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Remove bases and cover-lay sat working-size, as directed in the work instructions, using an automatic cutting machine. Measure and record whether the specifications, dents and scratches correspond, and check cracks and panel quantity to reduce defective products after drilling.
Drilling holes in bases, cover-lays, and stiffening plates with a CNC drill machine. FPCB, a flexible PCB base, has a P.I and glue gun between the copper foils, unlike general PCBs, so it is an important index for reducing burrs incurred by the speed and drill beat conditions as much as possible.
A process applying a through-hole via electric current through the chemical or electric department by connecting a circuit on the other side of a multi-layered or double-sided PCB. (Bronze plating is not necessary for double or single-faced exposures) The bronze plating must be done within limits not harming FPCB flexibility. There should also be virtually no PNL contraction after completion, and chemical management and continuous maintenance of equipment must be carried out.
When bronze plating is completed, microscopic projections or other substances may adhere. A brushing and pickling process must be carried out to remove these substances and clean the bronze plating surface. Removing foreign substances and ensuring an even bronze plating surface is part of the process, but the main focus is in reducing defective products (disconnection, voids, or pinholes) by improving the dry-film adhesiveness in the dry-film welding process (D/F).
A preparation process to create a pattern on the board surface, and a to weld a photosensitive polymer film to the board, which compresses the dry-film through a heat-compression roller. Proper temperature and pressure (105C 10C, 3~3.5Kg/cm in general) is critical, and a speed varying only 0.7~0.9 m/min is critical depending on product when the roller speed is applied. If these conditions are not met, defective patterns and hole explosions can occur.
After coating dry-film with a light exposure film to form a circuit, a pattern is formed by hardening the necessary circuits via UV. When UV light from the lamp is reflected on the board via reflectors, and the area receiving light through the light exposure film is hardened, the light exposure should be 35~40mj/cm, the vacuum free pressure should exceed 55~75cmhg, the level of illumination should be 3~9 mW/cm, and the lamp change should be 7,000 Hit.
Eliminating dry-film not exposed to UV during exposure through a chemical method. The concentration of liquid should be 1% soda ash, and the temperature should be maintained at 30~33, with a proper pressure of 1.0~1.5kg/cm. Residue accumulating in developing (D/F residue) should be removed by spraying water of consistent pressure and consumption products should be properly managed.
Completely eliminate unnecessary bronze circuit plating for each product via etching solution. Exposed bronze plating is etched with an etching solution. The portion where dry-film remains protects the circuit performing the role of register. Etching speed depends on product type, and circuit characteristics. If the speed is slow, it may cause opening due to over-etching and if too fast, the danger of shorting increases due to non-etching. Proper management is therefore necessary.
Completely eliminate remaining dry-film where the circuit has been formed with a desquamation liquid having a strong alkali. Hardened dry-film does not dissolve in weak alkali, but dissolves easily in strong alkali. If the desquamation liquid or concentration temperature is low, the dry-film fails to completely desquamate, and becomes a key cause of adulteration with foreign substances. If the temperature is too high, it becomes a cause of incurred oxidation.

Portions requiring component loading on boards or insertion of connectors should have an opened cover-lay, however, portions not requiring such should be left intact to protect the pattern, and the process window manufacturing process is used at this time, with a press to protect the pattern. To punch the cover-lay, a mold or wooden pattern with a consistent guide is required, and considerable deviation occurs depending on tool accuracy. It is thus important to work only after determining accuracy after punching.
The process of attaching and detaching cover-lay films on the base which has formed a pattern after completion of window manufacturing, and temporarily welding such to fit the point as the heading element prior to lamination. The ratio of the manufactured window portion, base leader line, and blind spot point for welding must be 1:1.To achieve this ratio, highly skilled craftsmen are required. This process may significantly affect subsequent processes.

The process of laying-up products which have completed welding to correspond to the characteristics of each model, using materials necessary for lamination. The initial pressure, main pressure, and temperature are set, completely hardening and welding the base and cover-lay. All processes are important but the lamination process is particularly important because product quality is primarily determined at this stage. Thus, prior to mass production, it is helpful to review many tests and set the hot-press conditions exactly, and check resin flow, delamination, and thermal shock.
To manufacture the external form, press work is needed, which in turn requires a hole for guidance. This guide-hole comes in two types, 2.0 and 3.2, and drilling of the guide-hole is called finishing manufacturing. Rather than pre-manufacturing (early drilling), products having an eccentric socket or serious contraction may apply finishing manufacturing.

The exposed side of all FPCB products requiring soldering, connector insertion, or component loading are all made of pure bronze. This process designates welding of Au or Pb however, which are easier to solder and more sensitive to electric response on bronze plating. In general classification, this process can be divided into gold electroplating, gold non-electroplating, lead electroplating, and lead non-electroplating. Products sensitive to electricity are handled via gold electroplating or non-electroplating, and the surfaces of products requiring soldering or SMT are handled by electroplating or non-electroplating using lead. However, due to regulations on lead use due to its toxicity, surface treatment is handled with lead free products.
This process uses a printing technique, with ink on minute parts difficult for cover-lay manufacturing, or on leader lines necessary for each product element or model. The marking color is generally white, but black or yellow are used as well. Standard products are PSR, which covers areas hard to handle with cover-lay, by covering with ink when inserting model name, and Matt Black, which prevents light penetration in BGA, which is a type of SMT. Considerable caution is required as contraction may occur in the drying process after printing, depending on product.

The flexibility of FPCB Flexile Printed Circuit Board, causes difficulty in determining the true product length in the short range, unlike PCB. Therefore, a stiffening plate of a certain thickness is required at the rear of the component loading side. This process is for manually attaching each product after plate manufacturing. The glues used are thermosetting and decompressing glue. The latter is rather simple, whereas the former requires long hours of heat and pressure to attach, and caution is required with the difference on borderlines between portions having a stiffening plate and those not having a plate.
This process is required for products which have undergone electroplating. As all PNL products are connected with a lead track, if the products are not disconnected via PCS, the products will be judgedshort in the BBT process. This process is for disconnecting the lead track. The mold is a PIERCING mold, which punches portions otherwise difficult to punch in the G2 guide, external form, and apparatus holes.

A process checking for defective products by deciphering open (disconnection) and short (overlapping circuits) areas of a pattern. A guide hole for BBT and Press is required, and accuracy may be lacking depending on voltage. Thus, when the voltage is low, the speed is low but accuracy is high, and when the voltage is high, the speed is high but the error rate in deciphering open and short increases. Press External Form Manufacturing Process This is the final stage of product completion, and is for forming and punching individual products corresponding to the form and size of the external form required by customers. Caution should be exercised that all punching is exactly the same. Product quality depends on the polish condition of the mold. For special products therefore, scratches or burrs on products are prevented by treating the mold with a special coating.
This is the user customized finishing process for each product, using a press to form outer dimensions and shape. In this process quality varies, depending on mold grinding conditions. For special cases scratches and burrs can be prevented by applying a special coating to the mold.
This is the final inspection process for sorting good and flawed products via microscope in every piece or panel from the finishing press. It is critical to standardize each inspectors capabilities. This process requires constant training and standardized inspection specifications.
After final inspection and before shipping, a dimension and specification verification process for every feature is carried out in reference to the original design. - If an effect is found in the QA process, the product is moved back to final inspection, otherwise it moves forward to the packing stage.
Quantities are checked with an electronic weight scale and inner packing verification according to customer specifications. The product is then packed in its case and outer box for shipping. Shipping is carried out after affixing an accurate product label, bar code, and other required labels depending on customer requirements.