CN113727517B - Method for improving thickness uniformity of PCB (printed circuit board) and inner-layer circuit board glue flowing groove structure - Google Patents

Method for improving thickness uniformity of PCB (printed circuit board) and inner-layer circuit board glue flowing groove structure Download PDF

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CN113727517B
CN113727517B CN202111033755.8A CN202111033755A CN113727517B CN 113727517 B CN113727517 B CN 113727517B CN 202111033755 A CN202111033755 A CN 202111033755A CN 113727517 B CN113727517 B CN 113727517B
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circuit board
glue flowing
groove
inner layer
pcb
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CN113727517A (en
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梁鸿飞
陈世金
许伟廉
黄伟
廖金超
巫中山
郭茂桂
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BOMIN ELECTRONICS CO LTD
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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
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0272—Adaptations for fluid transport, e.g. channels, 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
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0296—Conductive pattern lay-out details not covered by sub groups H05K1/02 - H05K1/0295
    • H05K1/0298—Multilayer circuits
    • 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
    • H05K3/46—Manufacturing multilayer circuits
    • H05K3/4602—Manufacturing multilayer circuits characterized by a special circuit board as base or central core whereon additional circuit layers are built or additional circuit boards are laminated

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  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Production Of Multi-Layered Print Wiring Board (AREA)

Abstract

The invention discloses a method for improving the thickness uniformity of a PCB (printed circuit board) and an inner layer circuit board glue flowing groove structure, and relates to a PCB manufacturing process. Aiming at the problem of great plate thickness difference in the prior art, the scheme is provided, wherein a central glue flowing groove is respectively arranged in the center positions of four sides of a glue flowing groove area, and a plurality of glue flowing grooves are symmetrically arranged on two sides of the central glue flowing groove; in the same edge, the distance between adjacent glue flowing grooves increases from the central glue flowing groove to the two sides in an equal ratio; all the glue flowing grooves are respectively communicated with the inner side and the outer side of the glue flowing groove area. The thickness uniformity of the printed circuit board is improved, so that the thickness range of a product with the thickness of 2.4mm is reduced by about 40% compared with the prior art.

Description

Method for improving thickness uniformity of PCB (printed circuit board) and inner-layer circuit board glue flowing groove structure
Technical Field
The invention relates to a PCB manufacturing process, in particular to a method for improving the thickness uniformity of a PCB and an inner layer circuit board glue flowing groove structure.
Background
The multilayer printed circuit board is formed by laminating a plurality of wiring layers and a plurality of dielectric layers, and each layer is made to be very thin. The prior art can control the whole plate thickness of a dozen or twenty layers of circuit boards within 2 mm. With the higher and higher requirements for the refinement of electronic products, the requirement for the uniformity of the overall plate thickness is also improved. When the requirement of the product design on the uniformity of the plate thickness is high, the requirement of the product cannot be met due to insufficient uniformity of the plate thickness, and the yield of the product is influenced. And the better the uniformity control of the thickness of the inner plate in one batch, the higher the stability of the corresponding product.
The index for evaluating the uniformity of the sheet thickness generally includes a range, a relative mean deviation, a relative standard deviation, and the like. The level of the prior art is to make the range of a batch of hundreds of multilayer PCBs about 0.12mm, the relative range of the PCBs is as high as 10%, and the relative average deviation and the relative standard deviation are both more than 2.5%.
The multilayer printed circuit board is manufactured by a lamination method, and core boards (namely inner layer circuit boards) are bonded by prepregs: and (3) pre-laminating the core board, the prepreg and the copper foil, and then pressing at high temperature to form a multilayer board. In the pressing process, the prepreg made of the resin is converted into a flowing state at high temperature, and partial resin flows out of the four sides of the core plate. And bonding the core plates on the two sides after the resin is cured.
The uniformity of the resin flow directly and seriously affects the thickness uniformity of the entire multilayer PCB. In order to improve and control the glue flowing effect, glue flowing groove areas 11 are arranged on four sides of the inner-layer circuit board 10, then a plurality of glue flowing grooves 12 are arranged in the glue flowing groove areas 11, and the glue flowing grooves 12 are communicated with two sides of the glue flowing groove areas 11, as shown in fig. 1.
The conventional board edge runner design has three types, namely an elongated runner structure as shown in fig. 2, a rectangular runner structure as shown in fig. 3 and a hexagonal runner structure as shown in fig. 4.
However, the glue flowing effect of the glue flowing grooves is not uniform enough, and the uniformity of the whole plate thickness cannot be ensured.
Under the same process and material configuration, the slender glue flowing groove structure, the rectangular glue flowing groove structure and the hexagonal glue flowing groove structure are respectively used for manufacturing 120 pieces of multilayer printed circuit boards on one side of a product with the thickness of 2.4 mm. The following sheet thickness data were obtained:
Figure BDA0003246327390000011
Figure BDA0003246327390000021
Figure BDA0003246327390000022
Figure BDA0003246327390000023
disclosure of Invention
The invention aims to provide a method for improving the thickness uniformity of a PCB (printed circuit board) and an inner layer circuit board glue flowing groove structure, so as to solve the problems in the prior art.
The invention provides a method for improving the thickness uniformity of a PCB (printed circuit board) and an inner-layer circuit board glue flowing groove structure, comprising an inner-layer circuit board, wherein glue flowing groove areas are arranged on four sides of the inner-layer circuit board; the central positions of four sides of the gummosis groove area are respectively provided with a central gummosis groove, and a plurality of gummosis grooves are symmetrically arranged on two sides of the central gummosis groove; in the same edge, the distance between adjacent glue flowing grooves increases from the central glue flowing groove to the two sides in an equal ratio; all the glue flowing grooves are respectively communicated with the inner side and the outer side of the glue flowing groove area.
The distance A between the central gummosis groove and the adjacent gummosis grooves meets the formula:
a ═ 0.5 × [ L1-2 × L4- (2n +1) × L3] (1-x)/(1-x ^ n); wherein, L1 is the length of the long side of the inner layer circuit board, x is the proportionality coefficient that the equal ratio increases gradually, L3 is the groove width of the gummosis groove, n is the number of gummosis grooves on one side of the central gummosis groove, and L4 is the length reserved at both ends of the long side respectively.
The scaling coefficient x of the geometric progression is 2.5-4, preferably 3.25.
The groove width L3 is 1-5 mm, preferably 3 mm.
The number n of the glue flowing grooves is 3-5, and preferably 4.
The length L4 is 24.1 mm.
A method for improving the thickness uniformity of a PCB utilizes the inner layer circuit board glue flowing groove structure for improving the thickness uniformity of the PCB to carry out glue flowing operation.
The method for improving the thickness uniformity of the PCB and the inner layer circuit board glue flowing groove structure have the advantages that the thickness uniformity of the PCB is improved, and the thickness range of a product with the thickness of 2.4mm is reduced by about 40% compared with the prior art.
Drawings
FIG. 1 is a schematic diagram of a glue flow groove structure of an inner-layer circuit board in the prior art;
FIG. 2 is an enlarged view of the structure at K in FIG. 1;
FIG. 3 is an enlarged view of the structure at K in FIG. 1;
fig. 4 is an enlarged view of the structure at K in fig. 1.
FIG. 5 is a schematic view of the structure of the glue flowing groove of the inner layer circuit board;
fig. 6 is a schematic diagram of a distance relationship of the inner layer circuit board glue flowing groove structure.
Reference numerals:
10-inner layer circuit board, 11-glue flowing groove area and 12-glue flowing groove;
21-a central gummosis groove, 22-a second gummosis groove, 23-a third gummosis groove, 24-a fourth gummosis groove and 25-a fifth gummosis groove;
l1-the length of the long side of the inner layer circuit board, L2-the length of the short side of the inner layer circuit board;
a-the distance between the central glue flowing groove and the second glue flowing groove;
b-the distance between the second glue flowing groove and the third glue flowing groove;
c, the distance between the third glue flowing groove and the fourth glue flowing groove;
d, the distance between the fourth gummosis groove and the fifth gummosis groove.
Detailed Description
According to the method for improving the thickness uniformity of the PCB and the inner-layer circuit board gumming groove structure, the gumming groove is gradually reduced in density when extending from the middle points of the four sides to the two sides, so that the middle sections of the four sides can be effectively and fully gummed, and the gumming groove structure is balanced with gumming at the four corners, and the thickness uniformity of the PCB is improved.
The specific implementation steps are as follows:
1. when the inner layer graph is manufactured, glue flowing grooves with gradually changed intervals are designed at the plate edges;
2. and pre-laminating the multilayer inner core board and the prepreg, and pressing the laminated core board and the prepreg into a multilayer board by using a press.
As shown in fig. 5, the laminated multilayer board specifically includes an inner layer circuit board 10, and four sides of the inner layer circuit board 10 are provided with runner areas 11. The central glue flowing groove 21 is respectively arranged in the central positions of the four sides of the glue flowing groove area 11, and a plurality of glue flowing grooves are symmetrically arranged on two sides of the central glue flowing groove 21. In the same side, the distance between the adjacent glue flowing grooves increases from the central glue flowing groove 21 to the two sides in an equal ratio. All the runner channels communicate with the inside and outside of the runner channel region 11, respectively.
The distance A between the central gummosis bath 21 and the adjacent gummosis baths satisfies the formula:
a is 0.5 ═ L1-2 ^ L4- (2n +1) × L3] (1-x)/(1-x ^ n). Wherein; l1 is the length of the long side of the inner-layer wiring board 10; x is a scaling factor with an increasing ratio, i.e., x-D/C-C/B-B/a, as shown in fig. 6; l3 is the slot width of the gummosis slot; n is the number of the gummosis dipping baths on one side of the central gummosis dipping bath 21; l4 is a length reserved at each end of the long side.
The scaling coefficient x of the geometric progression is 2.5-4, preferably 3.25.
The groove width L3 is 1-5 mm, preferably 3 mm.
The number n of the glue flowing grooves is 3-5, and preferably 4. When n is 4, the glue flowing grooves with the long sides on two sides of the central glue flowing groove 21 are a second glue flowing groove 22, a third glue flowing groove 23, a fourth glue flowing groove 24 and a fifth glue flowing groove 25 in sequence.
The length L4 is 24.1 mm.
Regarding the values of the short side: the proportionality coefficient, the groove width and the A value are the same as those of the long edge, and the number n of the gummosis grooves is selected to be the same as that of the long edge or reduced by 1 compared with that of the long edge according to actual arrangement. Let n-1 for the short side when the short side length L2 is not sufficient to set n equal to the long side.
In the industry, L1 is used more for 550mm plate size. The following specific example selection parameters are given:
Figure BDA0003246327390000051
on the basis of the preferred values, i.e. the values corresponding to example 14, a single plate of 2.4mm thickness was tested for 120 plate thickness tests, the specific results being shown in the following table:
Figure BDA0003246327390000052
Figure BDA0003246327390000061
therefore, compared with the prior art, the inner-layer circuit board glue flowing groove structure can reduce the extreme difference to 0.075mm, and obviously reduces the minimum difference by 36.4 percent compared with the prior art.
It will be apparent to those skilled in the art that various other changes and modifications may be made in the above-described embodiments and concepts and all such changes and modifications are intended to be within the scope of the appended claims.

Claims (9)

1. An inner layer circuit board gummosis groove structure for improving the thickness uniformity of a PCB comprises an inner layer circuit board (10), wherein gummosis groove areas (11) are arranged on four sides of the inner layer circuit board (10);
the glue flow groove is characterized in that a central glue flow groove (21) is respectively arranged in the center positions of four sides of the glue flow groove area (11), and a plurality of glue flow grooves are symmetrically arranged on two sides of the central glue flow groove (21); in the same side, the distance between the adjacent glue flowing grooves increases from the central glue flowing groove (21) to the two sides in an equal ratio; all the gummosis baths are respectively communicated with the inner side and the outer side of the gummosis bath area (11);
the distance A between the central gummosis bath (21) and the adjacent gummosis bath meets the formula:
A＝0.5*[L1-2*L4-(2n+1)*L3]*(1-x)/(1-x^n)；
wherein, L1 is the length of the long edge of the inner layer circuit board (10), x is the proportionality coefficient of the equal ratio increasing, L3 is the width of the glue flowing groove, n is the number of the glue flowing grooves on one side of the central glue flowing groove (21), and L4 is the length reserved at the two ends of the long edge respectively.
2. The inner layer circuit board gumming groove structure for improving PCB plate thickness uniformity as claimed in claim 1, wherein the proportionality coefficient x of equal ratio increasing is 2.5-4.
3. The inner layer circuit board gumming groove structure for improving PCB plate thickness uniformity as claimed in claim 2, wherein the proportionality coefficient x of equal ratio progressive increase is 3.25.
4. The inner layer board gumming groove structure for improving PCB plate thickness uniformity as claimed in claim 1, wherein the groove width L3 is 1-5 mm.
5. The inner layer board gumming groove structure for improving PCB plate thickness uniformity as claimed in claim 4, wherein the groove width L3 is 3 mm.
6. The inner layer circuit board glue flowing groove structure for improving the PCB thickness uniformity as claimed in claim 1, wherein the number n of the glue flowing grooves is 3-5.
7. The inner layer board gumming groove structure for improving the PCB board thickness uniformity as claimed in claim 6, wherein the number n of gumming grooves is 4.
8. The flow groove structure of inner layer circuit board for improving PCB thickness uniformity as recited in claim 1, wherein said length L4 is 24.1 mm.
9. A method for improving the uniformity of the thickness of a PCB, characterized in that the glue flowing operation is carried out by using the inner layer circuit board glue flowing groove structure for improving the uniformity of the thickness of the PCB according to any one of claims 1 to 8.
CN202111033755.8A 2021-09-03 2021-09-03 Method for improving thickness uniformity of PCB (printed circuit board) and inner-layer circuit board glue flowing groove structure Active CN113727517B (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN202190457U (en) * 2011-08-24 2012-04-11 胜宏科技（惠州）有限公司 High-uniformity circuit board
CN207305060U (en) * 2017-10-18 2018-05-01 常州安泰诺特种印制板有限公司 High-power used in base station antenna Multifunctional printing wiring board
CN210202171U (en) * 2019-04-09 2020-03-27 智恩电子(大亚湾)有限公司 Multilayer PCB structure with uniform plate thickness
CN112601355A (en) * 2020-11-07 2021-04-02 奥士康科技股份有限公司 Processing method and structure of copper-embedded block

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7488526B2 (en) * 2005-11-22 2009-02-10 Ricoh Company, Ltd. Sputtering target and manufacturing method therefor, and optical recording medium and manufacturing method therefor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN202190457U (en) * 2011-08-24 2012-04-11 胜宏科技（惠州）有限公司 High-uniformity circuit board
CN207305060U (en) * 2017-10-18 2018-05-01 常州安泰诺特种印制板有限公司 High-power used in base station antenna Multifunctional printing wiring board
CN210202171U (en) * 2019-04-09 2020-03-27 智恩电子(大亚湾)有限公司 Multilayer PCB structure with uniform plate thickness
CN112601355A (en) * 2020-11-07 2021-04-02 奥士康科技股份有限公司 Processing method and structure of copper-embedded block

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