PCB pressing common problems

1. White, revealing the texture of the glass cloth

problem causes:

1. The resin fluidity is too high;

2. The pre-pressure is too high;

3. The timing of adding high pressure is incorrect;

4. The resin content of the bonding sheet is low, the gel time is long, and the fluidity is great;

Larutan:

1. Reduce temperature or pressure;

2. Reduce pre-pressure;

3. Carefully observe the resin flow during lamination, after the pressure change and temperature rise, adjust the starting time of applying high pressure;

4. Adjust the pre-pressure\temperature and the start time of high pressure;

Two, foaming, foaming

problem causes:

1. The pre-pressure is low;

2. The temperature is too high and the interval between pre-pressure and full pressure is too long;

3. The dynamic viscosity of the resin is high, and the time to add full pressure is too late;

4. The volatile content is too high;

5. The bonding surface is not clean;

6. Poor mobility or insufficient pre-stress;

7. The board temperature is low.

Larutan:

1. Increase the pre-pressure;

2. Cool down, increase pre-pressure or shorten pre-pressure cycle;

3. The time-activity relationship curve should be compared to make the pressure, temperature and fluidity coordinate with each other;

4. Reduce the pre-compression cycle and reduce the temperature rise rate, or reduce the volatile content;

5. Strengthen the operation force of cleaning treatment.

6. Increase the pre-pressure or replace the bonding sheet.

7. Check the heater match and adjust the temperature of the hot stamper

3. There are pits, resin and wrinkles on the board surface

problem causes:

1. Improper operation of LAY-UP, water stains on the surface of the steel plate that have not been wiped dry, causing the copper foil to wrinkle;

2. The board surface loses pressure when pressing the board, which causes excessive resin loss, lack of glue under the copper foil, and wrinkles on the surface of the copper foil;

Larutan:

1. Carefully clean the steel plate and smooth the surface of the copper foil;

2. Pay attention to the alignment of the upper and lower plates with the plates when arranging the plates, reduce the operating pressure, use low RF% film, shorten the resin flow time and speed up the heating speed;

Fourth, the inner layer graphics shift

problem causes:

1. The inner pattern copper foil has low peeling strength or poor temperature resistance or line width is too thin;

2. The pre-pressure is too high; the dynamic viscosity of the resin is small;

3. The press template is not parallel;

Larutan:

1. Switch to high-quality inner-layer foil-clad board;

2. Reduce the pre-pressure or replace the adhesive sheet;

3. Adjust the template;

Five, uneven thickness, inner layer slippage

problem causes:

1. The total thickness of the forming plate of the same window is different;

2. The accumulated thickness deviation of the printed board in the forming board is large; the parallelism of the hot-pressing template is poor, the laminated board can move freely, and the entire stack is off the center of the hot-pressing template;

Larutan:

1. Adjust to the same total thickness;

2. Adjust the thickness, choose copper clad laminate with small thickness deviation; adjust the parallelism of the hot-pressed film board, limit the freedom of multi-response for the laminated board, and strive to place the laminate in the central area of ​​the hot-pressed template;

Six, interlayer dislocation

problem causes:

1. The thermal expansion of the inner layer material and the resin flow of the bonding sheet;

2. Heat shrinkage during lamination;

3. The thermal expansion coefficient of the laminate material and the template are quite different.

Larutan:

1. Control the characteristics of the adhesive sheet;

2. The plate has been heat-treated in advance;

3. Use inner layer copper clad board and bonding sheet with good dimensional stability.

Seven, plate curvature, plate warpage

problem causes:

1. Asymmetric structure;

2. Insufficient curing cycle;

3. The cutting direction of the bonding sheet or the inner copper clad laminate is inconsistent;

4. The multi-layer board uses plates or bonding sheets from different manufacturers.

5. The multilayer board is improperly handled after post-curing and releasing pressure

Larutan:

1. Strive for symmetrical wiring design density and symmetrical placement of bonding sheets in lamination;

2. Guarantee the curing cycle;

3. Strive for consistent cutting direction.

4. It will be beneficial to use materials produced by the same manufacturer in a combined mold

5. The multilayer board is heated to above Tg under pressure, and then kept under pressure and cooled to below room temperature

Eight, stratification, heat stratification

problem causes:

1. High humidity or volatile content in the inner layer;

2. High volatile content in the adhesive sheet;

3. Pollution of the inner surface; pollution of foreign substances;

4. The surface of the oxide layer is alkaline; there are chlorite residues on the surface;

5. The oxidation is abnormal, and the oxide layer crystal is too long; the pre-treatment has not formed enough surface area.

6. Insufficient passivation

Larutan:

1. Before lamination, bake the inner layer to remove moisture;

2. Improve the storage environment. The adhesive sheet must be used up within 15 minutes after being removed from the vacuum drying environment;

3. Improve the operation and avoid touching the effective area of ​​the bonding surface;

4. Strengthen the cleaning after the oxidation operation; monitor the PH value of the cleaning water;

5. Shorten the oxidation time, adjust the concentration of the oxidation solution or operate the temperature, increase the micro-etching, and improve the surface condition.

6. Follow the process requirements