Why is thin PCB so popular?
●Constrained by space or margin, or the need for design purposes, people need thinner thicknesses such as 0.25 mm, 0.20 mm or even 0.15 mm so that PCBs can be used for SIM cards, sensor cards.
●As the market demand for thinner devices drives attempts to make designs more portable, lighter, and more flexible, the use of thin PCBs is becoming more widespread.
●Thin FR4 PCBs can be made as thin as flexible PCBs and can be bent like flexible circuits, but are stronger and less expensive than the same copper traces on each board.
What is the thin PCB stackup ?
Due to the thickness, the board stackup of thin PCBs is simpler than other printed circuit boards, and although its structure is almost identical to that of ordinary FR4 PCBs, the core material and prepreg are thinner and can be used for production.
Venture designs and manufactures thin PCBs with more careful and precise control of each manufacturing process, and for some processes different manufacturing equipment is used, so as to ensure a smooth process in handling of thin boards.
Why LF HASL is not recommended for Thin PCB ?
Lead-free tin is also a common surface finished for PCBs. Why is LF HASL not recommended?
That is because in the LF HASL process, PCBs are easily blown away and one would use heated compressed air to level (blow) the coating melted tin (lead) solder, and in the process, the traces are easily broken as well.
So usually, we do not recommend LF HASL finishing for Thin FR4 PCBs.So It will be better to use OSP、ENIG and ENEPIG.
Ultra-Thin PCB FAQ
●Is it possible to make BGA on Ultra-thin PCB?
—Yes, the min through-hole requirement is 0. 2mm. if the vias in the pad without filled something, then we can make a min vias is 0. 15mm.
●What is the minimum line width and line spacing for ultra-thin pcb?
— The smallest routing width and space Venture can make for ultra-thin PCB is 4mil / 4mil.
●What is the common thickness of Ultra-thin PCB?
—Ultra-thin PCB’s common thickness is 0. 1mm – 0. 6mm. The common copper thickness we can provide is 0. 5oz , 1oz, 2oz. 3oz .
How to control the holes tolerance of ultra-thin PCB ?
●Control the stacking layers before drilling ,for board thickness is 0.15mm PCB ,the stackup can not more than 12 layers .
●At the PCB top side，we will use Al material to protect the raw materials to dissipate heat during drilling, and fix the board by put the board at the bottom side.
●We will control the number of times the drill is used and maintain the drill regularly, eliminating each drill after 1,000 cycles.
●Control the position tolerance of vias ≤ + / – 3 mils.
What is the difference between Ultra-thin PCB and FPC PCB ?
●Material Difference:FPC use PI(polyimid),Ultra-thin PCB use FR4 .and FPC is more flexible ,but ultra-thin PCB is cheaper than FPC .
●Surface finished:There are some limit when choose Ultra-thin PCB,with different
material characterisetics and produce ways,there are have difference produce process Venture can support surface fnished ENIG for board thickness is 0.10mm .
●Flxture of Producetion :It need special equipment for Ultra-thin PCB ,such as specialized cutting machine,Thin plate rack.Horizontal transporters and so on .
This extra thin printed circuit means the thickness of the printed circuit board is thinner than normal PCB. For most of FR4 PCB, minimum thickness is 0.3mm or 0.4mm, whatever it is 1L or 2L. For 4L, it will be more about 0.6mm.
Venture also provides LED ultra-thin PCB.
Your Leading Thin PCB Supplier in China
Are you looking for an excellent quality thin PCB? Choose from the leading manufacturer of thin PCBs, Venture. Here at Venture, we guarantee you the quality ultra PCB. We can manufacture different types of PCBs according to your specifications.
There are several types of PCBs depending on the application, among them are flexible PCB, rigid-flex PCB, HDI Flexible PCB, and etc.
During the design phase, flexible printed circuit boards (PCBs) aren’t much different than rigid boards, except that the designer must account for the mechanical complexity associated with flex circuits. For instance, a flexible PCB can tear if flexed beyond its capability during installation. So, before taking up the electrical design, it is very important to create a mechanical model of the PCB and test it for a proper fit.
Venture has been making them more compact and lighter primarily by decreasing the size of the copper features and board materials. To make it possible, we use extremely thin base materials to take miniaturization beyond what was previously possible without compromising reliability or performance.
A great deal of miniaturization can be achieved in the X and Y directions. Miniaturization in X / Y direction can greatly reduce the footprint of PCBs, while miniaturization in the Z direction reduces the overall thickness of the device and leaves more space for other components.
The level of compactness is possible by using rigid and flexible ultra-thin base materials to make highly reliable PCBs that are thinner.
Using thinner flex materials rather than traditional thick flex materials can reduce the space needed for the PCB even more.
Ultra-thin rigid materials are available for applications that require a 2D PCB. These are typically used as packaging substrates for ICs, where they help make the entire component very thin.
This extra thin printed circuit means the thickness of the printed circuit board is thinner than normal PCB. For most of FR4 PCB, minimum thickness is 0.3mm or 0.4mm, whatever it is 1L or 2L. For 4L, it will be more about 0.6mm.
The reliability of the interconnect structure improves with thinner stack-ups when using ultra-thin materials. Smaller expansion along the Z-axis results in less stress for vias during temperature cycles.
Therefore, we can conclude that ultra-thin PCB base materials are suitable for all markets where miniaturization and high reliability play a role. They can enable miniaturization with increased functionality through higher-density designs.
Thinner material leads to smaller vias, reduced aspect ratio of vias, less copper plating, smaller lines and spaces, and better fill grades, but it can also increase handling complexity.
In China, Venture is the leading manufacturer of thin PCBs, we have more than 20 years of experience and our aim is to provide the best quality thin PCBs.
We accept small or large quantities for every Thin PCB order.
For more information, please contact us.
Thin PCB: The Ultimate FAQs Guide
I know you’re probably looking for thin PCB.
Or, you would like to learn more about thin PCB.
That’s why this guide will answer all questions you have been asking about thin PCBs – from benefits, uses, quality standards to drilling capability, just to mention a few.
- What is Thin PCB?
- What are the Advantages of Thin PCB?
- Which are the types of Thin PCB?
- What are the factors to Consider When Determining the Thickness of Thin PCB?
- Is there Minimum Thickness for Thin PCB?
- What are the Applications of Thin PCB?
- What is the Minimum Drill Size for Thin PCB?
- Do the Drill numbers Affect the Cost of Thin PCB Fabrication?
- What is the Meaning of the Aspect ratio in Thin PCB?
- What are the Key Factors to Consider When Selecting Thin PCB Material?
- Are RoHS Compliant Thin PCB also Halogen-free?
- What is the Significance of UL Marking on Thin PCB?
- How is Back-Drilling Technology important in Thin PCB?
- What Does T260, T288, and T300 Represent in Thin PCB?
- Are there Quality Standards for Thin PCB?
- What are the Best Substrate Material for Thin PCBs?
- Which are the Available Surface Finishes for Thin PCB?
What is Thin PCB?
This is a type of printed circuit board that is thinner than ordinary PCB but thicker than Ultra-thin PCB.
The thickness of a thin PCB is often 0.5mm, while that of the standard circuit board is o.6mm and above.
Thin PCB substrates facilitate exceptional connection densities, high thermal conductivity and offer maximum reliability.
Moreover, this PCB type ensures high-accuracy geometries of insulator and conductor materials.
What are the Advantages of Thin PCB?
Here are the main benefits of using Thin PCB:
Minimized Weight and Space
The design of thin PCBs makes them have lightweight and save on space.
This improves their flexibility to satisfy a thinner and higher density PCB mounting design.
Increase Reliability and Repeatability
Because of reduced internal hardware connections, this PCB type guarantee performance reliability, and repeatability of fabrication.
Due to their excellent thermal properties, the cooling of components of thin PCB is much easier.
Moreover, the high glass transition temperature of the board ensure efficient functioning of components in high-temperature applications.
· Improved Aesthetics
The PCBs have light, thin, and compact structures made using polymer substrate having etched copper circuitry.
They range from single-layer to multilayer thin printed circuit boards.
· Eliminate Connectors
Thin PCB features reduced internal connections, like the bottom line, common solder point, and trunk line.
This reduces the volume of the board by about 70 percent of the standard PCB.
· Excellent Electrical Performance
This type of PCB offer consistent electrical performance for high-speed PCB applications.
Their low dielectric constant enables stable signal transmission.
Which are the types of Thin PCB?
Here are the common types of Thin PCB available in the market:
· Thin PCB
This type of thin PCB cannot be folded or twisted like flexible thin PCBs.
It is composed of copper paths and traces that are integrated on a single or multiple layer circuit board.
The base material is fabricated using a rigid substrate that provides the strength and rigidity to the circuit board.
After the manufacturing of rigid thin PCB, they cannot be folded or modified.
The cost of the PCB type is relatively lower compared to flexible thin circuit boards.
This makes them the commonly used types of thin PCB.
· Flexible Thin PCB
Also referred to as Thin Flex PCB, this type of printed circuit board is fabricated using flexible laminates.
They are highly reliable boards made of polyester or polyimide substrate materials.
The main features of flexible thin PCB include lightweight, high wiring density, good bending characteristics, and thin thickness.
The processes and technologies applied in flex thin PCB substrates are similar to those in rigid thin PCB laminates.
Nevertheless, flexible thin laminates mainly use organic materials that are either transformed to substrates from liquid phase or readily available as film material.
With this type of PCB, several forms of liquid crystalline polymer or polyimide are mainly utilized as substrate material.
Typically, the thickness of flexible thin PCB ranges from a few micrometers to hundreds of micrometers.
What are the factors to Consider When Determining the Thickness of Thin PCB?
Here are some of the considerations when deciding the thickness of thin PCB:
Thin printed circuit board
- Weight – This is an important factor since thinner finishes lead to a lighter circuit board.
- Flexibility – The extent to which the thin PCB should be flexible will dictate how thick it needs to be.
However, flexible thin circuit boards are susceptible to breaking, yet too thick types can be relatively heavy.
- Space – You need to consider the amount of space you will work with. Thin PCBs use less space, and smaller devices will need smaller circuit boards.
- Connections – The connector types you require on the thin PCB will determine the thickness level required.
- Component Compatibility – Some components of thin printed circuit board need a specific level of thickness.
- Impedance Matching – The PCB thickness corresponds to the dielectric material thickness. The dielectric is the PCB component that aids with impedance control. Therefore, when the impedance is vital, the board thickness is equally vital.
Is there Minimum Thickness for Thin PCB?
Thickness of PCB
Typically, thin PCB has a minimum thickness of 0.2mm, with just a single core layer and at most two copper layers.
More layers of copper are only practical by interchanging more prepreg and core layers.
To manufacture mechanically sound thin PCBs, you need to uniformly distribute the layers.
This is done by ensuring an odd count of dielectric layers and even a count of copper layers.
Therefore, PCB applications requiring high layers number can minimize their general thickness by utilizing these thin core choices.
However, selecting an extremely thin PCB might limit the options of applicable surface finishes.
Every surface finish features a unique fabrication process depending on the production technique and material properties.
What are the Applications of Thin PCB?
The common applications of thin PCB include using them in:
- Sensor cards
- SIM cards
- Wearable devices
- Memory cards
- Digital camera
PCB surface finish types
· Electroless Nickel Immersion Gold
ENIG is the most common choice and is applied on approximately 80 percent of circuit boards.
The finish gives a narrow, gold, solderable coating that screens the copper traces using a nickel boundary between the copper and it.
ENIG is a suitable lead-free alternative that forms a long-lasting finish.
· Hot Air Solder Leveling
With HASL, clamps hold the board vertically and dips immerse it in a flux bath and eventually into a melted solder hot vat.
Hot air knives are used to level off the finish, consisting of tin or lead then it is lifted from the molten solder vat.
This makes sure there is an even thickness over the whole thin PCB.
HASL was some time back the most common finish though presently it is only applied in aerospace and military PCB applications.
· Lead-Free HASL
The features and applications of this type of PCB surface finish are similar to HASL.
However, it virtually lacks no lead material.
Rather, the alloy comprises copper and tin, nickel and tin, ore, copper, tin, germanium, and nickel.
This is the most common type of surface finish used in PCBs currently.
· Immersion Tin
In this surface finish for PCB, a chemical procedure is utilized to deposit a thin layer onto the surface of copper.
It is usually employed in high-speed thin PCBs and performs well to shield the copper from oxidation.
However, copper and tin being that close can result in diffusion from one material to the other, leading to issues.
· Organic Solderability Preservative/Entek
With this type of thin PCB surface finish, a thin material layer is spread over the copper to screen it before soldering.
However, this water-based organic finish is not popularly used nowadays.
· Hard Gold
In this finish, you plate hard gold over the nickel that adheres perfectly and doesn’t degrade easily in comparison to other finishes.
Due to its longevity, this type of thin PCB surface finish is utilized in circuit board applications involving mechanical contact.
· Immersion Silver
Same as in, immersion silver finish is applied in high-frequency thin PCBs and do not constitute any nickel.
Nevertheless, this surface finish does need special storage since it tarnishes when subjected to air.
What is the Minimum Drill Size for Thin PCB?
The minimum drill size refers to the smallest required vias diameter to be made on a thin PCB.
Technical limitations during the process of manufacturing, such as plating and drilling methods, restrict the minimum size of thru-holes.
Some PCB manufacturers can drill minimum hole diameter of 0.15 mm for ordinary vias and 0.1 mm through laser drilling.
However, the leads of the thru-hole usually exceed the minimum drill size.
Therefore, you should only consider the minimum drill size when determining the size of the vias.
It is particularly important when you have a high-density design that needs the smallest practical via holes.
Actually, PCB producers have limits of how minute the drill can be on the thin PCB.
The diameter size can be represented by the aspect ratio entailing starting and finished aspect ratio.
The starting aspect ratio refers to the size of the hole actually drilled, whereas the finished refers to the size of hole after regular plating.
A designer works with the finished aspect ratio while the manufacturer refers to the starting one.
Due to these differences, it is important to clarify the value being referenced to during the designing of thin PCB.
Moreover, the aspect ratio cannot be below the finished minimum drill size. This is because it depends on the minimum drill.
Do the Drill numbers Affect the Cost of Thin PCB Fabrication?
No, most PCB manufacturers do not charge based on the number of holes.
Mostly only charge for special specifications like controlled depth drilling, blind holes, castellated holes, among others.
However, there are several other considerations when factoring drill holes, which can influence the lead time.
The factors include the actual hole size and number of different sizes of holes.
Drill holes count affects the lead time due to the amount of effort and time required to finish the fabrication of the thin PCB.
Typically, for smaller orders or prototyping, the count of drills will not have an effect on the PCB manufacturing lead time.
Nonetheless, this might not be the case with larger production orders.
Moreover, the number of differing drill holes size can significantly affect the lead time of thin PCB fabrication.
With several different sizes of drill holes, re-tooling of the drilling equipment will be necessary, which increases lead time.
Typically, the time spent on changing tool would be used to drill about 200 holes.
Therefore, it is advisable to limit the number of unique sizes of hole where possible.
Choosing a medium between two required hole sizes can aid in reducing the production time.
Moreover, the fabrication of thin PCBs that need laser drilling can as well be more expensive.
What is the Meaning of the Aspect ratio in Thin PCB?
The aspect ratio of a thin PCB microtia is the ratio of hole depth to the diameter of the via.
For example, the aspect ratio of an ordinary PCB with 0.062 inches thickness and 0.020-inch through-hole, will be 3 to 1.
It is applied as a guide to ensure that the PCB manufacturer does not surpass its equipment potential during holes drilling.
Typically, the aspect ratio must not exceed 10:1 for standard PCB vias.
This would enable a PCB with 0.062-inch thickness to have a via of 0.006 inches drilled in it.
However, the ratio is quite different with microvia because of its depth and size.
Plating tiny holes can be a challenging task.
Attempting to plate a microvia passing across 10 layers of thin PCB can lead to a lot of issues for the fabricator.
However, the plating gets much easier when the via passes through just 2 of those layers.
IPC initially described microvia depending on its size which was equivalent to or less than 0.15 mm.
The size got common with time prompting IPC to change the definition to prevent constant updating of its specifications due to advancing technology.
The current IPC definition of a microvia is a hole with an aspect ratio of 1:1.
Furthermore, it specifies that the hole should not surpass a depth of 0.25 mm or 0.010 inches.
What are the Key Factors to Consider When Selecting Thin PCB Material?
Here are the main factors that you should consider when choosing PCB material:
· Coefficient of Thermal Expansion
This is a measure of the extent to which the PCB material expands on heating.
This is particularly important in the Z-direction.
With unsuitable CTE, you can experience failures during assembly when the PCB material expands faster above Tg.
Lower CTE is the best choice, and materials can feature similar Tg but different CTEs.
On the other hand, certain materials can feature higher Tg and also possess a higher CTE.
· Glass Transition Temperature (Tg)
This refers to the temperature at which the PCB material transitions from a fairly rigid glass-like laminate to a more flexible plastic-like material.
It is an important factor since the properties of the thin PCB will change with temperatures above Tg.
· Decomposition Temperature (Td)
Td is the temperature at which the PCB material starts to degrade.
The analysis technique applied establishes when 5 percent of the laminate weight is lost.
It is the point at which the material reliability is jeopardized and delamination may happen.
Therefore, higher reliability thin PCB requires a Td ≥ 340 degree Celsius.
· Time to Delamination
This is the technique that measures the time when the PCB thickness is irreversibly altered at a predetermined temperature.
It is the duration at which the material expands to an extent it delaminates.
Are RoHS Compliant Thin PCB also Halogen-free?
No, that is not always the case.
The RoHS directive bans 2 bromide flame retardants, polybrominated diphenyl ethers (PBDE) and polybrominated biphenyls (PBB).
Most types of PCBs always use a bromide flame retardant referred to as Tetrabromobisphenol A (TBBP-A).
What is the Significance of UL Marking on Thin PCB?
If your thin PCB gets a UL label from the manufacturer, it implies that the board satisfies all established flammability and safety requirements.
Particularly, a UL mark implies that:
- The base material applied satisfies a stipulated flammability level as specified in UL94.
For instance, if the material is exposed to a naked flame and then withdrawn it extinguishes by itself within 10 seconds.
Moreover, it does not sprinkle any burning particles.
- The base material for the thin PCB fulfills the stipulated level of capacity to resist flaming from external sources of electricity.
- PCB Manufacturer has used a base material that satisfies the needed electrical breakdown value.
This refers to the voltage difference under which the base material insulation features may begin to degrade and cause safety problems.
- The base material employed in the thin PCB complies with the levels of performance for direct maintenance of current carrying potentials. This is as stipulated in UL 796A.
How is Back-Drilling Technology important in Thin PCB?
For high-frequency thin PCB applications, it is essential to avoid signal loss.
Typically, signal passes via a thru-hole that links the various PCB layers.
Some via section parts are considered ‘excess’ when the signal is to travel from first layer to second layer, say in 6 layer PCB.
Therefore, it is necessary to remove the extra copper from the via since it functions as an antenna and affects the signal.
Back-drilling is applied to eliminate the excess copper within the via to achieve better signal stability.
The technique applies controlled depth within Z-direction. Ideally, a shorter stub (extra copper) leads to better outcomes.
Typically, the size of back-drilling needs to be 0.2 mm greater than the equivalent via.
What Does T260, T288, and T300 Represent in Thin PCB?
T260, T288, and T300 denote the duration that a thin PCB will endure a specific temperature before it starts to blister or delaminate.
The temperatures are 260, 288, and 300 degrees Celsius respectively.
The tests are carried out in a Thermo-Mechanical Analyzer (TMA).
The figures are considered as short term indicators of a PCB resistance to solder processing.
For that matter, they are taken as the minimum requirements for Lead-Free thin PCB as stipulated by IPC.
Are there Quality Standards for Thin PCB?
Here are the main safety and quality standards that your chosen PCB manufacturer should meet:
- IPC Standards
- UL Standards
- REACH Standards
- ISO Standards
- EN Standards
- RoHS Standards
- British Standards
- FCC Standards
- IEC Standards
What are the Best Substrate Material for Thin PCBs?
The common substrate materials for thin PCB consist of:
- Polyimide material
- Polyester material
- Polymer material such as PTFE, PEN and Aramid.
The substrate needs to be selected depending on their cost and performance. Polyimide is the common substrate material used in thin PCB.
It is a type of thermosetting resin that has a high melting temperature.
Moreover, it is different from other thermosetting resin since it can still retain elasticity after thermal polymerization.
Polyimide features outstanding electrical properties and high thermal resistance.
Nevertheless, the material has poor tear strength and results in high moisture absorption.
Furthermore, adhesives also have an instrumental purpose of bonding substrate material and copper foil.
The common adhesives used in thin PCB include PET resin, polyimide resin, acrylic resin and modified epoxy resin.
Acrylic resin and modified epoxy resin are the popular ones due to their great adhesive force.
Venture Electronics offers unlimited capabilities in the PCB fabrication industry.
Whether you need ultra-thin PCB, thin PCB, or standard sizes of PCBs, Venture Electronics offers a perfect solution.
Contact us today for all your thin PCB needs.
Which are the Available Surface Finishes for Thin PCB?
There are 7 main types of surface finishes for PCB consisting of: