CN115515336A - Back drilling method for PCB (printed circuit board) - Google Patents

Back drilling method for PCB (printed circuit board) Download PDF

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Publication number
CN115515336A
CN115515336A CN202211049882.1A CN202211049882A CN115515336A CN 115515336 A CN115515336 A CN 115515336A CN 202211049882 A CN202211049882 A CN 202211049882A CN 115515336 A CN115515336 A CN 115515336A
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CN
China
Prior art keywords
drilling
drill
length
hole
water washing
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202211049882.1A
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Chinese (zh)
Inventor
李会霞
陈涛
赵启祥
李波
张志洲
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Victory Giant Technology Huizhou Co Ltd
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Victory Giant Technology Huizhou Co Ltd
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Priority to CN202211049882.1A priority Critical patent/CN115515336A/en
Publication of CN115515336A publication Critical patent/CN115515336A/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
    • H05K3/42—Plated through-holes or plated via connections
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/0011—Working of insulating substrates or insulating layers
    • H05K3/0044—Mechanical working of the substrate, e.g. drilling or punching
    • H05K3/0047—Drilling of holes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/0011—Working of insulating substrates or insulating layers
    • H05K3/0055—After-treatment, e.g. cleaning or desmearing of holes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/0085—Apparatus for treatments of printed circuits with liquids not provided for in groups H05K3/02 - H05K3/46; conveyors and holding means therefor
    • H05K3/0088—Apparatus for treatments of printed circuits with liquids not provided for in groups H05K3/02 - H05K3/46; conveyors and holding means therefor for treatment of holes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/0094—Filling or covering plated through-holes or blind plated vias, e.g. for masking or for mechanical reinforcement
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/09—Shape and layout
    • H05K2201/09209—Shape and layout details of conductors
    • H05K2201/095—Conductive through-holes or vias
    • H05K2201/0959—Plated through-holes or plated blind vias filled with insulating material
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/07—Treatments involving liquids, e.g. plating, rinsing
    • H05K2203/0736—Methods for applying liquids, e.g. spraying
    • H05K2203/074—Features related to the fluid pressure
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/07—Treatments involving liquids, e.g. plating, rinsing
    • H05K2203/0756—Uses of liquids, e.g. rinsing, coating, dissolving
    • H05K2203/0766—Rinsing, e.g. after cleaning or polishing a conductive pattern

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)

Abstract

The invention discloses a PCB back drilling method, which sequentially comprises the following steps: the method comprises the following steps of a former step, drilling, copper deposition, plate electroplating, back drilling, water washing, resin hole plugging and a later step; if the length of the back drill is less than or equal to 0.3mm, drilling holes at one time; if the length of the back drill is 0.31-0.5 mm, the back drill is divided into 2 sections for drilling; if the length of the back drill is 0.51-1.0 mm, the back drill is divided into 3 sections for drilling; if the length of the back drill is 1.01-1.5 mm, the back drill is divided into 5 sections for drilling; if the length of the back drill is 1.51-2.0 mm, the back drill is divided into 6 sections for drilling; if the length of the back drill is more than or equal to 2.1mm, 7 sections are drilled; washing with water: placing the PCB with the back drilling surface facing downwards, and sequentially performing hole plug removal, pressurized water washing I, ultrasonic water washing, HF water washing, high-pressure water washing and pressurized water washing II; an aluminum sheet is adopted for resin hole plugging, and the aluminum sheet comprises a resin layer, a wood fiber layer and an aluminum layer which are sequentially connected; when the resin is filled into the hole, the side of the resin layer is placed on the PCB. The invention shortens the flow of manufacturing the back drilling hole, reduces the cost and improves the quality of the back drilling hole.

Description

Back drilling method for PCB (printed circuit board)
Technical Field
The invention relates to the field of PCBs, in particular to a PCB back drilling method.
Background
With the continuous promotion and development of the information-based industry, the speed of digital signal transmission is faster and faster, the frequency is higher and higher, the requirement of the high-frequency circuit cannot be met by the PCB with the traditional design, and the integrity transmission of signals becomes an important technology which is more and more critical. When the frequency of the circuit signal is increased to a certain height, a useless hole copper part exists in a PTH hole on the PCB, the redundant hole copper is equivalent to an antenna, signal radiation can be generated, interference is caused to other surrounding signals, and the normal work of a circuit system can be seriously influenced. The main factors affecting the signal integrity of the signal system include design, board material, etc., and the via hole also has a large influence on the signal integrity. In the manufactured circuit board, a common multilayer circuit board is provided with a discontinuous signal path at a via hole, so that impedance discontinuity is easily caused when a signal passes through, and the problem of influencing the integrity of the signal is caused.
The conventional back drilling process that adopts drills away unnecessary via hole copper deposit layer, and the back drilling is the more special one in the depth control bores, and the effect of back drilling is to bore away the through-hole section that does not play any connection or transmission effect, avoids causing reflection, scattering or delay etc. of high-speed signal transmission, leads to signal distortion. The existing back drilling process is as follows in sequence: the method comprises the following steps of a former process, drilling, copper deposition, board electricity, pattern electrotinning, back drilling, flash etching or etching, film stripping, tin stripping and a later process, and is long in flow, high in cost and easy to cause plate surface scratching by matching with a large number of manual carrying actions.
Disclosure of Invention
The invention provides a back drilling method for a PCB (printed circuit board) in order to solve the problems of long process and poor quality of back drilling holes of the conventional back drilling.
A PCB back drilling method sequentially comprises the following steps: the method comprises the following steps of a former procedure, drilling, copper deposition, plate electrification, back drilling, water washing, resin hole plugging and a later procedure;
the back drilling:
if the length of the back drill is less than or equal to 0.3mm, drilling at one time;
if the length of the back drill is 0.31-0.5 mm, the back drill is divided into 2 sections for drilling;
if the length of the back drill is 0.51-1.0 mm, the back drill is divided into 3 sections for drilling;
if the length of the back drill is 1.01-1.5 mm, the back drill is divided into 5 sections for drilling;
if the length of the back drill is 1.51-2.0 mm, the back drill is divided into 6 sections for drilling;
if the length of the back drill is more than or equal to 2.1mm, 7 sections are drilled;
and (3) washing: placing the PCB with the back drilling surface facing downwards, and sequentially performing hole plug removal, pressurized water washing I, ultrasonic water washing, HF water washing, high-pressure water washing and pressurized water washing II;
plugging holes with the resin: an aluminum sheet is adopted for resin hole plugging, and the aluminum sheet comprises a resin layer, a wood fiber layer and an aluminum layer which are sequentially connected; when the resin is filled into the hole, the side of the resin layer is placed on the PCB. The back drilling hole manufactured by the method has high efficiency, does not need etching and has better quality.
Optionally, the thickness of the aluminum sheet is 0.46mm, and the error is +/-10%.
Optionally, the thickness of the aluminum layer is 0.12 to 0.14mm.
Optionally, the back drill:
if the length of the back drill is less than or equal to 0.3mm, the feed speed is 1.8m/min, the withdrawal speed is 26m/min, and the rotating speed is 120krpm;
if the length of the back drill is 0.31-0.5 mm, the feed speed is 1.7m/min, the withdrawal speed is 25m/min, and the rotating speed is 115krpm;
if the length of the back drill is 0.51-1.0 mm, the feed speed is 1.6m/min, the withdrawal speed is 24m/min, and the rotating speed is 110krpm;
if the length of the back drill is 1.01-1.5 mm, the feed speed is 1.5m/min, the withdrawal speed is 23m/min, and the rotating speed is 105krpm;
if the length of the back drill is 1.51-2.0 mm, the feed speed is 1.4m/min, the withdrawal speed is 22m/min, and the rotating speed is 100krpm;
if the length of the back drill is more than or equal to 2.1mm, the feed speed is 1.2m/min, the withdrawal speed is 20m/min, and the rotating speed is 90krpm. The back drilling effect is good, and the quality of the back drilling hole is good.
Optionally, the back drill:
if the length of the back drill is less than or equal to 0.3mm, the hole limit of the adopted drill bit is 500;
if the length of the back drill is 0.31-0.5 mm, the hole limit of the adopted drill bit is 500;
if the length of the back drill is 0.51-1.0 mm, the hole limit of the adopted drill bit is 500;
if the length of the back drill is 1.01-1.5 mm, the hole limit of the adopted drill bit is 200;
if the length of the back drill is 1.51-2.0 mm, the hole limit of the adopted drill bit is 150;
if the back drill has a length of 2.1mm or more, the hole limit of the drill bit is 100.
Optionally, the pressure adopted by the pore-removing plug is 0.55-0.75 Mpa, and the pressure adopted by the pressurized water washing is 1.5-2.5 kg/cm 2 The pressure adopted by ultrasonic water washing is 90bar, the error is +/-10 percent, and the pressure adopted by HF water washing is 1.5-2.5 kg/cm 2 The pressure adopted by the high-pressure water washing is 115-125 bar, and the pressure adopted by the second pressurized water washing is 1.5-2.5 kg/cm 2 . Ensuring the quality of the back drilled hole.
Optionally, the back drill adopts a drill with a blade length of 5.0mm. Ensuring the quality of the back drilled hole.
Optionally, the back drill adopts ST drill. Ensuring the quality of the back drilled hole.
Optionally, the back drill adopts dust collection equipment to collect dust while drilling, and the used dust collection pressure is 17-20 KPa. Ensuring the quality of the back drilled hole.
Optionally, after the water washing, the back drilling hole of the PCB board is tested. And testing whether the back drilling hole meets the requirements or not, and avoiding the outflow of defective products.
Compared with the prior art, the invention has the beneficial effects that: the PCB back drilling method provided by the invention does not need etching of the back drilling hole, shortens the process of manufacturing the back drilling hole and reduces the cost; according to the difference of the back drilling depth, different drilling modes and various water washing modes are adopted, so that the quality of the back drilling hole is improved; the aluminum sheet of resin consent is the three layer construction of resin layer, wood fibre layer and aluminium lamination, and the resin consent is effectual, is favorable to improving the quality of PCB board.
Detailed Description
In order to explain the technical solution of the present invention in detail, the technical solution of the embodiment of the present invention will be clearly and completely described below.
Example 1:
the embodiment provides a back drilling method for a PCB, which sequentially comprises the following steps: the method comprises the steps of pre-processing, drilling, copper deposition, plate electric, back drilling, water washing, resin hole plugging and post-processing.
The former procedure comprises cutting the PCB.
Drilling, copper deposition and plate electric: and (4) manufacturing to form a PTH hole, and thickening the thickness of a copper layer on the surface of the PCB.
Back drilling: back drilling the PTH hole by using a back drill, and drilling the hole at one time if the length of the back drill is less than or equal to 0.3 mm; if the length of the back drill is 0.31-0.5 mm, the back drill is divided into 2 sections for drilling; if the length of the back drill is 0.51-1.0 mm, the back drill is divided into 3 sections for drilling; if the length of the back drill is 1.01-1.5 mm, the back drill is divided into 5 sections for drilling; if the length of the back drill is 1.51-2.0 mm, the back drill is divided into 6 sections for drilling; if the back drill is longer than or equal to 2.1mm, the back drill is divided into 7 sections for drilling.
According to different depths of the back drill, the back drill hole is drilled in a segmented drilling mode, the accuracy of the back drill hole is improved, and if the back drill hole needs to be drilled in multiple segments, the length of each segment can be consistent.
Washing with water: placing the PCB with the back drilling surface facing downwards, and sequentially performing hole plug removal, first pressurized water washing, ultrasonic water washing, HF water washing, high-pressure water washing and second pressurized water washing.
And (3) washing after back drilling to remove redundant copper scraps or residual copper wires on the back drilling hole and ensure the quality of the back drilling hole, wherein two washing modes of pressurized water washing I, ultrasonic water washing, HF water washing, high-pressure water washing and pressurized water washing are adopted to ensure the washing effect.
Resin hole plugging: an aluminum sheet is adopted for resin hole plugging, and the aluminum sheet comprises a resin layer, a wood fiber layer and an aluminum layer which are sequentially connected; when the resin is filled into the hole, the side of the resin layer is placed on the PCB.
This aluminum sheet adopts the three layer construction of resin layer, wood fiber layer and aluminium lamination, and the roughness is good, is difficult to corrugate and warp, conveniently tests the hole, and the thickness of resin layer is 0.02 ~ 0.03mm, and the resin layer mainly plays fixed drill point, prevents its effect of skidding off normal, and the resin layer mainly plays the effect that the clearance drill point bore dirt with wood fiber layer.
The invention does not need tin plating, etching and tin stripping, shortens the process, improves the production efficiency, and has proved that the cost of the back drill can be reduced by 60 percent compared with the prior process and the quality of the manufactured back drill hole is good.
The aluminum sheet had a thickness of 0.46mm with a tolerance of + -10%. The thickness of the aluminum layer is 0.12-0.14 mm. When the back drilling hole made by the back drill is used for resin hole plugging, the surface of the resin layer of the aluminum sheet is placed on the PCB, namely the aluminum layer of the aluminum sheet is arranged above the resin layer and the wood fiber layer.
Back drilling: if the length of the back drill is less than or equal to 0.3mm, the hole limit of the adopted drill bit is 500; if the length of the back drill is 0.31-0.5 mm, the hole limit of the adopted drill bit is 500; if the length of the back drill is 0.51-1.0 mm, the hole limit of the adopted drill bit is 500; if the length of the back drill is 1.01-1.5 mm, the hole limit of the adopted drill bit is 200; if the length of the back drill is 1.51-2.0 mm, the hole limit of the adopted drill bit is 150; if the length of the back drill is more than or equal to 2.1mm, the hole limit of the adopted drill bit is 100. The hole limit is the service life of the drill bit adopted by the back drill, and the drill bit needs to be replaced when the service life is prolonged, so that the hole wall quality after drilling is improved, and a copper layer needing to be removed in the hole can be completely cut off.
Back drilling: the edge length of the drill bit is 5.0mm, the drill bit is an ST drill bit, threads on the surface of the drill bit are dense, and the drill bit is manufactured by welding.
Back drilling: and (3) dust collection equipment is adopted to collect dust while drilling, and the used dust collection pressure is 17-20 KPa. The conventional dust suction pressure is 10-12KPa, the dust suction pressure of the dust suction device is increased, dust, copper scraps and other scraps on a back drilling hole can be quickly cleaned, and the situation that the holes are blocked by the scraps is avoided.
After washing, the back drilling holes of the PCB are tested, and the quality of the back drilling holes is better as shown in the following table.
Figure RE-GDA0003947532980000051
Example 2:
the embodiment provides a PCB back drilling method, which sequentially comprises the following steps: the method comprises the following steps of pre-processing, drilling, copper deposition, plate electric, back drilling, water washing, resin hole plugging and post-processing.
The former procedure comprises cutting the PCB.
Drilling, copper deposition and plate electric: and (4) manufacturing to form a PTH hole, and thickening the thickness of a copper layer on the surface of the PCB.
Back drilling: back drilling the PTH hole by using a back drill, and drilling the hole at one time if the length of the back drill is less than or equal to 0.3 mm; if the length of the back drill is 0.31-0.5 mm, the back drill is divided into 2 sections for drilling; if the length of the back drill is 0.51-1.0 mm, the back drill is divided into 3 sections for drilling; if the length of the back drill is 1.01-1.5 mm, the back drill is divided into 5 sections for drilling; if the length of the back drill is 1.51-2.0 mm, the back drill is divided into 6 sections for drilling; if the length of the back drill is more than or equal to 2.1mm, the back drill is divided into 7 sections for drilling. According to the different degree of depth of back drilling, adopt the mode of segmentation drilling to bore out the back drilling, improve the precision of back drilling, if need divide into the multistage and bore holes, the length of every section can be unanimous.
Washing with water: placing the PCB with the back drilling surface facing downwards, and sequentially performing hole plug removal, first pressurized water washing, ultrasonic water washing, HF water washing, high-pressure water washing and second pressurized water washing. And (3) washing after back drilling to remove redundant copper scraps or residual copper wires on the back drilling hole and ensure the quality of the back drilling hole, wherein two washing modes of pressurized water washing I, ultrasonic water washing, HF water washing, high-pressure water washing and pressurized water washing are adopted to ensure the washing effect.
Resin hole plugging: an aluminum sheet is adopted for resin hole plugging, and the aluminum sheet comprises a resin layer, a wood fiber layer and an aluminum layer which are sequentially connected; when the resin is filled into the hole, the side of the resin layer is placed on the PCB. This aluminum sheet adopts the three layer construction of resin layer, wood fiber layer and aluminium lamination, and the roughness is good, is difficult to corrugate and warp, conveniently tests the hole, and the thickness of resin layer is 0.02 ~ 0.03mm, and the resin layer mainly plays fixed drill point, prevents its effect of skidding off normal, and the resin layer mainly plays the effect that the clearance drill point bore dirt with wood fiber layer.
The invention does not need to carry out tinning, etching and tin stripping, shortens the flow, improves the production efficiency, and has the advantages that the back drilling cost can be reduced by 60 percent compared with the existing flow, and the quality of the manufactured back drilling hole is good.
Back drilling: if the length of the back drill is less than or equal to 0.3mm, the hole limit of the adopted drill bit is 500; if the length of the back drill is 0.31-0.5 mm, the hole limit of the adopted drill bit is 500; if the length of the back drill is 0.51-1.0 mm, the hole limit of the adopted drill bit is 500; if the length of the back drill is 1.01-1.5 mm, the hole limit of the adopted drill bit is 200; if the length of the back drill is 1.51-2.0 mm, the hole limit of the adopted drill bit is 150; if the back drill has a length of 2.1mm or more, the hole limit of the drill bit is 100. The hole limit is the service life of the drill bit adopted by the back drill, and when the service life is longer than the service life, another drill bit needs to be replaced, the hole wall quality after drilling is improved, and the copper layer needing to be removed in the hole can be completely cut off.
This embodiment is different from embodiment 1 or embodiment 2 in that: if the length of the back drill is less than or equal to 0.3mm, the feed speed is 1.8m/min, the withdrawal speed is 26m/min, and the rotating speed is 120krpm;
if the length of the back drill is 0.31-0.5 mm, the feed speed is 1.7m/min, the withdrawal speed is 25m/min, and the rotating speed is 115krpm;
if the length of the back drill is 0.51-1.0 mm, the feed speed is 1.6m/min, the withdrawal speed is 24m/min, and the rotating speed is 110krpm;
if the length of the back drill is 1.01-1.5 mm, the feed speed is 1.5m/min, the withdrawal speed is 23m/min, and the rotating speed is 105krpm;
if the length of the back drill is 1.51-2.0 mm, the feed speed is 1.4m/min, the withdrawal speed is 22m/min, and the rotating speed is 100krpm;
if the length of the back drill is more than or equal to 2.1mm, the feed speed is 1.2m/min, the withdrawal speed is 20m/min, and the rotating speed is 90krpm.
According to different back drilling depths, the cutter feeding speed, the cutter withdrawing speed and the rotating speed of the drilled hole are set, so that the quality of the drilled back drilled hole is ensured.
Example 3:
the embodiment provides a back drilling method for a PCB, which sequentially comprises the following steps: the method comprises the following steps of pre-processing, drilling, copper deposition, plate electric, back drilling, water washing, resin hole plugging and post-processing.
The former procedure comprises cutting the PCB.
Drilling, copper deposition and plate electric: and (4) manufacturing to form a PTH hole, and thickening the thickness of a copper layer on the surface of the PCB.
Back drilling: back drilling the PTH hole by using a back drill, and drilling the hole at one time if the length of the back drill is less than or equal to 0.3 mm; if the length of the back drill is 0.31-0.5 mm, the back drill is divided into 2 sections for drilling; if the length of the back drill is 0.51-1.0 mm, the back drill is divided into 3 sections for drilling; if the length of the back drill is 1.01-1.5 mm, the back drill is divided into 5 sections for drilling; if the length of the back drill is 1.51-2.0 mm, the back drill is divided into 6 sections for drilling; if the length of the back drill is more than or equal to 2.1mm, the back drill is divided into 7 sections for drilling. According to the different degree of depth of back drilling, adopt the mode of segmentation drilling to bore out the back drilling, improve the precision of back drilling, if need divide into the multistage and bore holes, the length of every section can be unanimous.
Washing with water: placing the PCB with the back drilling surface facing downwards, and sequentially performing hole plug removal, pressurized water washing I, ultrasonic water washing, HF water washing, high-pressure water washing and pressurized water washing II.
And (3) washing is carried out after back drilling, redundant copper scraps or residual copper wires on the back drilling hole are removed, the quality of the back drilling hole is ensured, and a washing effect is ensured by adopting two washing modes of pressurized water washing I, ultrasonic water washing, HF water washing, high-pressure water washing and pressurized water washing.
Resin hole plugging: an aluminum sheet is adopted for resin hole plugging, and the aluminum sheet comprises a resin layer, a wood fiber layer and an aluminum layer which are sequentially connected; when the resin is filled into the hole, the side of the resin layer is placed on the PCB.
This aluminum sheet adopts the three layer construction of resin layer, wood fiber layer and aluminium lamination, and the roughness is good, is difficult to corrugate and warp, conveniently tests the hole, and the thickness of resin layer is 0.02 ~ 0.03mm, and the resin layer mainly plays fixed drill point, prevents its effect of skidding off normal, and the resin layer mainly plays the effect that the clearance drill point bore dirt with wood fiber layer.
The invention does not need to carry out tinning, etching and tin stripping, shortens the flow, improves the production efficiency, and has the advantages that the back drilling cost can be reduced by 60 percent compared with the existing flow, and the quality of the manufactured back drilling hole is good.
Back drilling: if the length of the back drill is less than or equal to 0.3mm, the hole limit of the adopted drill bit is 500; if the length of the back drill is 0.31-0.5 mm, the hole limit of the adopted drill bit is 500; if the length of the back drill is 0.51-1.0 mm, the hole limit of the adopted drill bit is 500; if the length of the back drill is 1.01-1.5 mm, the hole limit of the adopted drill bit is 200; if the length of the back drill is 1.51-2.0 mm, the hole limit of the adopted drill bit is 150; if the length of the back drill is more than or equal to 2.1mm, the hole limit of the adopted drill bit is 100. The hole limit is the service life of the drill bit adopted by the back drill, and when the service life is longer than the service life, another drill bit needs to be replaced, the hole wall quality after drilling is improved, and the copper layer needing to be removed in the hole can be completely cut off.
This embodiment is different from embodiment 1 or embodiment 2 in that: the pressure for removing the hole plug is 0.55-0.75 MPa, preferably 0.65MPa, and the pressure for pressurized water washing is 1.5-2.5 kg/cm 2 The pressure adopted by ultrasonic water washing is 90bar, the error is +/-10 percent, and the pressure adopted by HF water washing is 1.5-2.5 kg/cm 2 The pressure of the HF washing is preferably 2.0kg/cm 2 The pressure adopted by the high-pressure water washing is 115-125 bar, and the pressure adopted by the pressurized water washing is 1.5-2.5 kg/cm 2 . The amplitude of the ultrasonic washing was 80KHZ. The washing method adopts two or more washing modes of pressurized water washing I, ultrasonic washing, HF washing, high-pressure washing and pressurized water washing to ensure the washing effect.
The invention does not need the etching process in the prior art, particularly does not need the processes of tinning, etching and stripping tin, and shortens the flow.
The PCB back drilling method provided by the invention does not need etching of the back drilling hole, shortens the process of manufacturing the back drilling hole and reduces the cost; according to the difference of the back drilling depth, different drilling modes and various water washing modes are adopted, so that the quality of the back drilling hole is improved; the aluminum sheet of resin consent is the three layer construction of resin layer, wood fibre layer and aluminium lamination, and the resin consent is effectual, is favorable to improving the quality of PCB board.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described above, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. A PCB back drilling method is characterized in that: the method sequentially comprises the following steps: the method comprises the following steps of a former procedure, drilling, copper deposition, plate electrification, back drilling, water washing, resin hole plugging and a later procedure;
the back drilling:
if the length of the back drill is less than or equal to 0.3mm, drilling at one time;
if the length of the back drill is 0.31-0.5 mm, the back drill is divided into 2 sections for drilling;
if the length of the back drill is 0.51-1.0 mm, the back drill is divided into 3 sections for drilling;
if the length of the back drill is 1.01-1.5 mm, the back drill is divided into 5 sections for drilling;
if the length of the back drill is 1.51-2.0 mm, the back drill is divided into 6 sections for drilling;
if the length of the back drill is more than or equal to 2.1mm, the back drill is divided into 7 sections for drilling;
and (3) washing: placing the PCB with the back drilling surface facing downwards, and sequentially performing hole plug removal, pressurized water washing I, ultrasonic water washing, HF water washing, high-pressure water washing and pressurized water washing II;
plugging holes with the resin: an aluminum sheet is adopted for resin hole plugging, and the aluminum sheet comprises a resin layer, a wood fiber layer and an aluminum layer which are sequentially connected; when the resin is filled into the hole, the side of the resin layer is placed on the PCB.
2. The PCB backdrilling method of claim 1, wherein: the thickness of the aluminum sheet is 0.46mm, and the error is +/-10%.
3. The PCB back drilling method of claim 1, wherein: the thickness of the aluminum layer is 0.12-0.14 mm.
4. The PCB back drilling method of claim 1, wherein: the back drilling:
if the length of the back drill is less than or equal to 0.3mm, the feed speed is 1.8m/min, the withdrawal speed is 26m/min, and the rotating speed is 120krpm;
if the length of the back drill is 0.31-0.5 mm, the feed speed is 1.7m/min, the withdrawal speed is 25m/min, and the rotating speed is 115krpm;
if the length of the back drill is 0.51-1.0 mm, the feed speed is 1.6m/min, the withdrawal speed is 24m/min, and the rotating speed is 110krpm;
if the length of the back drill is 1.01-1.5 mm, the feed speed is 1.5m/min, the withdrawal speed is 23m/min, and the rotating speed is 105krpm;
if the length of the back drill is 1.51-2.0 mm, the feed speed is 1.4m/min, the withdrawal speed is 22m/min, and the rotating speed is 100krpm;
if the length of the back drill is more than or equal to 2.1mm, the feed speed is 1.2m/min, the withdrawal speed is 20m/min, and the rotating speed is 90krpm.
5. The PCB back drilling method of claim 1, wherein: the back drilling:
if the length of the back drill is less than or equal to 0.3mm, the hole limit of the adopted drill bit is 500;
if the length of the back drill is 0.31-0.5 mm, the hole limit of the adopted drill bit is 500;
if the length of the back drill is 0.51-1.0 mm, the hole limit of the adopted drill bit is 500;
if the length of the back drill is 1.01-1.5 mm, the hole limit of the adopted drill bit is 200;
if the length of the back drill is 1.51-2.0 mm, the hole limit of the adopted drill bit is 150;
if the length of the back drill is more than or equal to 2.1mm, the hole limit of the adopted drill bit is 100.
6. The PCB back drilling method of claim 1, wherein: the pressure adopted by the pore-removing plug is 0.55-0.75 Mpa, and the pressure adopted by the pressurized water washing is 1.5-2.5 kg/cm 2 The pressure adopted by ultrasonic water washing is 90bar, the error is +/-10 percent, and the pressure adopted by HF water washing is 1.5-2.5 kg/cm 2 The pressure adopted by the high-pressure water washing is 115-125 bar, and the pressure adopted by the second pressurized water washing is 1.5-2.5 kg/cm 2 。
7. The PCB back drilling method of claim 1, wherein: the back drilling adopts the cutting edge length of a drill bit of 5.0mm.
8. A PCB board backdrilling method according to claim 1 or 7, wherein: and the back drill adopts an ST drill bit.
9. The PCB back drilling method of claim 1, wherein: the back drill adopts dust collection equipment to collect dust while drilling, and the used dust collection pressure is 17-20 KPa.
10. The PCB back drilling method of claim 1, wherein: and after washing, testing the back drilling hole of the PCB.
CN202211049882.1A 2022-08-30 2022-08-30 Back drilling method for PCB (printed circuit board) Pending CN115515336A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202211049882.1A CN115515336A (en) 2022-08-30 2022-08-30 Back drilling method for PCB (printed circuit board)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202211049882.1A CN115515336A (en) 2022-08-30 2022-08-30 Back drilling method for PCB (printed circuit board)

Publications (1)

Publication Number Publication Date
CN115515336A true CN115515336A (en) 2022-12-23

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202211049882.1A Pending CN115515336A (en) 2022-08-30 2022-08-30 Back drilling method for PCB (printed circuit board)

Country Status (1)

Country Link
CN (1) CN115515336A (en)

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