PCB News - PCB unsupported holes and contact pads

PCB unsupported holes and contact chip defects and quality control standards

1. Non-supporting hole halo

Halo: Cracking or delamination on the surface or under the surface of the PCB substrate caused by mechanical processing; it is usually manifested as a white area around the hole or other mechanically processed parts, or two places at the same time. .

No halo state

• No halos.

Acceptable conditions for PCB halo

Acceptable conditions-level 3, 2, 1

• When the edge distance design conforms to IPC-2222, the distance between the halo penetration and the nearest conductive pattern shall not be less than the minimum lateral conductor spacing,

If not specified, it is not less than 100 μm [3,937 μin].

• When the edge distance design does not comply with IPC-2222, it is determined by the PCB manufacturer and the user through negotiation.

Does not meet the conditions-Level 3, 2, 1

• The defect does not meet or exceed the above requirements.

2. Printed contact piece

2.1 Surface Plating-Edge Connector Landing

Target conditions-Level 3, 2, 1

• There are no pits, indentations, scratches, pinholes and surface nodules on the edge connector connection plate.

• There is neither exposed copper nor coating overlap between the solder coating or solder mask and the end coating.

• Surface defects in the intact area do not expose the underlying metal.

• There is no splattered solder or tin-lead plating in the intact area.

• There are no nodules and metal bumps in the intact area.

• The longest dimension of pits, indentations or depressions outside the intact area shall not exceed 0.15 mm [0.00591 in]. There are no more than 3 defects on each contact piece, and the contact pieces with these defects do not exceed 30% of the total number of contact pieces.

• The electrical test "probe indentation" in the intact area meets the final surface coating requirements.

Note 1: The intact area refers to the area of 80% width and 90% length of the center of the connecting plate. Note 2: Spilled solder or exposed nickel/copper.

Note 3: Electric test probe indentation.

Note 4: Pockmarks, indentations or depressions.

Note 5: Cuts and scratches.

Acceptable conditions-level 3 (exposed copper/overlapping area)

• The exposed copper/plating overlap area is less than or equal to 0.8 mm [0.031 in]. Color difference is allowed in the overlapping area.

Acceptable conditions-level 2 (exposed copper/overlapping area)

• The exposed copper/plating overlap area does not exceed 1.25 mm [0.04921 in]. Color difference is allowed in the overlapping area.

Acceptable conditions-level 1 (exposed copper/overlapping area)

• The exposed copper/plating overlap area does not exceed 2.5 mm [0.0984 in]. Color difference is allowed in the overlapping area.

Not eligible-level 3, 2, 1

• The defect does not meet or exceed the above requirements.

2.2 Surface Plating-Rectangular Surface Mount Land

Target conditions-Level 3, 2, 1

• There are no gaps, indentations, nodules or pinholes on the outer edge of the connecting plate or inside the connecting plate.

Acceptable conditions-Level 3, 2

• Surface imperfections along the outer edge of the connecting pad must not exceed 20% of the length or width of the connecting pad.

•Surface defects along the outer edge of the connecting plate cannot encroach on the area of 80% of the length and 80% of the width of the center of the connecting plate.

• The surface defects inside the connecting plate cannot exceed 10% of the length or width of the connecting plate.

• The electrical test "probe indentation" in the intact area meets the final surface coating requirements.

Acceptable conditions-level 1

• Surface imperfections along the outer edge of the connecting pad must not exceed 30% of the length or width of the connecting pad.

•Surface defects along the outer edge of the connecting plate cannot encroach on the area of 80% of the length and 80% of the width of the center of the connecting plate.

• The surface defects inside the connecting plate cannot exceed 20% of the length or width of the connecting plate.

• The electrical test "probe indentation" in the intact area meets the final surface coating requirements.

Not eligible-level 3, 2, 1

• The defect does not meet or exceed the above requirements.

2.3 Surface Plating-Round Surface Mounting Land (BGA)

Target conditions-Level 3, 2, 1

• No nicks, indentations, nodules or pinholes on the outer edge of the connecting plate.

Acceptable conditions-level 3,2

Acceptable conditions-Level 3, 2

• Surface imperfections along the outer edge of the connecting pad cannot extend to the center of the connecting pad for more than 10% of the diameter of the connecting pad.

• Surface imperfections along the outer edge of the connection disk must not extend beyond 20% of the circumference of the connection disk.

• There is no surface defect in the 80% area of the diameter center of the connecting plate.

• The electrical test "probe indentation" in the intact area meets the final surface coating requirements.

Not eligible-level 3, 2, 1

• The defect does not meet or exceed the above requirements.

2.4 Surface Coating-Metal Wire Bonding Pad

Target conditions-Level 3, 2, 1

• After testing according to the applicable test method negotiated by the supplier and the buyer, the wire bonding pad has no surface nodules, roughness, probe indentation or probe indentation exceeding 0.8 μm [32 μin] RMS (root mean square value) in the intact area. Scratches. If using IPC-TM-650 test method 2.4.15, in order to obtain the root mean square value in the intact area, it is recommended to adjust the roughness cut width to approximately 80% of the maximum length of the wire bond pad. For more information about surface roughness, please refer to ASME B46.1.

•The definition of intact area is based on the center of the wire bond pad, the area within the range of 80% of the length of the wire bond pad and 80% of the width (see Figure 20 below).

Not eligible-level 3, 2, 1

• The defect does not meet or exceed the above requirements.

2.5 Edge burrs of PCB printed contacts

Target conditions-Level 3, 2, 1

• Smooth edges.

Acceptable conditions-level 3, 2, 1

•Edge conditions-smooth, no burrs, no rough edges, no warping of the coating of the printed contact sheet, no separation (delamination) between the printed contact sheet and the substrate, and no loose fiber on the chamfered edge of the contact sheet. Exposure of copper is allowed at the end of the printed contact piece.

Not eligible-level 3, 2, 1

• The defect does not meet or exceed the above requirements.

2.6 Adhesion of outer coating

Target/acceptable conditions-level 3,2,1

• The tape test proves that the coating has good adhesion and no coating peeling off

Note 1: Conductor width (actual).

Note 2: The conductor width on the production base plate.

Note 3: The broadening of the coating observed from the whole (determined by vertical measurement from above and comparison with the production master).

Note 4: Final plating.

Note 5: Copper.

Note 6: Undercutting observed by manufacturers and users.

Note 7: Coating edges observed by manufacturers and users.

• The defect does not meet or exceed the above requirements.

Note 1: The adhesion of the coating should be tested in accordance with IPC-TM-650 test method 2.4.1. A piece of pressure-sensitive tape is pressed onto the surface of the coating, and then the tape is torn off by hand in the direction perpendicular to the circuit pattern.

Note 2: The plating is adhered to the tape.

The above is the introduction of PCB board non-support holes and contact chip defects and quality control standards. Ipcb also provides PCB manufacturers and PCB manufacturing technology.