls resistance ability.
- The operating temperature of your board.
- The quantity you need to produce.
What is Immersion PCB Backing?
This is a process that you can undertake to drive out moisture and relieve stress on your board.
You need to do this under a controlled environment that observes the right baking time and temperature.
You should also us an oven whose design is specific to conduct this kind of process.
What is the Thickness of the Immersion Silver Surface Finish?
This type of finish achieves an even thickness of 0.12 – 0.40um.
This aspect makes immersion silver 100 times thinner than traditional electroplated silver.
It offers a good flat surface that is also lead-free for easy component assembly.
How does Immersion Silver compare to the ENIG Surface Finish?
These two types of finish compare in the following ways;
PCB Surface finish
i. Immersion silver has a short and easy process cycle, yielding only one silver layer.
On the other hand, ENIG comprises of a complex process. You require an electroless nickel layer which you further cover by a gold layer to protect the copper.
ii. Immersion silver is a cheaper plating method when you compare it with ENIG. This is because of the extra material and process steps you would require for ENIG plating.
iii. You can easily perform rework on immersion silver PCBs unlike on ENIG which is quite difficult.
iv. Immersion silver is highly susceptible to tarnish when you expose it to air thus requiring strict handling. On the other hand, ENIG does not tarnish.
Now it’s your turn.
In case you have any question or inquiry about immersion silver PCB, Venture Electronics engineers are here to help – contact us now.