The biggest difference between fpc assembly manufacturer and common fpc manufacturer is: fpc assembly manufacturer including SMT components assembly.
As many customers have confused about it ,what’s the difference towards to the fpc assembly manufacturer and fpc manufacturer. Today we will explain the details as below contents.
By comparing the difference between the two process flows, you will know why the fpc assembly manufacturer has an advantage.
Firstly,let’s talk about basic normal fpc manufacturer.The fpc manufacturer mostly deal with the fpc production process.
Process flow of common fpc manufacturers
1. FPC board cutting
Except for some materials, the materials used for flexible printed boards are basically rolls. Since not all processes must be processed by tape-reel technology, some processes must be cut into sheets to be processed, such as the drilling of metalized holes of double-sided flexible printed boards, which can only be drilled in sheet form at present. So the first process of double-sided flexible printed board is cutting.
Whether it is single-sided, double-sided copper foil laminate or cover film, the accuracy of the opening size can reach ±0.33.
2.1 CNC drilling FPC board holes
Most of the holes in the double-sided flexible printed board are still drilled with a CNC drilling machine. The CNC drilling machine and the CNC drilling machine used in the rigid printed board are basically the same, but the drilling conditions are different. Because the flexible printed circuit board is very thin, it is possible to overlap multiple pieces of drilling. If the drilling conditions are good, 10 to 15 pieces can be overlapped for drilling.
The backing board and cover board can use paper-based phenolic laminate or glass fiber cloth epoxy laminate or aluminum plates with a thickness of 0.2 to 0.4 mm. Drills for flexible printed boards are available on the market, and drills for drilling rigid printed boards and milling cutters for milling shapes can also be used for flexible printed boards.
2.2 Punching FPC board holes
Punching small apertures is not a new technology, and has been used as mass production. Since the reeling process is continuous production, there are many examples of using punching to process the through-holes of the reel.
But batch punching technology is limited to punching diameter O. Compared with the drilling of the CNC drilling machine, the 6~0.8mm hole has a longer processing cycle and requires manual operation. Because the size of the initial process is large, the punching mold is correspondingly large, so the mold price is very expensive.
Although mass production is beneficial to reducing costs, the burden of equipment depreciation is large, and small batch production and flexibility cannot compete with CNC drilling, so it is still not popular.
2.3 Laser drilling FPC board holes
The smallest through holes can be drilled with a laser. The laser drilling machines used to drill through holes on flexible printed boards include excimer laser drills, impact carbon dioxide laser drills, YAG (yttrium aluminum garnet) laser drills, and argon gas. Laser drilling machine, etc.
3. FPC board hole metallization
Due to its softness, flexible printed boards need special fixing fixtures. The fixtures can not only fix the flexible printed boards but also must be stable in the plating solution. Otherwise, the thickness of the copper plating will be uneven, which will also cause disconnection during the etching process.
And the important reason for bridging. In order to obtain a uniform copper plating layer, the flexible printed board must be tightened in the fixture, and work must be done on the position and shape of the electrode.
4. The cleaning of the surface of the FPC board copper foil
In order to improve the adhesion of the resist mask, the surface of the copper foil must be cleaned before coating the resist mask. Even such a simple process requires special attention for flexible printed boards.
5. FPC board coating of resist
Now, the resist coating method is divided into the following three methods according to the precision and output of the circuit pattern: the screen printing method, the dry film/sensitization method, and the liquid resist sensitization method.
6. The formation of FPC board conductive patterns
The photosensitive method is to use an ultraviolet exposure machine to form a circuit pattern on a resist layer that has been pre-coated on the surface of the copper foil.
7. FPC board etching, resist stripping
The etching process is not exactly the same as the wet treatment process mentioned above. During the etching process, the mechanical strength of the flexible printed board will change greatly. This is because most of the copper foil is etched away, so it is softer, so it is designed for Special attention should be paid to this when the etching machine of the flexible printed circuit board.
8. Processing of FPC board cover film
One of the unique processes of the flexible printed circuit board manufacturing process is the processing procedure of the cover layer. There are three types of processing methods for the covering film, screen printing of the covering layer, and photo coating layer.
Recently, newer technologies have been developed to expand the range of options.
9. FPC board surface electroplating
9. 1 FPC board plating
9.2 Thickness of FPC board plating
9.3 Stain and dirt of FPC board plating
9.4 FPC electroless plating
9.5 FPC board hot air leveling
10. FPC board shape and hole processing
Most of the processing of the hole and shape of the flexible printed board is processed by punching. However, it is not the only method. Depending on the situation, various methods or combinations can be used for processing. Recently, new processing technologies have been introduced with the demand for higher precision and diversification. New fpc assembly manufacturer covers more optional process flow.
11. Processing of FPC Reinforced Board
Reinforced boards are unique to flexible printed boards, and their shapes and materials used are also diverse.
Adhesives are generally film-like, and the two sides are protected by a release film. The adhesive film with one side of the release film is attached to the reinforcement board, and then the shape and hole are processed, and then it is laminated with the flexible printed board by the hot roll lamination method.
12. FPC board inspection
There are many inspection items for flexible printed board FPC because the rigid printed board PCB board only serves as an electrical connection, and the flexible printed board FPC not only has the same function as the rigid printed board PCB board, but also has foldable, The function of bending motion, so this mechanical performance must also be checked to ensure quality.
mondo technology can also meet with the general fpc manufacturer requirement needs. If you want to know more about flexible printed circuit manufacturer industry information, you can bookmark our blog.
New fpc assembly manufacturer, One-stop FPC SMT manufacturing solution
Compared with general fpc manufacturers, New fpc assembly manufacturer, One-stop FPC SMT manufacturing solution has a more intimate service, can provide one-way service, customize more suitable production process according to customer needs, improve product quality, and be stricter quality control, It can also save costs for customers and let customers worry.
One-stop FPC SMT manufacturing solution
According to the special properties of the product, the number of components and the placement rate, it is appropriate to use a medium and high-speed placement machine for placement. Because there are optical marks for positioning on each piece of FPC, there is a big difference between the upward SMD placement on the FPC and the upward placement on the PCB.
It should be noted that although the FPC is fixed on the carrier board, its appearance may not be as flat as the PCB hard board. There will definitely be some holes between the FPC and the carrier board. Therefore, the suction nozzle is lowered and the pressure of the atmosphere is blown.
The force, etc. needs to be set very accurately, and the nozzle moving speed needs to be reduced. At the same time, the majority of FPC is connected to the board, and the yield of FPC is relatively low, so it is normal for the whole PNL to contain partial bad PCS, which requires the placement machine to have the BAD mark identification function, otherwise, in the production of such Under the condition that the non-integrated PNL is a good board, the production rate will be greatly reduced.
New fpc assembly manufacturers have richer and stronger fpc process capabilities.
Reflow soldering of FPC
It should be considered appropriate to use a forced hot air convection infrared reflow oven, so that the temperature on the FPC can change more evenly, reducing the initiation of poor welding. If the single-sided tape is used, since it can only fix the four sides of the FPC, the half-middle part is deformed under the condition of hot air, and the pad is easy to be tilted, and the molten tin (liquid tin at high temperature) will flow and initiate empty welding and continuous welding. , tin beads, so that the poor rate of the process is higher.
1) Temperature curve test method
Because the heat absorption of the carrier board is different, the types of components on the FPC are different, the temperature rises at different speeds after being heated during the reflow soldering process, and the calories used for reference are also different. The temperature curve has a great influence on the welding quality.
A more appropriate method is to place two FPC-equipped carrier boards on the front and back of the test board according to the actual production carrier board spacing, and attach components to the FPC of the test carrier board, and use high-temperature solder wire to test the temperature.
The probe is soldered on the test place, and the probe wire is fixed on the carrier board with high temperature tape. Note that the high temperature tape should not cover the test area. The place where the test is performed should be selected near the solder joints and QFP pins on all sides of the carrier board, and the final result of such a test can better reflect the real situation.
2) Setting of temperature curve
In the furnace temperature adjustment, since the temperature uniformity of FPC is very poor, it is best to use the temperature curve form of heating/warm-keeping/reflow as appropriate, so that the parameters of each temperature zone are easy to control, and additional FPC and components are subject to thermal shock. The impact should be smaller.
According to experience, it is best to adjust the furnace temperature to the lower limit of the technical requirements of the solder paste. The wind speed of the reflow furnace is generally considered appropriate, and the lowest wind speed that the furnace can consider suitable is used. The chain of the reflow furnace is more stable. Shake is not allowed.
Inspection, testing and sub-board of FPC
Because the carrier plate absorbs heat in the furnace, especially the aluminum carrier plate, the temperature is high when it is released from the furnace, so it is best to increase the cooling fan at the furnace outlet to help reduce the temperature quickly. At the same time, operators need to wear heat-insulating gloves to avoid being burned by the high-temperature carrier plate.
When taking the soldered FPC from the carrier board, use even force and do not use brute force to prevent the FPC from being torn or creased.
The removed FPC should be visually inspected under a magnifying glass of more than 5 times, focusing on problems such as residual glue on the surface, discoloration, tin dip on gold fingers, tin beads, IC pin empty soldering, and continuous soldering.
Because the appearance of the FPC cannot be very flat, the false positive rate of the AOI is high, so the FPC is generally uncomfortable to cooperate with the AOI investigation, but with the help of a special test fixture, the FPC can complete the ICT and FCT tests.
Trace width advantage
One of the great advantages of FPC technology is maintaining high line widths, thereby increasing performance.
This performance improvement is significant for wireless applications. There is a significant difference between the time it takes for a radio signal to travel from one point on a circuit board to another and the time it takes for the signal to be disturbed by noise and interference.
Higher line widths can enable greater signal integrity by reducing these delays while increasing data rates and transmission range. Another benefit of FPC technology is the low dielectric constant (low εr).
PET allows for smaller trace widths and higher performance than other materials such as FR-4. Using low εr in FPC traces also reduces line width variation, thereby improving signal integrity.
Electrical Characteristics
FPC offers several electrical advantages, mainly due to the use of PET.
As mentioned earlier, PET is a low-dielectric material, so FPC using PET can achieve lower line width variations. Reducing linewidth variation improves noise immunity and signal integrity.
FPC also allows for easy wiring, which increases manufacturing yield. Low temperature co-fired ceramics and silica gel also contribute to the FPC process. It provides enhanced thermal performance to the circuit.
The most common FPC fabrication method is transfer printing. That’s because it involves transferring e-ink onto a surface. Parts of the surface are then etched away to create the circuit. Transfer printing allows very high-speed processing capabilities.
We may need circuits that support wireless communication.
Summarize
fpc assembly manufacturer can provide more and more refined fpc manufacturing process to enhance product quality and ensure the integration of services.
Ordinary manufacturers cannot provide smt services, which will make customers have to find other manufacturers to meet smt services, which will increase communication costs and production cycles, and will also cause hidden dangers to product quality.
All these explain above, sure you have understand the whole fpc assembly manufacturer and fpc manufacturer.
If you are wondering where to find a professional fpc assembly manufacturer, you can contact mondo technology. I believe we can provide you with satisfactory service. According to your needs, mondo technology can choose whether to include smt service, one-stop service, or just assembly.