Method for solving LDI cross-layer alignment
By presetting the alignment PAD and positioning copper skin in the multi-layer PCB, the internal layer deviation problem is solved, the accuracy and efficiency of the graphic window opening of the LDI explosion machine is achieved, and the waste plate rate is reduced.
Patent Information
- Application Number
- CN202411421336.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-12
- Publication Date
- 2024-12-31
AI Technical Summary
During the preparation of multi-layer PCB, the internal layer deviation caused by the compression process is difficult to predict and compensate, resulting in short circuits often occur when the LDI explosion machine is patterned and the board is scrapped.
Before pressing, the alignment PAD is preset in the sub-inner line, and the positioning copper skin is set on the outermost layer. The positioning copper skin and dielectric layer are removed through deep-drilling or deep-milling and laser ablation, exposing the alignment PAD , so that the LDI explosion machine can open the window accurately.
It effectively avoids the short circuit caused by layer deviation, reduces the waste plate rate, and ensures that the window opening accuracy is not affected by the inner layer offset.
Smart Images
Figure CN119233554A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a multi-layer PCB preparation process, and in particular to a method for solving LDI cross-layer alignment. Background Art
[0002] In the prior art, when preparing a multi-layer PCB, the sub-boards with circuits drawn on each layer are stacked and then pressed together to make the dielectric board 10 a whole, and the internal circuits of each layer are distributed in the dielectric board 10 as required. Before the LDI exposure machine makes the graphic window 21, the X-RAY is used to punch the alignment hole 20 at the preset position. The LDI exposure machine is positioned according to the alignment hole 20 and punches the graphic window 21 at the specified position. The ideal result is as follows Figure 1 As shown, there is no layer deviation in the inner layer circuits of the board, so the alignment holes 20 are in the correct position relative to each layer, and therefore the graphic openings 21 printed by the LDI exposure machine are also correct.
[0003] However, in actual work, idealized results are more likely to appear as extreme cases. In more actual situations, the inner layer has layer deviation due to intermediate processes such as lamination. Moreover, these layer deviation phenomena cannot be predicted and are extremely difficult to compensate for in the later stage. When the sub-inner layer line 11 is deviated to the left, the graphic window 21 will penetrate the line and cause the line to short-circuit. The short-circuit position is as follows: Figure 1 On the contrary, when the sub-inner layer line 11 is deviated to the right, the patterned opening 21 will also penetrate the line and cause the line to short-circuit. Figure 1 As shown in B.
[0004] As long as a short circuit occurs, the PCB board will become a waste board, so layer deviation control has always been a technical pain point in the industry. Summary of the invention
[0005] The present invention aims to provide a method for solving LDI cross-layer alignment, so as to solve the problems existing in the above-mentioned prior art.
[0006] The method for solving the cross-layer alignment of LDI described in the present invention is to preset the alignment PAD in the second inner layer circuit before the sub-boards are pressed together; and to set a positioning copper foil in the outermost layer circuit to indicate the position of the alignment PAD;
[0007] Press the sub-boards together into a whole;
[0008] When it is necessary to perform graphic windowing, firstly remove the material at the position corresponding to the positioning copper foil until the alignment PAD is exposed; then use the LDI exposure machine to perform windowing according to the alignment PAD.
[0009] The specific steps of removing material at the position corresponding to the positioning copper sheet are: removing the positioning copper sheet at the position of the alignment PAD by controlled depth drilling or controlled depth milling; removing the dielectric layer at the position of the alignment PAD by laser ablation until the alignment PAD is exposed.
[0010] The method for solving the cross-layer alignment of LDI described in the present invention has the advantage that, since the alignment PAD is synchronously offset with the effective part of the sub-inner layer circuit, no matter in which direction the sub-inner layer circuit is offset or what the offset value is, the window can be accurately opened according to the alignment PAD without breaking down the corresponding circuit. The short circuit phenomenon caused by the layer deviation problem is completely avoided, and the scrap rate is effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 It is a schematic diagram of a method for making graphical window opening in the prior art.
[0012] Figure 2 It is a schematic diagram of the effect of inner layer misalignment when making graphical window opening in the prior art.
[0013] Figure 3 It is a schematic diagram of the in-board structure of the method described in the present invention.
[0014] Figure 4 It is an intermediate flow diagram of the method described in the present invention.
[0015] Figure 5 It is a schematic diagram of the window opening effect of the method described in the present invention when the inner layer is in an ideal state.
[0016] Figure 6 It is a schematic diagram of the window opening effect when the inner layer is in a dislocated state according to the method of the present invention.
[0017] Reference numerals:
[0018] 10- dielectric board, 11- secondary inner layer circuit, 12- alignment PAD;
[0019] 20-alignment hole, 21-graphic window. DETAILED DESCRIPTION
[0020] The method for solving the cross-layer alignment of LDI described in the present invention is to preset the alignment PAD 12 in the second inner layer circuit 11 before the sub-boards are pressed together. A positioning copper foil for indicating the position of the alignment PAD 12 is set in the outermost layer circuit. The sub-boards are pressed together as a whole, such as Figure 3 shown.
[0021] When it is necessary to open the graphic window 21, the positioning copper foil at the position of the alignment PAD 12 is removed by controlled depth drilling or controlled depth milling. The dielectric layer at the position of the alignment PAD 12 is removed by laser ablation until the alignment PAD 12 is exposed. Figure 4 Then, the LDI exposure machine is used to perform window opening according to the alignment PAD 12 .
[0022] If there is no layer deviation in the inner layer, that is, it is in an ideal state, the window opening effect is as follows: Figure 5 shown.
[0023] If the inner layer deviates to the left or right, that is, it is in a non-ideal layer deviation state, since the alignment PAD 12 and the effective part of the sub-inner layer line 11 are synchronously offset, no matter in which direction the sub-inner layer line 11 deviates, and no matter how much the offset value is, the window can be accurately opened according to the alignment PAD 12 without breaking down the corresponding line. Figure 6 shown.
[0024] For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all of these changes and deformations should fall within the protection scope of the claims of the present invention.
Claims
1. A method for solving LDI cross-layer alignment, characterized in that: Before the sub-boards are pressed together, the alignment PAD (12) is preset in the second inner layer circuit (11); and a positioning copper foil for indicating the position of the alignment PAD (12) is arranged in the outermost layer circuit; Press the sub-boards together into a whole; When it is necessary to print a graphic window (21), firstly remove the material at the position corresponding to the positioning copper foil until the alignment PAD (12) is exposed; then use the LDI exposure machine to perform the window opening work according to the alignment PAD (12).
2. According to the method for solving LDI cross-layer alignment according to claim 1, it is characterized in that: The specific steps of removing material at the position corresponding to the positioning copper sheet are: removing the positioning copper sheet at the position of the positioning PAD (12) by using a controlled depth drilling or controlled depth milling method; and removing the dielectric layer at the position of the positioning PAD (12) by using a laser ablation method until the positioning PAD (12) is exposed.