Fumax

Product types: single-sided, double-sided and multi-layer printed circuit boards (PCBs), flexible (soft) circuit boards, buried blind via boards.

Maximum processing size: single panel, double panel: 1000mm * 600mm Multilayer board: 600mm * 600mm
Maximum number of floors: 20 floors
Processing board thickness: Rigid board 0.4mm -4.0mm Flexible board 0.025mm—0.15mm
Base material copper foil thickness: Rigid board 18μ (1/ 2OZ), 35μ ( 1OZ ), 70μ ( 2OZ ) Flexible board 0.009MM 0.018mm 0.035mm 0.070mm 0.010mm
Commonly used substrates
FR-4, CEM-3, CEM-1, 94HB, 94VO, polytetrachlorethylene, polyester, polyimide.

Process capability

(1) Drilling: minimum hole diameter 0.15MM
(2) Hole metallization: minimum hole diameter 0.15mm, plate thickness/aperture ratio 4:1
(3) Width of conductors: Minimum line width: gold plate 0.075mm, tin plate 0.10mm
(4) Wire spacing: Minimum spacing: gold plate 0.075mm, tin plate 0.10mm
(5) Gold-plated plate: Nickel layer thickness: 〉 or =2.5μ Gold layer thickness: 0.05-0.1μm or according to customer requirements
(6) Spray tin plate: Tin layer thickness: > or =2.5-5μ
(7) Milling board: Minimum distance from line to edge: 0.15mm Minimum distance from hole to edge: 0.2mm Minimum shape tolerance: ± 0.12mm
(8) Socket chamfer: Angle: 30 degrees, 45 degrees, 60 degrees Depth: 1-3mm
(9) V cut: Angle: 30 degrees, 35 degrees, 45 degrees Depth: plate thickness 2/3 Minimum size: 80mm * 80mm
(10) Continuity test:
Welding resistance: 85—105℃ / 280℃—360℃
Flexible board bending resistance/chemical resistance: fully in line with international standards
Introduction to thick copper circuit board technology

Pre-plating preparation and electroplating treatment

The main purpose of thickening copper plating is to ensure that there is a thick enough copper plating in the hole to ensure that the resistance value is within the range of process requirements. As a plug-in, it fixes the position and ensures the connection strength; as a surface-mounted device, some holes are only used as conductive holes to conduct electricity on both sides.

Check item

1. Mainly check the metallization quality of the holes, and ensure that there are no excess objects, burrs, black holes, holes, etc. in the holes;
2. Check whether there is dirt or other excess matter on the surface of the substrate;
3. Check the substrate number, drawing number, process documents and process instructions;
4. Understand the mounting parts, mounting requirements and the plating area that the plating tank can bear;
5. The plating area and process parameters must be clear to ensure the stability and feasibility of the electroplating process parameters;
6. Clean and prepare the conductive parts and energize them first to make the solution appear activated;
7. Determine whether the composition of the bath liquid is qualified and the surface area of the plate; if a column-mounted spherical anode is used, the consumption must also be checked;
8. Check the firmness of the contact parts and the fluctuation range of voltage and current.

Quality control of thickened copper plating

1. Accurately calculate the plating area and refer to the impact of the actual production process on the current, correctly determine the required value of the current, grasp the changes in the current during the electroplating process, and ensure the stability of the electroplating process parameters;
2. Before electroplating, first use a debugging board to conduct test plating, so that the bath liquid is in an activated state;
3. Determine the total current flow direction, and then determine the order of hanging boards. In principle, it should be from far to near; ensure the uniformity of current distribution on any surface;
4. To ensure the uniformity of the coating in the hole and the consistency of the coating thickness, in addition to the technological measures of stirring and filtration, impulse current is also required;
5. Frequently monitor the changes in current during the electroplating process to ensure the reliability and stability of the current value;
6. Check whether the thickness of the copper plated layer of the hole meets the technical requirements.

Copper plating process

During the thickening copper plating process, process parameters must be monitored regularly, which often causes unnecessary losses due to subjective and objective reasons. To complete the thickening copper plating process, the following aspects must be achieved:

1. Add a certain value based on the area value calculated by the computer and the empirical constant accumulated in actual production;
2. According to the calculated current value, in order to ensure the integrity of the coating in the hole, a certain value, that is, the impact current, must be added to the original current value, and then return to the original value in a short period of time;
3. When the electroplating of the circuit board reaches 5 minutes, take out the substrate and observe whether the copper layer on the surface and the inner wall of the hole is complete. It is better if all the holes have a metallic luster;
4. A certain distance must be maintained between substrates;
5. When the thickened copper plating reaches the required plating time, a certain amount of current must be maintained during the removal of the substrate to ensure that no blackening or darkening occurs on the surface of the subsequent substrate and in the holes.

Precautions

1. Check the process documents, read the process requirements and be familiar with the substrate machining blueprint;
2. Check whether there are scratches, indentations, exposed copper parts, etc. on the surface of the substrate;
3. Conduct trial processing according to the mechanical processing floppy disk, conduct first-piece pre-inspection, and then process all workpieces if they meet the process requirements;
4. Prepare measuring tools and other tools used to monitor the geometric dimensions of the substrate;
5. Select the appropriate milling tool (milling cutter) according to the nature of the raw material of the substrate to be processed.

QC

1. Strictly implement the first article inspection system to ensure that product dimensions meet design requirements;
2. According to the raw materials of the circuit board, reasonably select the milling process parameters;
3. When fixing the position of the circuit board, clamp it carefully to avoid damaging the solder layer and solder resist layer on the surface of the circuit board;
4. To ensure the consistency of the dimensions of the substrate, the position accuracy must be strictly controlled;
5. When disassembling and assembling, pay special attention to placing paper on the barrier layer of the substrate to avoid damaging the coating layer on the surface of the circuit board.