PCB Technical - PCB function description and solutions to some problems

PCB performance specification

1. FPC, also known as flexible circuit board, is a highly reliable, flexible printed circuit board made of polyimide or polyester film as the base material. It has the characteristics of high wiring density, light weight, thin thickness and good bendability.

The Chinese name of the flexible circuit board type PCB is a kind of abbreviation of soft board, FPC features light weight, thin thickness and other pre-production processing modifications. During the production process, in order to avoid excessive opening and short circuits, the yield rate is too low or the drilling and rolling are reduced. The FPC board is invalidated due to rough technical questions such as cutting and cutting, and the question of replenishing materials, and evaluating how to choose the material to achieve the function of the customer's flexible circuit board.

Prenatal pretreatment is particularly important. Pre-production pretreatment, there are three aspects that need to be processed, and all three aspects are completed by engineers. The first is FPC board engineering evaluation, mainly to evaluate whether the customer's FPC board can be produced, whether the company's production capacity can satisfy the customer's board manufacturing request and unit cost;

If the project evaluation is passed, the next step is to prepare materials immediately and be satisfied with the supply of raw materials in each production link. Finally, the engineer will process the customer’s CAD structure drawing, gerber line materials and other engineering documents to suit the production environment and production specifications of the production equipment., And then transfer the production drawings and MI (Engineering Process Card) and other materials to the production department, document control, acquisition and other departments, and enter the conventional production process.

Modification of the production process: Double-sided panel cutting - drilling - PTH - electroplating - pre-treatment - dry film application - alignment - exposure - development - pattern plating - film removal - pre-processing - dry film application - alignment exposure - development - etching - take off the film - surface treatment - paste masking film - limit - cure - immerse nickel gold - printed characters - cut - electrical test - punching - final inspection - packaging - shipping order panel opening - drilling - paste dry film -Alignment - Exposure - Development - Etching - Stripping - Appearance Treatment - Masking Film - Restriction - Curing - Appearance Treatment - Immersion Nickel Gold - Printing Characters - Cutting - Electrical Testing - Punching - Final Inspection - Packaging - Shipment

2. Let's talk about the characteristics of the FPC sub-board machine below:

1. Compact structure, strong rigidity, simple and safe operation;

2. A variety of molds can be replaced, and the mold change is convenient and easy;

3. The lower mold is automatically in and out, it is convenient to take and place the product, and the finished product can be dropped into the drawer;

4. Reduce the internal stress generated when cutting the board and avoid tin cracking;

5. The efficiency of punching semi-finished PCB and FPC is extremely high.

Solutions to problems encountered by the circuit board

First of all, we need to understand the corrosion process of PCB circuit boards: the corrosive liquid is usually made of ferric chloride and water. Ferric chloride is a soil solid and easily absorbs moisture in the air, so it should be sealed and stored. When preparing the ferric chloride solution, 40% ferric chloride and 60% water are generally used. Of course, more ferric chloride is used, or warm water (not hot water to prevent the paint from falling off) can make the reaction faster Note that ferric chloride is corrosive. Try not to touch your skin and clothes. Use a cheap plastic basin for the reaction vessel, just fit the circuit board.

Start to corrode the PCB circuit board from the edge. When the unpainted copper foil is corroded, the circuit board should be taken out in time to prevent the paint from eroding away useful circuits. Rinse at this time, and scrape off the paint with bamboo chips by the way (at this time the paint comes out of the liquid and is easier to remove).

If it is not easy to scratch, just rinse it with hot water. Then wipe it dry and polish it clean with sandpaper, revealing the shiny copper foil, and a printed circuit board is ready. In order to preserve the results, the polished PCB circuit boards are usually coated with a rosin solution, which can not only assist the soldering, but also prevent oxidation.