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CN-122002712-A - Method for forming deep blind hole by laser sintering

CN122002712ACN 122002712 ACN122002712 ACN 122002712ACN-122002712-A

Abstract

A method for forming deep blind hole by laser winding includes providing substrate containing external conducting layer, dielectric layer and target conducting layer, forming copper window on external conducting layer to define an opening, forming first hole wall section in dielectric layer, retaining residual dielectric layer on hole bottom to cover target conducting layer, removing residual dielectric layer and forming second hole wall section to expose target conducting layer on hole bottom, setting hole overlapping configuration region containing multiple hole overlapping points, setting a hole overlapping rate according to center distance between two adjacent hole overlapping points, and applying laser pulse to multiple hole overlapping points in sequence by using independent variable groups of first and second laser sections. Therefore, the processing efficiency of the large blind hole is improved, and the uncertainty of residual materials at the bottom of the hole can be reduced.

Inventors

  • JIA YONGLIN
  • Lou Weika
  • ZHONG HUANHUAN
  • GUO CHAO

Assignees

  • 健鼎（无锡）电子有限公司

Dates

Publication Date
20260508
Application Date
20260309

Claims (10)

  1. 1. A method of forming a deep blind via by laser firing, the method comprising: providing a substrate, comprising an outer conductive layer, a dielectric layer and a target conductive layer, wherein the dielectric layer is arranged between the outer conductive layer and the target conductive layer; forming a copper window on the outer conductive layer to define an opening on the surface of the substrate, wherein the opening has a copper window aperture Dcw, and the opening exposes the dielectric layer at the copper window; Forming a first hole wall section in the dielectric layer, and keeping a residual dielectric layer at the bottom of the hole to cover the target conductive layer, and Performing a laser burning step to remove the residual dielectric layer and form a second hole wall section to expose the target conductive layer at the bottom of the hole, wherein the first hole wall section and the second hole wall section together define the deep blind hole, and the laser burning step comprises: setting a stacked hole configuration area which comprises a plurality of stacked hole striking points, wherein the stacked hole striking points are configured to correspond to a target hole profile of the opening; Setting a stacking rate Rol according to the center distance between two adjacent stacking hole striking points; Applying a first section of laser pulses with n1 times per point to the multiple stacked hole striking points respectively by a first section of laser independent variable group, wherein the first section of laser independent variable group at least comprises a first section of energy E1 and a first section of pulse width PW1, and And respectively applying a second section of laser pulse with the number of n2 times per point to the plurality of stacked hole striking points by using a second section of laser independent variable group, wherein the second section of laser independent variable group at least comprises second section energy E2 and a second section pulse width PW2, and n2 is larger than n1.
  2. 2. The method of claim 1 wherein the step of forming the first hole wall section uses a mechanical drill bit having a drill diameter Dm, wherein the first hole wall section is formed by mechanically blind drilling into the dielectric layer, and wherein the drill diameter Dm is not less than the copper hole diameter Dcw.
  3. 3. The method according to claim 1, wherein the hole overlapping rate Rol is characterized by an overlapping ratio of a center distance Scc of two adjacent hole overlapping striking points relative to an equivalent striking aperture Dp of each hole overlapping striking point, wherein the center distance Scc is smaller than the equivalent striking aperture Dp.
  4. 4. A method according to claim 3, characterized in that the stacking ratio rol= (Dp-Scc)/Dp x 100%.
  5. 5. The method according to claim 4, wherein the porosity Rol is 30% to 60%.
  6. 6. The method of claim 1, wherein the hole stacking configuration region comprises an outer ring layer, a middle ring layer, and a center ring layer, wherein the number of hole stacking hits of the outer ring layer is greater than the number of hole stacking hits of the middle ring layer, and wherein the center ring layer comprises a center hole stacking hit.
  7. 7. The method of claim 6, wherein a total number N of the plurality of stacked hole strikes is less than 50.
  8. 8. The method of claim 7, wherein the number of overlapping hole strikes of the outer ring layer is 8 to 20, the number of overlapping hole strikes of the middle ring layer is 4 to 15, and the number of overlapping hole strikes of the center ring layer is 1 to 3.
  9. 9. The method of claim 1, wherein the first segment pulse width PW1 is greater than the second segment pulse width PW2, the second segment pulse width PW2 is 0.5 microsecond to 2 microseconds, the first segment number n1 per point is 1 to 3, and the second segment number n2 per point is 10 to 40.
  10. 10. The method of claim 1, wherein the ratio of the second stage energy E2 to the first stage energy E1 is defined as a relative energy ratio kE, and the relative energy ratio kE is 0.2 to 0.5.

Description

Method for forming deep blind hole by laser sintering Technical Field The invention relates to a processing technology of a circuit board, in particular to a method for forming a deep blind hole by laser sintering. Background With the development of high-density electronic devices and multi-layer substrate structures, the blind hole designs in circuit boards gradually evolve towards the directions of larger pore diameters and increased pore depths, so as to meet the requirements of high-density wiring, structural integration and electrical connection. Under the trend, when the relative aperture ratio of the hole depth of the blind hole to the hole diameter is increased, a hole shape meeting the design requirement is formed in the dielectric layer, and the hole bottom accurately corresponds to the target conductive layer, so that the method becomes an important subject in process design and parameter configuration. In practical applications, the formation of deep blind holes often involves multiple stages of material removal and hole pattern modification, particularly in the bottom region of the hole, the manner, sequence and configuration of material removal will directly affect hole pattern consistency and overall processing time. When the machining configuration fails to effectively distribute the material removal load, it is prone to significant increases in machining time with increasing hole depth, or uneven structural differences in hole wall and hole bottom topography under repeated action. In addition, the hole-shaped structure of the deep blind hole with large aperture is also one of important consideration for influencing the quality of the subsequent electroplating operation. Disclosure of Invention The invention discloses a method for forming a deep blind hole by laser sintering, which is mainly used for improving the technical problems existing in the prior art. The embodiment of the invention discloses a method for forming a deep blind hole by laser sintering, which comprises the steps of providing a substrate, comprising an outer conductive layer, a dielectric layer and a target conductive layer, wherein the dielectric layer is arranged between the outer conductive layer and the target conductive layer; forming a copper window on the outer conductive layer to define an opening on the surface of the substrate, wherein the opening has a copper window aperture Dcw, and the opening exposes the dielectric layer at the copper window; the method comprises the steps of forming a first hole wall section in a dielectric layer, reserving a residual dielectric layer at the bottom of a hole to cover a target conducting layer, performing a laser burning step to remove the residual dielectric layer and form a second hole wall section to expose the target conducting layer at the bottom of the hole, wherein the first hole wall section and the second hole wall section jointly define the deep blind hole, the laser burning step comprises the steps of setting a hole stacking configuration area which comprises a plurality of hole stacking hitting points, configuring the hole stacking hitting points to correspond to a target hole outline of an opening, setting a hole stacking rate Rol according to the center distance between two adjacent hole stacking hitting points, respectively applying a first section of laser pulses with a number n1 times per point to the hole stacking hitting points by a first section of laser independent variable group, wherein the first section of laser independent variable group at least comprises a first section of energy pulse width E1 and a first section of laser pulse width 1, respectively applying a second section of laser independent variable group with a number n2 of laser pulses with a second section of laser independent variable group to the hole stacking points of a number n2, and applying a second section of laser independent variable group with a number n2 of laser pulses to the second section of laser pulse width E1 respectively to the hole stacking points of the second section of laser variable group. Optionally, the step of forming the first hole wall section uses a mechanical drill with a drilling diameter Dm, and performs mechanical blind drilling in the dielectric layer to form the first hole wall section, where the drilling diameter Dm is not smaller than the copper window hole diameter Dcw. Optionally, the hole overlapping rate Rol is characterized by an overlapping ratio corresponding to a center distance Scc of two adjacent hole overlapping striking points relative to an equivalent striking aperture Dp of each hole overlapping striking point, wherein the center distance Scc is smaller than the equivalent striking aperture Dp. Alternatively, the stacking ratio rol= (Dp-Scc)/dp×100%. Optionally, the stacking porosity Rol is 30% to 60%. Optionally, the hole stacking configuration area comprises an outer ring layer, a middle ring layer and a central ring layer, the number