WO2022082920A1

WO2022082920A1 - Circuit board drilling method

Info

Publication number: WO2022082920A1
Application number: PCT/CN2020/130811
Authority: WO
Inventors: 韩轮成; 袁绩; 常远
Original assignee: 苏州维嘉科技股份有限公司
Priority date: 2020-04-10
Filing date: 2020-11-23
Publication date: 2022-04-28
Also published as: CN113518505B; CN113518505A

Abstract

A circuit board drilling method, comprising: arranging between a drilling-through layer (3) and a non-drilling-through layer (1) of a workpiece a conductive layer (2) having the same thickness; placing the workpiece on a pad (4); using a first drill bit to drill at a position on the top surface of the workpiece which corresponds to a back drill hole to be processed (5); after the first drill bit contacts a surface copper layer of the workpiece, recording the position of the top surface of the workpiece in the height direction, and stopping drilling when the first drill bit drills through the surface copper layer; using a second drill bit to drill at a position where the first drill bit stops drilling; when the second drill bit contacts the top surface of the conductive layer, recording the position of the top surface of the conductive layer in the height direction, and stopping drilling after the second drill bit drills through the conductive layer; and if the non-drilling-through layer of the workpiece is located above the drilling-through layer, turning over the workpiece, placing the workpiece on the pad, and using a back drill bit to drill a back drill hole on the drilling-through layer.

Description

Circuit board drilling method

This application claims the priority of a Chinese patent application with an application date of October 22, 2020 and an application number of 202011139629.6, the entire contents of which are incorporated herein by reference.

technical field

The present application relates to the technical field of circuit board processing, for example, to a method for drilling and processing circuit boards.

Background technique

In the design of a multi-layer printed circuit board (Printed Circuit Board, PCB board), via holes are usually used to transmit signals. A part of the via hole is usually used to transmit signals, and the other part is not used for any connection and transmission, and this part will cause reflection, scattering, delay, etc. of high-speed signal transmission, resulting in signal distortion. In order to solve this problem, the redundant non-conductive part in the via hole is usually drilled by controlling the drilling depth to improve the integrity of the signal transmission. This process is mostly used from the circuit when the drilling depth is controlled. The back side of the board is processed, so it is called back drilling.

Multilayer circuit boards are usually made by pressing multiple layers of resin and copper foil. Due to the error in the lamination process, the thickness of the circuit board is different, the thickness of different circuit boards is different, the thickness of the same circuit board is also different, and the height of each layer is also fluctuating and changing greatly. However, in the existing circuit board drilling processing method, the fluctuation of each layer is usually ignored, and the back-drilling is uniformly performed according to a fixed preset depth, which results in that the layers that need to be drilled are not drilled or the layers that do not need to be drilled are not drilled. The occurrence of phenomena such as layer drilling through, greatly reduces the back-drilling efficiency and product yield.

SUMMARY OF THE INVENTION

The present application provides a method for drilling a circuit board, which can overcome the error of the drilling depth caused by the fluctuation of each layer of the circuit board, realize the precise control of the drilling depth during back drilling, improve the product yield, reduce scrap, and at the same time Improve backdrilling efficiency and backdrilling quality.

An embodiment provides a method for drilling a circuit board, including:

Step 1: A conduction layer with the same thickness is set between the layer to be drilled through and the non-drillable layer of the workpiece, and the same thickness is denoted as H ₁ ; wherein the non-drillable layer is far from the conduction layer One side of the layer is provided with a surface copper layer, and the side of the layer to be drilled away from the conducting layer is provided with a surface copper layer;

Step 2: Place the workpiece on the backing plate, use a first drill to drill down on the top surface of the workpiece at a position corresponding to the back hole to be machined, and the first drill contacts the workpiece. After the surface copper layer, record the position of the top surface of the workpiece in the height direction and mark it as H ₂ , and stop drilling after the first drill drill penetrates the surface copper layer;

Step 3: Use a second drill to drill up and down at the position where the first drill stops drilling. The diameter of the second drill is smaller than the diameter of the first drill. When the top surface of the conductive layer is in contact, record the position of the top surface of the conductive layer in the height direction and mark it as H ₃ , and stop drilling after the second drill drill penetrates the conductive layer;

Step 5: Under the condition that the non-drillable layer of the workpiece placed on the backing plate is above the to-be-drilled layer, calculate the distance between _H2 and _H3 , and denote it as L ₁ , L ₁ =|H ₂ -H ₃ |; turn the workpiece over and place it on the backing plate to keep the layer to be drilled away from the backing plate; use a back-drilling drill to drill through the backing plate Drill holes on the layer at the positions corresponding to the back-drilled holes to be processed, so as to drill out the back-drilled holes; wherein, the drilling depth of the back-drill needles is Ha=H ₀ -L ₁ -H ₁ -h, wherein , H ₀ is the distance between the position of the top surface of the workpiece detected by the back drill bit in the height direction and the backing plate when the layer to be drilled is placed away from the backing plate, and h is the machining allowance.

Description of drawings

1 is a flowchart of a circuit board drilling method provided by an embodiment of the present application;

2 is a schematic diagram of a circuit board drilling processing method under the condition that the non-drillable layer of the workpiece placed on the backing plate provided by the embodiment of the present application is above the layer to be drilled through;

3 is a schematic diagram of a method for drilling a circuit board when the non-drillable layer of the workpiece placed on the backing plate provided by the embodiment of the present application is below the layer to be drilled through.

In the picture:

1- Do not drill through the layer;

2-Conduction layer;

3- need to drill through the layer;

4-pad;

5- Back drilling.

Detailed ways

In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "height", "horizontal", "inner", "outer", etc. indicate The orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation or be constructed in a specific orientation. and operation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only or to distinguish between different structures or components, and should not be construed to indicate or imply relative importance. Therein, the terms "first position" and "second position" are two different positions.

In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection Connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood in specific situations.

As shown in FIG. 1 and FIG. 2 , this embodiment provides a method for drilling a circuit board, including:

S10: A conductive layer 2 with the same thickness is arranged between the layer to be drilled 3 and the non-drillable layer 1 of the workpiece, and the same thickness of the conductive layer 2 is denoted as H ₁ , wherein the non-drillable layer 1 is far away from A surface copper layer is provided on one side of the conducting layer 2 , and a surface copper layer is provided on the side that needs to be drilled through the layer 3 away from the conducting layer 2 .

S20: Place the workpiece on the backing plate 4, use the first drill to drill down on the top surface of the workpiece at the position corresponding to the back hole 5 to be processed, and record the workpiece after the first drill contacts the surface copper layer of the workpiece The position of the top surface in the height direction is marked as H ₂ , and the first drill needle drills through the surface copper layer and stops drilling;

S30: Use a second drill to drill up and down at the position where the first drill stopped drilling down. The diameter of the second drill is smaller than the diameter of the first drill. When the second drill is in contact with the top surface of the conduction layer 2, Record the position of the top surface of the conduction layer 2 in the height direction and mark it as H ₃ , and stop drilling down after the second drill drills through the conduction layer 2;

S50: In the case where the non-drillable layer 1 of the workpiece placed on the backing plate 4 is above the layer 3 to be drilled through, calculate the distance between H ₂ and H ₃ and denote it as L ₁ , L ₁ =|H ₂ -H ₃ |; Turn the workpiece over and place it on the backing plate 4 so that the layer 3 to be drilled is far away from the backing plate 4, as shown in Figure 3, use a back-drilling drill on the layer 3 to be drilled to correspond to the The position of the processed back hole 5 is drilled to drill the back hole 5, and the drilling depth of the back drill needle is Ha=H ₀ -L ₁ -H ₁ -h, where H ₀ is the required drilling of the workpiece When the penetration layer 3 is placed away from the backing plate 4, the distance between the top surface of the workpiece detected by the back-drilling needle in the height direction and the backing plate 4, h is the machining allowance, that is, the hole that needs to be drilled under the conduction layer 2 distance.

In the circuit board drilling processing method in this embodiment, the drilling depth during back drilling can be controlled according to the actual undulation at the position where the back drilling is required, rather than a fixed preset depth or some adjacent positions. The reference point is used to control the drilling depth of the back drilling. Therefore, the circuit board drilling processing method provided by the present application can overcome the drilling depth error caused by the fluctuation of each layer of the circuit board, and realize the accurate drilling depth during back drilling. It is beneficial to improve product yield, reduce scrap, avoid secondary back-drilling of workpieces, and improve back-drilling efficiency and back-drilling quality.

Exemplarily, in order to facilitate back-drilling processing of the workpiece, S30 further includes S40: in the case that the non-drillable layer 1 of the workpiece placed on the backing plate 4 is below the layer 3 to be drilled, a third drill is used. The needle drills up and down at the position where the second drill needle stops drilling, and the diameter of the third drill needle is smaller than that of the second drill needle. When the third drill needle contacts the surface copper layer of the non-drillable layer 1, record the position Position H ₄ in the height direction; calculate the distance between H ₃ and H ₄ and denote it as L ₂ , L ₂ =|H ₃ -H ₄ | The position of the back hole 5 to be processed is drilled to drill the back hole 5, and the drilling depth of the back drill needle is Ha=H ₀ -L ₂ -H ₅ -h, wherein H ₅ is not drilled through The thickness of the surface copper layer of layer 1.

In this embodiment, the position H ₂ in the height direction of the surface to be drilled through the layer 3 is detected by means of physical contact, but it is not limited to this method, and other methods for detecting H ₂ are acceptable. In addition, in this embodiment, the position H ₃ of the top surface of the conduction layer 2 in the height direction is detected by using a drilling method, but it is not limited to this method, and other methods for detecting H ₃ may be used.

In this embodiment, when back _- drilling multiple workpieces, it also includes repeatedly executing S20, S30, S40 and S50, encoding each workpiece, and storing L1 and L2 _of each workpiece corresponding to the encoding until The L ₁ and L ₂ of all workpieces are stored corresponding to the codes. When back-drilling is required for multiple workpieces, in order to avoid the confusion of detected data among multiple workpieces, in this embodiment, each workpiece is coded, and L ₁ and L ₂ of each workpiece are combined with the coding Store in one-to-one correspondence.

When back-drilling multiple workpieces, the method further includes: retrieving L ₁ or L ₂ corresponding to the codes of the workpieces to be back-drilled, so as to determine the drilling depth Ha of the back-drilling drill for the workpieces to be back-drilled. When back-drilling a certain workpiece, it is necessary to retrieve the previously stored L ₁ or L ₂ of the workpiece, and then determine the drilling depth Ha of the workpiece according to L ₁ or L ₂ to back-drill the workpiece. Drill holes 5.

The method also includes plating copper in the through hole drilled by the third drill. The third drill needle passes through layer 3 to be drilled and conductive layer 2 and then drills through non-drillable layer 1. After copper plating, the through holes of layer 3, conductive layer 2 and non-drillable layer 1 are all copper , and then remove the copper in the vias that need to be drilled through layer 3 to prevent signal distortion.

Optionally, in S30 , the diameter of the second drill pin is smaller than the diameter of the back hole 5 , so that the copper plating in the through hole is removed through the back hole 5 .

Optionally, in S30 , when a current loop is formed between the conductive layer 2 , the second drill needle and the drilling machine, and the trigger signal disappears, it is determined that the second drill needle is in contact with the top surface of the conductive layer 2 .

Optionally, in S40 and S50, the diameter of the back drill needle is equal to the diameter of the back drill hole 5 .

Optionally, in S10, the conduction layer 2 is a copper layer, and the conduction layer 2, the surface copper layer of the layer 3 to be drilled and the surface copper layer of the non-drillable layer 1 are all formed by an inner layer exposure process.

The beneficial effects of this application are:

In the circuit board drilling method provided by the present application, a conductive layer 2 with the same thickness is arranged between the layer to be drilled 3 and the layer 1 that cannot be drilled through, and a first drill pin is used to contact the surface copper layer of the workpiece , the actual height H ₂ of the surface copper layer of the workpiece at this position can be detected, and the actual height H ₃ of the conductive layer 2 at this position can be detected by using the second drill to contact the top surface of the conduction layer 2 , and then control the drilling depth during back drilling according to H ₂ and H ₃ , that is, control the drilling depth during back drilling according to the actual high and low fluctuations at the position where the back drilling is required, rather than according to a fixed preset depth or at Some adjacent positions are taken as reference points to control the drilling depth of the back drilling. Therefore, the circuit board drilling processing method provided by the present application can overcome the drilling depth error caused by the fluctuation of each layer of the circuit board, and realize the back drilling. The precise control of the drilling depth at the same time is beneficial to improve the product yield, reduce scrap, avoid secondary back-drilling on the workpiece, and improve back-drilling efficiency and back-drilling quality.

Claims

A method for drilling a circuit board, comprising:

Step 1 (S10): A conductive layer (2) with the same thickness is provided between the layer to be drilled through (3) and the layer (1) that cannot be drilled through, and the same thickness is denoted as H 1 ; wherein , the non-drillable layer (1) is provided with a surface copper layer on the side away from the conductive layer (2), and the drill-through layer (3) is provided on the side away from the conductive layer (2) There is a surface copper layer;

Step 2 (S20): place the workpiece on the backing plate (4), use a first drill to drill down on the top surface of the workpiece at a position corresponding to the back hole (5) to be processed, and the After the first drill pin contacts the surface copper layer of the workpiece, record the position of the top surface of the workpiece in the height direction and mark it as H 2 , and stop drilling down after the first drill pin drills through the surface copper layer ;

Step 3 (S30): Use a second drill to drill up and down at the position where the first drill stops drilling down. The diameter of the second drill is smaller than the diameter of the first drill. When the needle is in contact with the top surface of the conductive layer (2), the position of the top surface of the conductive layer (2) in the height direction is recorded and marked as H3 , and the second drill needle drills through the Stop drilling down after the conduction layer (2);

Step 5 (S50): In the case that the non-drillable layer (1) of the workpiece placed on the backing plate (4) is above the to-be-drilled layer (3), calculate H 2 The distance between H 3 and L 1 is denoted as L 1 , L 1 =|H 2 -H 3 |; the workpiece is turned over and placed on the backing plate (4) to make the layer (3) to be drilled through ) away from the backing plate (4); use a back drill needle to drill holes on the layer (3) to be drilled at a position corresponding to the back drill hole (5) to be processed to drill out the back drill hole ( 5); wherein, the drilling depth of the back-drilling needle is Ha=H 0 -L 1 -H 1 -h, wherein H 0 is the layer (3) to be drilled and placed away from the backing plate (4) is the distance between the position of the top surface of the workpiece detected by the back-drilling needle in the height direction and the backing plate (4), and h is the machining allowance.
The method for drilling a circuit board according to claim 1, wherein after step 3 (S30), it further comprises:

Step 4 (S40): when the non-drillable layer (1) of the workpiece placed on the backing plate (4) is below the layer to be drilled (3), use a third drill Drill up and down at the position where the second drill needle stops drilling, the diameter of the third drill needle is smaller than the diameter of the second drill needle, when the third drill needle and the non-drillable layer (1) When the surface copper layer is in contact, record the position H 4 of the position in the height direction; calculate the distance between H 3 and H 4 , and record it as L 2 , L 2 =|H 3 -H 4 |; The back-drilling needle drills a hole on the layer (3) to be drilled at a position corresponding to the back-drilled hole (5) to be processed, so as to drill out the back-drilled hole (5); wherein, the back-drilled drill The drilling depth of the needle is Ha = H 0 -L 2 -H 5 -h, where H 5 is the thickness of the surface copper layer of the non-drillable layer ( 1 ).
The method for drilling a circuit board according to claim 2, wherein when back-drilling a plurality of the workpieces, it further comprises repeatedly performing steps 2 (S20), 3 (S30), 4 (S40) and steps 5 (S50), and code each of the workpieces, store L1 and L2 of each of the workpieces corresponding to the code, until the L1 and L2 of all the workpieces are stored corresponding to the code Finish.
The circuit board drilling method according to claim 3, further comprising: when back-drilling a plurality of the workpieces, fetching L 1 or L 2 corresponding to the code of the workpiece to be back-drilled to determine the The drilling depth Ha of the back drill for the workpiece to be back drilled.
The method for drilling a circuit board according to claim 2, further comprising plating copper in the through hole drilled by the third drill.
The circuit board drilling method according to claim 1, wherein the diameter of the second drill pin is smaller than the diameter of the back hole (5).
The method for drilling a circuit board according to claim 1, wherein, in step 3 (S30), when a current loop is formed between the conductive layer (2), the second drill needle and the drilling machine, When the trigger signal disappears, it is determined that the second drill needle is in contact with the top surface of the conduction layer (2).
The circuit board drilling method according to claim 1, wherein the diameter of the back drill needle is equal to the diameter of the back drill hole (5).
The method for drilling a circuit board according to claim 1, wherein the conducting layer (2) is a copper layer, the copper layer, the surface copper layer of the layer to be drilled (3) and the inoperable layer (3) The surface copper layers of the drill-through layer (1) are all formed by an inner layer exposure process.