PCB Technical - PCB production skills of automobile circuit board factory: CAM production method of HDI board

Because the HDI board complies with the stagnation of high-integration IC and high-density interconnection technology, it pushes PCB building skills to a new corridor and changes one of the biggest hot spots of PCB building skills!

In the CAM manufacturing of various types of PCBs, the people who deal with CAM manufacturing disagree that HDI mobile phone boards are simple in shape and high in wiring density. CAM manufacturing is more difficult, and it is difficult to quickly and accurately achieve!

Faced with depositors' requests for high quality and fast delivery, I have been theorized and summarized, and I have a little experience about this, and I am sharing with you CAM here.

1. How to define SMD as the first difficulty in CAM manufacturing

In the PCB manufacturing process of the bus route board factory, the graphics transfer, seal cutting and other elements will reflect the final graphics. Therefore, we are in CAM manufacturing according to the depositor’s optometry specifications, and we need to make up for the line and SMD discrimination. If we do not accurately define SMD, The scrap may appear that the overall SMD is too small.

Depositors often envision a 0.5mm CSP in the HDI part of the mobile phone board, the pad size is 0.3mm, and there are blind holes in some CSP pads, and the blind holes are just 0.3mm for the corresponding pads, so that CSP soldering The pad and the blind hole are overlapped or interspersed with the corresponding pads. In this situation, you must operate carefully and beware of mistakes.

(Take genesis2000 as an example) Detailed manufacturing method:

1. Open the blind holes and buried holes to the corresponding drilling layer.

2. Define SMD

3. Use FeaturesFilterpopup and Referenceselectionpopup performance to find the include blind hole pads from the top and bottom layers to distinguish the moveot layer and the b layer.

4. Use the ReferenceselecTIonpopup performance on the t layer (the layer where the CSP pad is located), select and remove the 0.3mm pad that is in contact with the blind hole, and remove the 0.3mm pad in the CSP sea area of the top layer. Then according to the depositor's assumption of the size, position, and number of the CSP pads, I made a CSP and defined it as SMD, and then positively filmed the CSP pads to the TOP layer, and added the pads corresponding to the blind holes on the TOP layer. The b-layer is made in a similar way.

5. Find other SMDs that are not defined or more defined by referring to the depositor's needs. Compared with the conventional manufacturing method, the method is clear and the method is less. This method can prevent misoperation, fast and accurate!

2, the removal of non-performance pads is also a special method in the mobile phone board of the HDI department

Take the general eight-layer HDI as an example. First, remove the non-performance pads corresponding to the through holes in the 2--7 layers, and then remove the 2--7 buried holes in the 3--6 layers. Of non-performance pads.

The method is as follows:

1. Use NFPRemovel performance to remove the non-metallized holes of the top and bottom layers corresponding to the corresponding pads.

2. Open all drilling layers except through holes, choose NO for RemoveundrilLEDpads in NFPRemovel performance, and remove 2-7 layers of non-performance pads.

3. Open all the drilling layers except for the buried holes in the 2-7 layers, choose NO for the Removeundrilledpads in the NFPRemovel performance, and remove the non-performance pads in the 3-6 layers. Adopting this method to go to non-performance pads, with clear thoughts and simple understanding, is most suitable for personnel who have just dealt with CAM manufacturing.

3. For laser drilling

The blind holes of HDI mobile phone boards are normally 0.1mm micro-holes inside and outside. Our company adopts CO2 Lyser. Inorganic materials can strongly attract infrared rays. After thermal effects, they are ablated into holes. However, the attraction rate of copper to red inner wires is very small. Moreover, because of the high melting point of copper, the CO2 laser has no choice but to ablate the copper foil, because the "conformalmask" process is used to engrave the copper skin of the laser drilling hole with a seal engraving liquid (the CAM needs to make an exposed film).

Simultaneously, in order to ensure that there is a copper skin at the secondary periphery (the bottom of the laser hole), the distance between the blind hole and the buried hole must be at least 4mil. For this reason, we must use Analysis/FabricaTIon/Board-Drill-Checks to find a satisfactory environmen ttrue position. The hole position.

4, plug hole and solder mask

In the HDI lamination configuration of the bus route board factory, the sub-periphery normally adopts RCC data, the thickness of the medium is small, and the amount of glue is small. The process test data indicates that if the thickness of the scrap plate is greater than 0.8mm, it is non-metallic. If the slot is greater than or equal to 0.8mmX2.0mm, and the non-metallized hole is greater than or equal to 1.2mm, two sets of plug hole materials must be made.

That is, the holes are plugged twice, the inner layer is flattened with resin, and the outer layer is indirectly plugged with solder mask ink before the solder mask. In the solder mask manufacturing process, there are often vias falling on or next to the SMD. Depositors request all vias to be plugged, because the solder mask is exposed during solder mask exposure or the vias that reveal half of the hole simply leak oil.

The CAM staff must solve this problem. Under normal conditions, we would first remove the vias. If they have no choice but to move the vias, follow the next method:

1. Add a light leakage point that is 3MIL smaller than the scrap hole on the solder mask layer for the via hole position that is opened by the solder mask Covered window.

2. Add a light leakage point that is 3MIL larger than the waste hole on the solder mask layer to the via hole position of the touch window. (Under this situation, the depositor promises to put a little ink on the pad)

5, shape manufacturing

The mobile phone board of the HDI PCB department is normally delivered in jigsaw, simple in shape, and the depositor is attached with a piece of jigsaw form of CAD drawings. If we use genesis2000 to stop drawing according to the punctuation of the depositor's drawing, it will be quite troublesome. We can indirectly click "Save As" in the CAD system data *.dwg to change the destruction type to "AutoCADR14/LT98/LT97DXF (*.DXF)" and then stop reading *.DXF data in the form of malformed reading genber data . The simultaneous sound of the shape is being read, and the size and position of the stamp hole, positioning hole and optical positioning point are read quickly and accurately.

6, milling shape frame solution

When solving the problem of milling the frame, in CAM manufacturing, in addition to the depositor’s request, the copper must be exposed. In order to prevent the copper from turning over the edge of the board, in accordance with the manufacturing standard, it is requested to cut a little copper into the board from the frame. Status shown!

If both ends of A do not belong to the same network, and the copper width is less than 3mil (can be done without graphics), it will cause an open circuit.

I can't see such results in the comprehensive speech of genesis2000, so it is necessary to blaze a new trail. We can do one more network comparison, and in the second comparison, the copper of the frame will be cut into the board by 3mil. If the result of the comparison is not open, it indicates that both ends of A belong to the same network or the amplitude is greater than 3mil (can do Into graphics). If there is an open circuit, widen the copper sheet.