Difference between Flex and Rigid PCB Assembly
The SMT assembly of Flex PCB and Rigid PCB is basically the same but there are some unique aspects for Flex PCB boards.
1 ) Soldering Process
The surface of the Rigid PCB board is not flat, so we need to use some fixing devices or reinforcement for fixing.
2)SMT Component Placement
Flex PCB boards may need flexibility after assembly. An SMT fixture will be a good choice.
3)Reflow Soldering Process
The Flex PCB board must be dried before reflow soldering.
Design Considerations for Flex PCB Assembly
Important flex PCB assembly specifications that a designer needs to know.
1)Base materials: The most common base material used in flex boards is polyimide films. They need to have good heat resistance and electrical conductivity.
2)Number of layers: For dynamic applications, select a single layer board. For static, the number of layers can vary from 4 to 8.
3)Bend radius: Generally, the bend radius of these boards vary between 1 mm and 5 mm.
Applications of Flex PCB Assembly
Flex PCB Assembly is popularly being applied in many fields such as electronics, manufacturing, automotive, medical and miscellaneous etc.
●Electronics: calculators, baby toys, cameras etc
●Manufacturing: robotic Arms, processing machines, bar code equipment etc
●Automotive: air Bag Systems, antilock brakes, GPS Systems etc
●Medical: pacemakers, hearing Aids and heart Monitors etc
●Miscellaneous: resistors and satellites etc
Your Premier Flex PCB Assembly Supplier
If you are looking for a high-quality rigid-flex PCB and flex PCB assembly partner? You’ve come to the right place.
Venture is more than just a leading Flex(flexible) PCB Fabrication manufacturer but also a one-stop shop for all your flex PCB Assembly requirements, we provide high-quality flex PCB assembly services to engineers and companies all around the world, from component sourcing, flex PCB manufacturing, flex PCB assembly to testing, all under one roof.,
Flex PCBs, they are light, bendy and can be heat sensitive, so flex PCB assembly don’t play by the same rules as rigid applications in the assembly process.
To ensure the best quality and make sure the boards won’t get damaged while inside flex PCB assembly equipment, a flex circuit must have strong support by using a custom fixture pallet, the pallet also need to accommodate top and bottom configurations if the flex PCB is a double-sided flex circuit during flex PCB assembly.
Your Leading Flex PCB Assembly Supplier in China
Venture flex PCB assembly engineering team works closely with customers to optimize the array design and perimeter connections within the flex panels, at the design stage and also at the DFM review stage before production, we review your BOM and Gerber files. We have specifically developed proprietary techniques to improve and optimize the de-penalization process where special tooling is no longer required.
No matter you are an electrical engineer, a product designer, a system integrator or a maker looking for flex PCB assembly, Venture will be your perfect flexible electronic assembly house in China.
Through our 2 hours rapid response services from our 24/7 sales and tech support team, and excellent after-sales service, we will be your best flexible PCB manufacturing and assembly partner in China.
At Venture we can help you reduce vendor count, production delays, and improve overall circuit quality with Flex PCB assembly, pls feel free to contact us anytime for your flex PCB assembly projects.
Flex PCB Assembly: The Ultimate Guide
If you’re in the field of flexible electronics, then a knowledge on flex PCB assembly will help boost your business.
This guide covers everything you need to know about flexible PCB assembly – from advantages, BOM, component sourcing, PCB assembly techniques and many more.
By the end of this guide, you’ll be an expert in the flexible PCB assembly process.
Let’s dive right in.
- What is Flex PCB Assembly?
- Advantages of Flex PCB in Electronics
- How to Specify Bill of Material (BOM of Flexible PCB Assembly)
- Component Sourcing for Flex PCB Assembly Process
- Flex PCB Assembly Component Mounting Techniques
- Types of Flexible PCB Assembly Processes
- Flex PCB Assembly Specifications
- Quality Testing in Flexible PCB Assembly Process
- Flexible PCB Assembly Process
- Common Problems in Flex PCB Assembly
- Packaging and Shipping Flex PCBs after Assembly
- How to Get the Best Flexible Circuit Board Assembly Services?
What is Flex PCB Assembly?
Let’s start with the basics on flex PCB.
A PCB is an initial for the printed circuit board. It is a device that electronically connects and mechanically supports electrical components.
The connections depend on pads, conductive tracks, plus other features drawn on one or more layers of copper.
Flexible PCB Assembly
A flex printed circuit board is a type of technology where you will print the electronic circuits on flexible substrates.
You can identify the flex PCB with other names such as flex circuits, flexible circuit boards, flex boards or flexible electronics.
Flex PCB assembly is, therefore, the process of assembling all the components of the PCB to make a flexible PCB. The material you will use in making the flex PCB might vary from the material for rigid PCB.
Flexible PCB can take any form and can also go around bends.
Flexible substrates that you can use for printing the electronic circuits include peek, polyimide, or transparent polyester film.
Apart from that, you can find screen printed silver circuits on transparent polyester.
Advantages of Flex PCB in Electronics
Flexible PCBs offer a range of benefits in electronics. These include:
Part of flexible electronic
i.Packaging and Reduction of Weight
The design of the flex PCB increases flexibility and saves enough room to meet different density mounting designs.
Normally, the flexibility also enhances reliability and reduces the process of assembly. It is the solution to miniaturization and movement of electric products.
Flex printed circuits are light and thin, therefore, making the packaging quite simple and substantial.
It allows for the minimization of space with their ability to fold. It is possible to minimize space by applying the 3D geometry packaging.
Using the flex circuits can reduce the weight of the device in comparison to using wire harnesses and wires.
It replaces the wires and reduces the errors that are common in wired assemblies.
ii.Durability and Reliability
Flex circuits increases reliability of devices by eliminating different interface connections such as solder joints. The fewer the number of interconnections in a circuit the fewer the potential sources of failure.
Flex circuits low mass and ductility reduces the impact of shock and vibration therefore increasing the performance.
Also, the thermal stability of the material polyimide allows the flex circuits in high temperature applications. It reduces the possibility of thermal mismatch as compliant base films place less stress on the solder joints.
Apart from that the flex circuits are also resistant to UV exposure and radiation. It is an excellent circuit that offers perfect resistance to chemicals such as gasses, oils and acids.
iii. Cost Savings
Flexible polyimide films require smaller areas reducing the overall size of assembly and cost of material. In the assembly process, the assemblers require fewer parts for connectivity and reduces overall cost.
Simple assembly processes will reduce assembly errors and save on time. It will also save on the cost of doing regular tests on the device.
Assembly of flex circuits, therefore, eliminates the possibility of reject appliances thus saving on cost.
iv.High Temperature Applications
Polyimide is not only a flexible material but also a good conductor of heat. It allows for the exposure of the flex circuits to high temperature applications up to 400C.
Flex circuits do not expand and contract unnecessarily with the use of the polyimide materials.
v.High Density Applications
The properties of flex circuit materials allow it to perform better in high speed designs. The materials allow for better control of impedances.
Flex circuit assembly involves narrower lines and, therefore, gives way to higher population of high density devices.
A high population of denser devices on the flex circuit gives more space for more product features.
Flex circuits allow for radio frequency and electromagnetic interference shielding in different devices. It uses different types of materials such as copper layers, silver ink, and EMI shielding films.
vii.Components or connector assembly
Flex circuits accepts different connectors and components onto rigid PCB designs. It has integrated ZIF contacts providing simple modular interfaces to the environment of the system.
Other connections to rigid circuits include crimped contacts, direct solders, and ZIF connectors.
How to Specify Bill of Material (BOM of Flexible PCB Assembly)
What is the importance of learning about the bill of materials?
Well, there are quite a number of reasons that you will learn about in this section.
Without further ado, let’s begin with the definition of BOM as we proceed.
What is a bill of materials in flex PCB designs?
A BOM or bill of materials is simply a list of materials. In flex circuits, a bill of materials is simply a list of materials for the construction of flex circuits.
Apart from that, it is the link or communication tool between various departments. It links all the departments you will involve in the assembly of your flex circuit.
These include the procurement department, assembly department all the way to the functional testing department.
In short, you can describe the BOM as a list for the procurement of materials you will need for flex circuit assembly.
Other uses of the BOM include:
- It is the basis for the computer identification of different materials
- It forms the base for preparation of plans thus saving on time.
- It acts as the basis of creating support and picking.
- It allows you to have a track of the processing of flex circuits.
- The BOM makes the foundation of outsourcing and procurement.
- It is a quote reference you can use in calculating the cost of flex circuit assembly.
- It allows for the traceability of the materials you need for flex circuit assembly.
A good BOM often comes from the different flex circuit design software available. It implies, a part information you need for the BOM, is already on the software.
The software has a CAD library where it stores all the part information you need for the BOM.
As you integrate every part in your design, the information also comes with it from the library. Once you have all the design parts, you are sure of the availability of part information.
You will use the part information to generate a good bill of materials for your device.
Elements of a BOM
A BOM can have a lot of information on it but there are key elements that will make it complete.
The following is a list of the most common elements you have to include to complete a BOM.
· Comment section
Each part of the BOM has to have a comment section for describing the parts. The comment is usually a company part number that you can use to identify the part.
Apart from that, you can use other designations such as vendor part number for better identification.
As an example, you can use the company part number “27-0477-03” as a comment for easy identification.
It is typically the description of the parts you will list on the BOM.
Staying with the example of comment “27-0477-03”. The description can be “CAP 10uF 20% 6.3V”.
Each part on the flex circuit has to have a unique designator.
As an example, in case you are using a 10uF capacitor, the designator can be “C27”.
The foot print of a BOM is the name offered to the physical CAD footprint of the specific part.
Still on the example, C27 could use a CAD footprint identified as “CAP-1206”.
Typically, you will organize the BOM using the value you had on the comment section. The other core elements that you will need will be on the same line as that of the comment section.
Let’s use the examples above to make a clear description and a better understanding.
|27-0477-03||CAP 10uF 20% 6.3V||C19, C26, C27, C31, C46||CAP-1206|
The company that you will contract to make the flex circuit might have different element requirements on the BOM.
Additional information can include tolerance and values or different types of information you can relate to the part.
Your BOM can, therefore, be very long depending on the information you include.
Advance Uses of a BOM
The section above has been on the basics of the bill of materials.
There are different types of features of the BOM worth mentioning for better understanding.
Flex circuit BOMs, can have different elements part from the comments sections for better organization. You can, as well, use these elements to describe advancements in the design data.
Sample PCB components
Some of the examples include:
·Changing the format of the Bill of materials
You can organize the BOM differently to change how it looks. Usually, grouping of the BOM information begins with the comment section.
A reorganization of the BOM will allow you to use the footprints to group the information.
·Inclusion of different new elements
You have the freedom of including parts that are not stuffed in the Bill of Materials
·Generating BOMs for diverse components on the board
Creating different stuffing options for different variation parts, allows you to generate different BOMs.
The creation of different BOMs allows you to include different variants of the materials.
To conclude this section, it is important to note that the creation of BOMs changes with time. Better inventions, allow for inclusion of new element on the BOM.
Availability of BOM online, gives you the chance to update your BOM regularly as soon as you identify additional parts.
You can learn more about BOM here: What is BOM in PCB Design.
Component Sourcing for Flex PCB Assembly Process
Component sourcing is a process where you will search for the components for the flex circuit. It involves looking at different component suppliers that have the capacity of supplying the components you need.
Selection of a good supplier is multi-dimensional decision. You can search the internet for different suppliers capable of supplying you with the right components.
You should also be very careful with the information on the internet as some suppliers might not meet your demands.
It is critical to have a thorough review of the component suppliers since flex circuits are complex circuits.
Looking at the specialties and capabilities of different suppliers will give you an upper hand in components sourcing.
A better alternative is to allow your manufacturer to source the components. Many manufacturers know different credible and cheap components suppliers.
It will allow you to save on time as you will only need to provide the BOM and wait for the quotes.
Apart from that, you can decide to source the components personally. You can have a list of different suppliers that you know of their history.
Send the BOM to their respective offices and wait for their responses.
Component sourcing involves looking at the quality of the components you receive from different suppliers.
Checking the quality should go hand in hand with the cost of the components. You should be able to get the value of your money from the components you purchase.
Sourcing for components will also depend on the budget you are working with. Low budget will get you suppliers but you need to be careful with the quality of the components.
Manufacturers will advise you to get credible suppliers who will guarantee durability and functionality of the flex circuits.
Process of Getting a Quotation for Component Sourcing
The first step is preparing a good bill of material with all the components you require.
You can use the BOM template from your manufacturer and fill it up with all the component details.
After submitting the BOM, make sure that you make a request for the quotation for the products on the BOM.
PCB Component sourcing
It will take a day or two to get the quotation from the manufacturer. You can either approve of it or try different manufacturers and compare their quotations.
At this stage, you can now decide on the best quotation that will meet your needs. Allow the manufacturer to place an order of the components.
It usually takes around one week to receive the components at the manufacturers’ assembly factory.
Flex PCB Assembly Component Mounting Techniques
Why is it important to learn about the component mounting techniques?
Learning about the component mounting techniques will give you a deeper understanding of the assembly process.
In that case, let’s dive right in.
PCB component mounting
Component mounting techniques are the processes manufacturers use in placing the components of the flex circuit in place.
There are two main mounting techniques that manufacturers use in the assembly of flex circuits.
·Surface Mount Technology (SMT) for Flexible PCB
This process involves direct mounting of components on the flex circuit. This process is a replacement of the traditional through hole assembly process.
You can also identify it as SMD process as it involves surface mount devices.
Surface mount technology
You can use this process on integrated circuits and components of different sizes. As an example, you can use surface mount technology on mounting devices smaller than a pencil point.
·Through Hole Flex PCB Assembly
It involves connecting components through soldering of wire leads into through holes. The process requires the use of human hands.
It works best on components that have wires or leads for mounting through holes. The extra lead of the component sticks to the flex circuit by soldering. This process is suitable for mounting components of larger sizes.
Through hole mounting technology
Types of Flexible PCB Assembly Processes
After going through the mounting techniques, let’s have a look at the assembly processes available.
There are four fundamental types of assembling a flex circuit. These processes vary accordingly depending on the production conditions.
Flexible PCB assembly process
This section will take you through the most fundamental types of flexible circuit assembly.
·Single sided Flex PCB Assembly
Single sided flex circuit assembly is a process of assembling a flex circuit with one layer. It involves the use of a conductive or a metal polymer on flexible dielectric films.
The main features of the flex circuit are available on one side only. It involves the drilling or use of lasers to make holes on the base film.
Normally, the holes will act as component leads allowing them to pass during interconnection process. Here, the main process of interconnecting the component leads is soldering.
The fabrication process can include the use of cover coats or it may do without them. Nevertheless, using protective coatings above the circuits is a very common practice.
Single sided flex assembly
Surface mounting of devices on the sputtered conductive films enables the manufacture of LED films.
LED films are the main components in automotive lighting composites and LED glasses.
·Double sided Flex PCB Assembly
This is a types of flex circuit with two layers that can conduct electricity. The assembly process of the double sided flex circuits can either use plated through holes or not.
An assembly process without the through holes allows the association features on one side only.
Also, the military refer to this type of flex circuit as the “type 5” double sided flex circuit.
Double sided flex circuits allow the placement of components on both sides of the flex circuit.
It is not a very common practice but this type of device allows for placement of components on both sides.
Depending on the requirements of the design, the assembly of the double flex circuit uses protective covers.
The protective cover can either be on one side or both sides. The client can also prefer to avoid the inclusion of the protective cover.
It allows for easy preparation of intersect connections during the assembly process.
Most of the single sided flex circuits depend on the double sided substrate for construction. This because the double sided flex circuit substrates have one of the two intersect connections.
Double sided flex assembly
·Multi-layer Flex PCB Assembly
Multilayer flex circuits are types of circuits that have more than two layers of flexible circuits. The layers of the multi-layer flex circuits connect to one another via through holes.
Through holes do not necessarily define the multi-layer flex circuits as they can give access to the other layers.
The layers of the multi-flex circuits may or may not have laminations depending on the customer demands. In case of the inclusion of lamination, then the though holes are always an exemption.
Irregular lamination is very common in the areas that require extreme flexibility.
The process will involve leaving the foldable areas unbound with the laminate.
Multi-layer flex assembly
·Rigid-flex PCB Assembly
Rigid-flex PCB assembly is the process of making a type of hybrid flex. The rigid-flex circuit consists of both the flexible and rigid parts.
Moreover, the components stick to the board and flex substrate thus making a single structure.
The assembly process is the most common method for Military and commercial use. It is a specialty of low volume applications.
Remember, it is important to note that the rigid flex assembly is different from rigidized flex assembly process.
The layers of the rigid flex connect to one another electronically through different through holes on the layers.
Generally, the rigid-flex circuits have multilayer options. This option requires the use of two metal layers for assembly.
Rigid flex assembly
It is a common circuit that you can find in modern computers and laptops.
Flex PCB Assembly Specifications
As a customer, who needs to purchase a flex circuit, there are certain specifications you need to know.
These specifications will also help you in making a complete design that manufacturers understand.
This section will take you through some of the basic assembly specification you need to know.
Let’s dive right in.
1.Number of layers
Flex circuits are available according to different number of layers. The number of layers range from one to multiple numbers of layers.
Moreover, the number of layers on the flex circuit will depend on the customer specifications.
2.Board type – singe or in panel
The board type of flex circuits can either be single or panel board types. Depending on the specifications of the customer, manufacturers can make either of the two.
Panel board types allows for the mounting of more components in comparison to the single board type.
The dimensions of the flex circuits vary according to the device that the customer has in mind. Normally, the manufacturer will rely on the dimensions from the customer’s design.
There are however standard dimensions but in most cases it will depend on the type of device.
4.Quantity of flexible PCBs
Different devices require different number of flex circuits. So, depending on the type of device you intend to make, the quantity will vary.
A device that uses many flex circuits must be big. It might be a complicated device with multiple functions.
Flex circuits have different base materials depending on customer’s specifications. The base material in this case has to be flexible. The most common base material for flex circuit is the polyimide and polyester films.
Despite the high density of polyester films and polyimide they are also flexible and thin. Apart from that, the material has to have good tear and thermal resistance and excellent electrical conductivity.
The spacing between the conductors and the components vary accordingly. The minimum spacing will affect the bending radius of the flex circuits among other things,
For example, the minimum bending radius in a flex circuit can be between 1mm to 5mm.
Manufacturers will always depend o the minimum spacing from their customer’s specifications.
Here, size of the hole in the flex circuit will depend on the size of the component lead. The bigger the size of the component lead, the wider the size of the hole.
Indicate the hole size to the manufacturer so that he can know the size of the lead component.
Solder mask is not an obligatory addition to the assembly of flex circuits. In many cases the solder masks cover the solder points of the flex circuit components.
Flex circuits can do without solder masks depending on the method of mounting the components.
The silk screen acts as a cover on the base material. Having a silk screen on the flex circuit is an option.
A customer can either decide to have a flex circuit with a silk screen or not.
Also, silk screen is available in different colors that the customer can choose from.
Gold connectors are the main joints between the flex circuits and the boards. They are the connectors that join the flex circuits to the rigid boards.
Apart from being connectors they also transfer current from one end to another. It is a common feature on rigid-flex printed circuit boards.
There are two main types of gold fingers which include:
- Electroless Nickel Immersion Gold (ENIG)
- Electroplated hard gold hard and thick. suitable
Rigidized flex circuits depend on stiffener to make them stronger and more rigid. It ensures that there is no insertion force by making the circuits thicker.
Stiffeners allow for solder mounting by leaving localized areas. Manufacturers use it to protect the solders from damage.
Copper is the most common type of material manufacturers use in doing surface finishing. It has very good properties such as electrical conductivity that make it more suitable a material.
Note that, there are other types of surface finish materials. They vary according to functionality and customer’s preferences.
Quality Testing in Flexible PCB Assembly Process
The greatest joy of a manufacturer always comes when they successfully complete a customer’s design.
The design is never complete until the manufacturers test its functionality.
Flexible PCB assembly quality assessment
Let’s have a look at some of the testing processes for the flex circuits.
·Electrical testing of Flex PCB
There are two main types of flex PCB electrical testing methods. These include simultaneous flex circuit electrical test for mass production of flex circuits.
Quality tests with probes
The method many manufacturers use for testing other flex circuits include isolation or flying probe testing. Flying probe depends on a machine to fix and test the electrical circuit.
·Dimensional tolerance for Flex PCB
Dimensional tolerance test for flex circuits test the tolerance of the circuit according to its dimensions. Testing dimensional tolerance seeks to know if the dimensions of the flex circuit work well.
Manufacturers often design flex circuits of diverse dimensions. It is, therefore, important to test functionality before releasing to customers.
·Thermal testing for Flexible PCB
This test seeks to know if the flex circuit will withstand certain heat ranges. It involves using the flex circuits in different temperature ranges.
At the end of the test, manufacturers will be able to know the specific heat range of the flex circuit. With this information, a customer will know the conditions of operating the flex circuit.
·Ionic Concentration testing of Flexible PCB
Ionic concentration in a flexible circuit will determine the functionality of the product.
During the manufacturing process, ionic residues might be left on the device. These ionic concentrates might cause problems on the flex circuit in humid conditions.
Monitoring ionic concentration is an indication for the cleanliness of the flex circuit.
Flexible PCB Assembly Process
After going through the quality testing essentials, let’s have a look at the assembly process for flex circuits.
Flexible PCB assembly process
There are two main assembly processes for the flex circuits as you are about to learn in this chapter.
The assembly process of flexible circuits takes a completely different treatment method. In this case, the treatment method requires you to be very careful.
Remember, the flexible circuits are often delicate and any slight mistake might compromise the functionality of the circuit.
Most of the manufacturers would often have the design that you need first. As you submit the design, accompany it with all the design notes and requirements of the flex circuit.
These details allow the manufacturer to check on the functionality and manufacturability of the flex circuit.
So, the design will go through a DFM check for all design specifications for any problematic features.
It will help in reducing manufacturing costs as it eliminates the unforeseen errors. After adjusting all the issues, you are free to proceed with the assembly process.
i.Automated using PCB Assembly Machine
This process of assembling flex circuits depends on the use of machines.
First make sure that the machines are working and they are in perfect condition. Collect all the materials that you need including the components.
Automated PCB assembly machine
After that, you can configure the machine according to the specifications of the flexible circuit. The machine will automatically print the design on the flexible substrate. The flexible substrate can either polyimide or polyester films.
After that, the machines will also automatically punch through holes on the flexible substrate. If not, you can use the pick and place machine to mount the components on the substrate.
Depending on the specifications, you can apply surface finishing. It makes the flexible circuit have a unique outlook.
Some of the advantages of using the automated machine include:
- Low overall cost
- Reduction of human errors
- The development cycle of the product is short
- It ensures that the final product is of consistent quality
- Suitable for production of the flex circuits in bulk
ii. Manual Flex PCB Assembly
The assembly process begins with collecting all the necessary material you need to make the flex circuit.
Some of the materials you need include the substrate, copper, solder mask, silk screen among others.
Manual PCB assembly
Also, the materials you will use in this process should be flexible substrates, that can withstand very high temperatures.
You might need a machine to help draw the patterns on the flexible circuit. The machine can also help in making more accurate holes on the substrate.
After that, you can either use surface mount or through hole technology to mount the components. Once in place you can do a reflow soldering to solidify the adhering components.
Take the flexible circuit through an inspection process to ensure that it functions properly. The inspection process allows you to check on lose components on the flexible substrate.
Common Problems in Flex PCB Assembly
Note that there are problems that you may encounter during the process of flex circuit assembly.
It is normal to have such problems so you better do a test so that you can avoid coming across such problems.
Rigid flex PCB assembly
In this section, you will learn about the problems that you might encounter in the assembly process.
Without further ado, let’s dive right in.
·Need for individual scale for assembly
Flex circuits require individual attention to confirm that everything is in order. This process consumes a lot of time and tiresome. Some people might make mistakes in the process.
The time consuming factor makes the individual scale of assembly a big problem.
·Dealing with heat constrains
Normal operations of the flex circuit usually expose it to very high temperatures. Exposure to high temperature may last as long as you put the device to use.
Unfortunately, the high temperatures may burn the flex circuit substrate and the components. Every component on the flex circuit is able to withstand a certain range of heat.
The burn may also be as a result of poor spacing between the components.
·Poor Manufacturing of Components
Poor manufacture of components can also be a big problem. You will notice such problems through connection troubles, loose components, bad solder or residual flux.
Leaving the flux on the substrate after soldering can cause a lot of damage. Make sure you clean it properly.
Bad soldering can be as a result of cold soldering. It occurs when the technician does not apply enough heat for soldering.
Moisture can also be an issue in soldering as it will contaminate the solder.
It will result in connection issues and the potential of burning the components.
Exposing the flex circuit to a series of environmental factors may cause problems on the circuit. Environmental factors include dust, cold and heat.
As temperature rises, the environmental factors can also expand and destroy the solder joints. Such issues will cause problems and disable the functionality of the flex circuit.
Unfortunately, components may be too old for proper functionality of the flex circuit. This factor is often beyond your control.
Older components lose their quality and in the short run, they will break down. You can actually replace the old parts instead of making a new flex circuit.
The possibility of creating voids through deposition may result into problems. These voids are holes or gaps in plating that may hinder the flow of electric current.
Uneven deposition process may lead to contamination, and air bubbles among other issues.
·Insufficient Copper-to-edge Clearance
Copper is a very important component in the assembly of the flex circuit. As important as it may be, it might also lead to problems due to corrosion.
Cover the copper with other materials to prevent it from corrosion. Lack of proper clearance between the edge and the copper may expose the copper after trimming.
Exposure of copper might lead to corrosion thus causing more problems.
·Missing Solder Mask Between Pads
Lack of enough solder mask between the component pads may lead to formation of solder bridges.
Solder bridges will expose the copper to environmental factors. This will in turn lead to problems on the flex circuit.
Acid traps or acute angles originate from trapping of acids through ammonia based etching. The acid will stay longer in the trap and eat away part of the flex circuit.
It will lead to compromise on the connections and defects of the circuit.
A void between the thermals and component pads may lead to an incomplete connection. It results to less transfer of heat thus overheating the flex circuit.
In the long run, it might the whole circuit rendering it useless.
Electromagnetic Interference (EMI) and Electromagnetic Compatibility (EMC) are common issues in flex circuits.
EMC usually propagates, generates and invites electromagnetic energy. EMI is the damage resulting from EMC.
Too much EMI will create a defective flexible circuit. Electromagnetic issues originate from flaws in the design.
The assembly process of flex circuits involves the use of certain chemicals. In many cases, the manufacturers clean the chemicals away after completing the work.
At, times chemical residues might remain on the flexible circuit leading to corrosion of the device.
·Not Using DFM
Design for manufacturability (DFM) is a process of eliminating errors on the design before assembling the circuit. Skipping this process may lead to more problems on the flex circuit after assembling the device.
Stacking copper traces on top of each other may lead to cracks on other copper traces above the bending radius. Cracks on the copper traces will affect the circuit and the flow of current.
·Stress Points in Conductors
Manufacturers often encounter problems of creating stress joints on the flexible circuits.
Trace arrangements may not work properly with the bending or flexing of the flexible circuits. Users encounter cracks and broken circuits when they try to bend the circuits.
·Solder Joints Too Close to Bend Point
The solder joints are often quite rigid in comparison to the rest of the flex circuit. In case the solder joint is too close to the bending joints, then it might crack.
Cracking will expose it to other factors making the circuit to fail.
·Solder mask/Coverlay Opening Not Wide Enough
It is important to make the spacing between the solder masks or coverlay wide enough.
Small spaces might compromise functionality of the device especially when going through other processes.
Packaging and Shipping Flex PCBs after Assembly
We might be out of the woods with the completion of the assembly process.
Well, if you think so, then you are wrong.
One sector of packaging and delivering flex circuits never receives so much attention. Many manufacturers realize that packaging is important when they experience damages during transportation.
Let’s have a look at the packaging process in preparation for shipping.
The main function of packaging well before shipping is to ensure that the package reaches the customer in good condition.
Here are some of the factors to consider when packaging flex circuits.
Correct transport of the flex circuit will occur if the package has clear labels. The label might consist of part number and the quantity in the package. Remember to indicate the customer’s location to avoid confusion.
Lack of proper labeling might result in delays of the product at the destination dock. The supplier might also pay too much in case it gets a black mark.
Many customers often request for proper packaging against corrosion interferences. The packaging can have a moisture proof bag and a desiccant to reduce moisture build-up.
Also, the desiccant consists of silica which absorbs all the moisture making the package dry.
Manufacturers can use moisture proof ESD bags to protect the flexible circuits from ESD damage.
The package can either be conductive or metalized to reduce ion build up. This will reduce static discharge whenever the customer opens the package.
To avoid mechanical damage, pack the flex circuits in proper size poly bags. You can also use packaging trays with special molds.
These trays will hold the flex circuits in place while on transit or storage.
Remember that these packages will attract additional transit fees.
You can choose to customize the packages to avoid additional fees on the packages.
All the above considerations will ensure that the package arrives safely.
How to Get the Best Flexible Circuit Board Assembly Services?
The information you have on flex circuits must be nagging you.
You might be asking about the best way of getting the best flexible circuit assembly services.
Worry no more as you are about to answer your questions.
The process of getting the best flexible circuit assembly services involves looking at the following factors.
- Confirm the reliability of the supplier. You can ask around or look for more information online.
- Look at the capability of the supplier. In this case, check out the products the supplier has. Check the quality and the quantity they are able to produce.
- Remember that time is also a factor to consider. A good manufacturer should have the capability of assembling the circuit in good time.
- The cost of assembling the flex circuit will vary from one manufacturer to the next. Identify a manufacturer who will offer the best quality at a reasonable price.
- Consider the experience that the manufacturer has in assembling the flex circuits. Go as far as inspecting the certifications the company has.
- Explore the testing options that the company uses in making sure the circuits function properly.
- Ask about the support that they offer to their customers. How often are they available for consultations?
- You have to take the red flags very seriously. They act as warning signs that will tell you to avoid certain companies.
You can rely on the information you receive from people. Look at their recommendations and do a background check on the manufacturer.
Also, you can, as well, visit the assembly grounds and have a look at their products.
In the long run, you will have many samples that you can choose from.
Factors that will indicate the company you are working with is legitimate include:
- Project discussion
- Provision of resources and getting started on the project
- Staying in touch through the assembly process
- Receiving your product in good condition.
- Check in and customer support.
With this information at your fingertips, you are now an expert.
You are capable of finding a good manufacturer who will assist you in making a good flexible circuit.
You are also in a better position of negotiating terms for a proper deal.
What are you waiting for?
Pick up your phone and contact your supplier and negotiate a good deal.