PCB Technical - Detailed explanation of HDI board CAM production method

As the HDI board adapts to the development of highly integrated integrated circuits and high-density interconnect assembly technology, it has pushed PCB manufacturing technology to a new level and has become one of the biggest hot spots in PCB manufacturing technology! In all kinds of PCB CAM production, people engaged in CAM production agree that HDI mobile phone boards are complicated in shape, high in wiring density, difficult to produce, and difficult to complete quickly and accurately! Facing the high-quality and fast delivery requirements of customers, I share with all CAM colleagues through continuous practice, summary and experience.

First, how to define SMD is the first problem in CAM production?

In the PCB production process, graphics transfer, etching and other factors will affect the final graphics. Therefore, in CAM production, we need to compensate the production line and SMD separately according to customer acceptance standards. If we incorrectly define SMD, some products may appear SMD is too small. "Users usually design 0.5mm CSP on HDI board mobile phone boards. The size of the pad is 0.3mm. Some CSP boards have blind holes. The spacers corresponding to the blind holes are only 0.3mm, making the CSP pad and the blind hole corresponding pad overlap or Crossed together. In this case, you must be careful not to make mistakes. (Take genesis2000 as an example)

Specific production steps:

1. Close the hole layer corresponding to the blind hole and the buried blind hole.

2. Define SMD.

3. Use the FeaturesFilterpopup and Referenceseleconpopup functions to find the pads containing blind holes from the top and bottom layers, respectively. The moving layer and the b layer are respectively.

4. Using the Referenceseleconpopup function in the t layer (the layer where the CSP pad is located), select and delete the 0.3mm pad with blind via phase contacts, and delete the 0.3mm pad in the top CSP area, according to the customer-designed CSP pad Size, position and quantity, make a CSP and define it as SMD, then copy the CSP pad to the top layer, and add the corresponding pad to the blind hole of the top layer. Layer B is made in a similar way.

5. Find other missing definitions or multiple definitions of SMD according to the network files provided by the customer

Compared with the traditional production method, the purpose is clear, the steps are few, misoperation can be avoided, and it is fast and accurate!

Second, removing the non-functional keyboard is also a special step in the HDI board.

Taking the ordinary eight-layer HDI as an example, remove the non-functional pads corresponding to 2≤7 layers of through holes, and then remove the non-functional pads corresponding to 3≤6 layers of 2≤7 buried holes.

These steps are as follows:

1. Use the NFPRemovel function to remove the non-metallic holes on the top and bottom layers.

2. Close all drilling layers except holes, and remove 2≤7 layers of non-functional solder pads from RemoveundrilLEDpad that does not select the NFPRemovel function.

3. Close all drilling layers except for 2 ≤ 7 buried holes, and select NO in the NFPRemovel function to remove 3 layers of non-functional solder pads from the 3 layers ≤ 6 non-functional solder pads of NO.

Using this method to remove non-functional mats is clear and easy to understand, and is most suitable for people who are just engaged in CAM production.

Third, about laser drilling:

The blind holes of HDI mobile phone boards are generally about 0.1mm micro-holes. Our company uses CO2 laser. Organic materials can strongly absorb infrared rays. Through the thermal effect, the holes are ablated, but the infrared absorption rate of copper is very small, and the copper melting point is high. The CO2 laser cannot ablate copper foil, so the "consistent mask" process is used to etch the copper at the laser hole position (the CAM needs to make an exposed film). At the same time, in order to ensure that the secondary outer layer (the bottom of the laser hole) has copper skin, the distance between the blind hole and the buried hole must be at least 4 meters. Therefore, we must use analysis/Fabrican/plate-drill-check to find out the holes that do not meet the conditions.

Fourth, plug hole and solder mask:

In the layered structure of HDI board, RCC materials are generally used for the secondary outer layer, where the thickness is thinner and the rubber content is small. The process test data shows that when the thickness of the finished plate is greater than 0.8mm, the metalized groove is greater than 0.8mm*2.0mm, and the metalized hole is greater than or equal to 1.2mm, two sets of plug hole files must be made. That is, the plugging hole is divided into two times, the inner layer is flattened with resin shovel, and the outer layer is directly connected to the resistance welding ink plug hole before resistance welding. During the resistance welding process, the hole often falls on or beside the SMD. The customer requires that all holes be treated with plug holes, so when the resistance welding exposure shows or exposes half of the holes, it is easy to pour oil. Cam's staff must deal with this matter. Generally speaking, we prefer to remove this hole. If this hole cannot be moved, please follow the steps below:

1. Add the hole position of the open window covered by the sealing welding on the resistance welding layer, and the light transmission point is less than 3 meters on the side of the processed hole.

2. The tactile holes of the resistance welding window will be added to the resistance welding layer, and the light transmission point will be greater than 3mil on the side of the finished hole. (In this case, the customer allows a little ink on the pad)

Fifth, shape production:

HDI boardmobile phone boards are generally provided as puzzle boards, with complex shapes, and customers have CAD drawings. If we use Genebis2000 to draw in accordance with the marks of the customer's drawing, it is very troublesome. We can click "Save As" directly in the CAD format file*. Change "Save as type" to DWG "AutoCADR14/LT98/LT97DXF(*.DXF)" and read*. DXF files read Geneber files in the normal way. When reading the shape, it is quick and accurate to read the size and position of the postal ticket opening, positioning hole, and optical positioning point.

Sixth, milling shape frame processing:

When processing the milling shape boundary, unless the customer requires copper to be exposed in the CAM production, in order to prevent the sheet from turning the copper skin, according to the production specification, a little copper skin must be cut on the boundary, so the situation shown in Figure 2A will inevitably occur ! "If both ends of A do not belong to the same network, and the width of the copper is less than 3mil (may not be able to make a graph), it will cause an open circuit. These problems were not found in the genetic analysis in 2000, so a replacement must be found Method. We can do a network comparison again, and in the second comparison, we will rely on the edge of the copper skin to cut 3Mili boards. If the comparison result is not open, it means that both ends of A belong to the same network or the width is greater than 3mil( Graphics can be made). If there is an open road, widen the copper skin.