General HDI circuit boards use metallized blind holes to connect each circuit layer that needs to be connected. The diameter is generally not greater than 0.2_; then the dielectric layer under the blind hole is removed by a laser ablation process to form a blind hole reaching the upper copper foil layer; then, the blind hole is metallized to realize the two layers of copper foil. Interconnection; then, you can continue to laminate the build-up layer, and use the same method to make metallized blind holes after the build-up layer and use the same method to make metallized blind holes after the build-up layer to realize the interconnection between other layers.

　　The method for making blind holes on an HDI circuit board includes the following steps: ①coating photosensitive epoxy resin; ②baking the circuit board and curing the resin; The epoxy resin at the hole position makes the copper pad of the inner layer pattern prominent; ④ mechanically drill through holes; ⑤ metallization plating; ⑥ chemical etching copper.

　　How to define SMD is the first difficulty in CAM production.

　　In the PCB production process, factors such as pattern transfer and etching will affect the final pattern, so we need to compensate the lines and SMD separately in the CAM production according to the customer's acceptance criteria. If we do not define the SMD correctly, the finished product may appear partially SMD is too small.

　　Specific production steps:

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

　　2. Define SMD

　　3. Use the FeaturesFilterpopup and Referenceselectionpopup functions to find the pads that include blind holes from the top layer and bottom layer, movetot layer and b layer respectively.

　　4. Use the Referenceselectionpopup function on the t layer (the layer where the CSP pads are located) to select and delete the 0.3mm pad that touches the blind hole, and delete the 0.3mm pad in the CSP area of the top layer. Then design the size, position and number of CSP pads according to the customer, make a CSP and define it as SMD, then copy the CSP pads to the TOP layer, and add the pads corresponding to the blind holes on the TOP layer. The b layer is made in a similar way.

　　5. Find out other missing or multi-defined SMDs according to the network file provided by the customer.

　　Plugs and Solder Mask:

　　In the HDI lamination configuration, the secondary outer layer is generally made of RCC material, which has a thin dielectric thickness and a small amount of glue. The process experimental data shows that if the thickness of the finished product is greater than 0.8mm, the metallization groove is greater than or equal to 0.8mmX2.0mm , the metallized hole is greater than or equal to 1.2mm, and two sets of plug hole files must be made. That is, the holes are plugged twice, the inner layer is leveled with resin, and the outer layer is directly plugged with solder mask ink before solder mask. During the solder mask fabrication process, vias often fall on or next to the SMD. The customer requires all vias to be plugged, so the vias with exposed or exposed half of the holes are prone to oil leakage during solder mask exposure.

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