Introduction to HDI Production Process Knowledge

CATALOG

■ Definition of HDI

■ Category of HDI

■ Explanation of HDI Layer

■ HDI Production Process Explanation

■ HDI Key Quality Standard Indicators

Definition of HDI

HDI: High density interconnect

● Able to achieve higher wiring density;

● Reduce the pad area, hole to hole distance and PCB size;

● Reduce the loss of electrical signals.

● https://www.richpcba.com

● Shenzhen Rich Full Joy Electronics Co.,ltd

Category of HDI

HDI: laser drilling

Mechanically drilling blind/buried via

• By laminates:

  ● 1 layer HDI

  ● 2 layers HDI

  ● 3 layers HDI

• By structure:

  ● hole stacking

  ● dislocation

• By processing:

  ● laser

  ● mechanical

Mechanically drilling blind/buried via

• 

  Stack-up times:                 3

  Buried/Blind via times:    5

• 

  Buried/Blind via times:     5

Laser drilling blind/buried via

HDI: laser drilling

How to distinguish the layer of HDI

Buried via: Buried inside the board that can’t be seen from the outside

Blind via: Can be seen from the outside but can’t be seen through

Number of layer: From one end of the board, the number of blind vias of different types can be determined as the layer number

Times of pressing: Count the times that blind/buried vias pass through multiple core boards or dielectric layers

How to distinguish the layer of HDI

Can you count how many layers blind via the below is?

How to distinguish the layer of HDI

HDI Production Process Explanation

• Inner layer 1

  

• Pressing 1

  

• Drilling 1

  

• Pressing 2 complete

  

• Pressing 2

  

• Inner layer 2

  

• PTH1/PP

  

• Drilling 2

  

• Laser drilling 1

  

• PTH/PP2

  

HDI Production Process Explanation

● Laser drilling

● Conformal mask

● Large window

● Direct resin drill

• 

  Conformal mask

• 

  Large window

• 

  Direct resin drilling

HDI Production Process Explanation

• ● 1. Conformal mask

  ● The appearance of the hole has a goodlooking

  ● Limited compensation for misalignment

  ● When the spacing is small enough, it is not possible to increase the aperture

  ● 2. Large window

  ● More compensation for misalignment

  ● There is a stepped phenomenon on the solder pad

  ● When the spacing is small enough, it is not possible to increase the aperture

• ● 3. Direct resin drilling

  ● Remove all copper foil by etching before drilling

  ● Able to drill small spacing

  ● Low cost

  ● Difficulty in laser positioning

  ● Low bonding force

• 

  The hole is too small

• 

  Optimal hole size

• 

  The hole is too big

HDI Key Quality Standards

● The hole shape should have a goodlooking after laser drilling: hole bottom/top ≥0.5

● Hole copper thickness ≥15um

● No residual resin is allowed at the bottom of the hole

● Resin depression at the hole opening of the window opening method ≤10um

HDI Key Quality Standards

HDI Key Quality Standards