阅读说明：本技术 降低层压板翘曲度的方法 (Method for reducing warping degree of laminated board ) 是由 张玮 洪丹红 孙贵宝 张鹏辉 于 2021-07-29 设计创作，主要内容包括：本发明提供了一种降低层压板翘曲度的方法,包含：对具有应力的层压板施加振动。据此,本发明能够达到的技术效果在于,本发明提供了一种新的工艺方法,是可以和现有的覆铜板工艺进行融合,不需要改变现有工艺,可有效消除材料内部应力造成的翘曲,可节省较贵物料的压合开发成本,同时,在压合的过程中,进行应力消除工艺处理,可节省后续工艺步骤、生产时间,生产人力成本。(The invention provides a method for reducing warping degree of a laminated board, which comprises the following steps: applying vibration to the laminate having the stress. Therefore, the technical effect that the invention can achieve is that the invention provides a new process method which can be fused with the existing copper-clad plate process, the existing process is not required to be changed, the warping caused by the internal stress of the material can be effectively eliminated, the pressing development cost of the expensive material can be saved, meanwhile, the stress elimination process treatment is carried out in the pressing process, and the subsequent process steps, the production time and the production labor cost can be saved.)

1. A method of reducing warpage in a laminate, comprising: applying vibration to the laminate having the stress.

2. The method of claim 1, wherein the prepreg and the copper foil are cured by lamination to form a laminate, and the laminate is inspected with a stress inspection apparatus to determine whether stress is present in the laminate.

3. The method for reducing warpage in a laminate according to claim 2, wherein the number of prepreg layers is at least two.

4. The method for reducing warpage in a laminate according to claim 1,

the prepreg and the copper foil are laminated and cured by a vacuum hot press to form a laminated board;

the number of the laminated plates is N, and the laminating device comprises: the prepreg and the copper foil are positioned between two adjacent press plates, and the two adjacent press plates are relatively pressed and heated to carry out a lamination curing process;

vibration is applied to the laminate during the high temperature holding stage of the lamination curing process.

5. A method for reducing warpage in a laminate according to claim 4, wherein a frequency scanner is provided at the platen, which frequency scanner detects the resonant frequency of the laminate.

6. A method of reducing warpage in a laminate according to claim 4, wherein an exciter or resonator is provided at the laminate, the exciter or resonator producing excitation to apply vibration to the laminate.

7. A method for reducing warpage in a laminate according to claim 4, wherein an exciter or resonator is provided at the laminate, and a vibration feedback motion signal sensor is provided, the exciter or resonator vibrating the laminate at a plurality of frequencies, the vibration feedback motion signal sensor detecting the laminate feedback motion under excitation at each frequency, thereby obtaining the resonant frequency of the laminate.

8. A method of reducing warpage in a laminate board as claimed in claim 5 or claim 7, wherein the vibration is applied to the laminate board in dependence on a resonant frequency of the laminate board, the resonant frequency forming an input signal to the controller to set the frequency and power of the vibration applied to the laminate board.

9. The method for reducing warpage in a laminate according to claim 4,

the laminated board is transferred to a cooling process, two adjacent laminated boards are oppositely pressed to clamp the laminated board, and a stress detection instrument is adopted to detect the laminated board so as to determine whether stress exists in the laminated board;

if the presence of stress in the laminate is detected,

providing a frequency scanner at the platen, the frequency scanner detecting a resonant frequency of the laminate;

the resonant frequency is input to a controller,

an exciter or resonator is arranged at the pressure plate, and the controller forms an output signal according to an input signal formed by the resonant frequency so as to control the exciting frequency and the power of the exciter or the resonator.

10. A method of reducing warpage in a laminate as claimed in claim 6, 7 or 9, wherein the exciter or resonator is capable of being used in a temperature range of-18 ℃ to 380 ℃.

Technical Field

The invention relates to the field of circuit board manufacturing, in particular to a method for reducing warping degree of a laminated board.

Background

The PP sheet (prepreg) is bonded under heating, pressurizing and vacuum in the pressing process section, and the cooled laminated board is warped due to nonuniform internal stress of the PP sheet caused by nonuniform distribution of resin on two sides of the glass fiber cloth or other factors.

With the popularization of 5G and 6G products and the call of new national capital construction, the application of the ultrathin high-end high-frequency high-speed copper-clad plate is more and more extensive, and the market prospect is wide. In the process of preparing the ultrathin Copper-Clad plate, the subsequent processing and use of the Copper-Clad plate (CCL) can be influenced by the technical problems of warping and the like, so that the research on how to apply the ultrathin laminated plate to the manufacturing process of a Printed Circuit Board (PCB) is very convenient, and the method is very helpful for updating and popularizing products.

In the process of making copper-clad plates and circuit boards, the phenomenon of plate bending can occur sometimes. If the warping degree of the plate is too large, the use and the processing are affected, and in a serious case, the product is scrapped. The reason for causing the warping of the copper-clad plate is caused by residual thermal stress due to different thermal expansion coefficients of the reinforcing material and the matrix.

The prior art chinese patent document CN105873367A discloses a method for reducing warpage of a multilayer board, which includes a hot pressing process, wherein the hot pressing is performed by a high-low pressure pulse type pressurization method, and the high-low pressure pulse type pressurization includes an initial step type pressure increasing section, a first pressure decreasing section, and at least three pulse type pressurization processes. The traditional continuous high-pressure pressing mode is changed into high-low pressure pulse type pressing mode, the mode can increase the internal stress release window of the high-rise board, release most internal stress in a high-temperature environment to reduce the bending degree of the board, and effectively control the bending degree of the pressing board to be less than or equal to 0.75%, so that the product quality problems of difficult mounting, difficult soldering tin feeding, contact fracture and the like caused by the bending of the circuit board are obviously improved.

The prior art chinese patent document CN110913583A discloses a method for improving warpage of an asymmetric copper thick substrate and a substrate, comprising the steps of: when the CAM processing is carried out on the substrate with asymmetric copper thickness at the two ends of the insulating layer, the process edge segmentation processing is carried out on the thicker layer of copper, and if the substrate is still warped, the patterns at the two ends are increased and decreased according to the difference of the copper thickness quality at the two ends. The invention divides the end with larger copper thickness into small blocks by processing during CAM processing, thus reducing stress difference between layers and improving warping degree of the substrate.

The prior art chinese patent document CN107041069A discloses a method for correcting warpage of a PCB, comprising the steps of: carry out the bending with polylith PCB board to insert in proper order and insert the frame, mutual contactless between the PCB board, and the crooked direction of PCB board is opposite with the crooked direction of PCB board: and placing the inserting frame with the PCB into an oven to bake the PCB. According to the invention, the PCB subjected to warping is reversely bent and then is baked, so that the molecular structures of two surfaces of the PCB tend to be consistent, stress balance is achieved, the warping is corrected, the stability is good, the phenomenon that the warping is abnormal during subsequent high-temperature operation to cause layer deviation in subsequent pressing processing is avoided, the warping correction can be simultaneously performed on a plurality of boards, and the efficiency is high.

The following problems exist in the prior art: in the subsequent processing process of the PCB factory, similar temperature process adjustment is adopted, the surface appearance of the non-functional area is changed, such as ditching, punching and the like, for stress release, and the process steps are complex.

Disclosure of Invention

The technical problems to be solved by the invention are as follows: on the basis of not changing the existing copper-clad plate process, the internal stress of the copper-clad plate is eliminated; the time of the prior art is fully utilized, and the production time is saved; and the material is saved.

In order to solve the technical problems, the invention provides a method for reducing the warping degree of a laminated board, and aims to effectively eliminate the internal stress of the copper-clad board, save the production time and save the materials without changing the process of the existing copper-clad board.

In order to achieve the above object, the present invention provides a method for reducing warpage of a laminate, comprising: applying vibration to the laminate having the stress.

Preferably, the prepreg and the copper foil are cured by lamination to form a laminate, and the laminate is inspected with a stress inspection apparatus to determine whether stress is present in the laminate.

Preferably, the number of prepreg layers is at least two.

Preferably, the prepreg and the copper foil are cured by lamination using a vacuum hot press to form a laminate;

the number of the laminated plates is N, and the laminating device comprises: the prepreg and the copper foil are positioned between two adjacent press plates, and the two adjacent press plates are relatively pressed and heated to carry out a lamination curing process;

vibration is applied to the laminate during the high temperature holding stage of the lamination curing process.

Preferably, a frequency scanner is provided at the platen, which detects the resonant frequency of the laminate.

Preferably, an exciter or resonator is provided at the platen, which generates excitation to apply vibrations to the platen.

Preferably, an exciter or a resonator is arranged at the pressing plate, and a vibration feedback motion signal sensor is arranged, wherein the exciter or the resonator generates vibration of a series of frequencies to the pressing plate, and the vibration feedback motion signal sensor detects the feedback motion of the pressing plate under the excitation of each frequency, so that the resonance frequency of the pressing plate is obtained.

Preferably, the vibration is applied to the laminate in dependence on a resonant frequency of the laminate, which forms an input signal to the controller to set the frequency and power of the vibration applied to the laminate.

Preferably, the laminated plate is transferred to a cooling process, two adjacent laminated plates are oppositely pressed to clamp the laminated plate, and the laminated plates are detected by a stress detection instrument to determine whether stress exists in the laminated plate;

if the presence of stress in the laminate is detected,

providing a frequency scanner at the platen, the frequency scanner detecting a resonant frequency of the laminate;

the resonant frequency is input to a controller,

an exciter or resonator is arranged at the pressure plate, and the controller forms an output signal according to an input signal formed by the resonant frequency so as to control the exciting frequency and the power of the exciter or the resonator.

Preferably, the vibration exciter or the resonator can be used in a temperature range of-18 ℃ to 380 ℃.

Compared with the prior art, the invention provides a method for reducing warping degree of a laminated board, which comprises the following steps: applying vibration to the laminate having the stress. Therefore, the technical effect that the invention can achieve is that the invention provides a new process method which can be fused with the existing copper-clad plate process, the existing process is not required to be changed, the warping caused by the internal stress of the material can be effectively eliminated, the pressing development cost of the expensive material can be saved, meanwhile, the stress elimination process treatment is carried out in the pressing process, and the subsequent process steps, the production time and the production labor cost can be saved.

Drawings

Fig. 1 illustrates an embodiment of the method for reducing warpage in a laminate according to the present invention.

Description of reference numerals:

1 laminated plate

2 pressing plate

3 vibration exciter or resonator.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

The invention provides a method for reducing warping degree of a laminated board, which comprises the following steps: vibration is applied to the laminate 1 having stress. The method is also suitable for circuit boards formed by other wires or substrates in a pressing mode. For example, the applicant proposed various types of circuit boards such as wire-embedded circuit boards, circuit boards formed by engraving wires and then pressing. By applying vibrations to the laminate 1, vibrations of the laminate 1 will be induced, so that stresses in the laminate 1 are relieved. The vibration may be mechanical vibration, or acoustic vibration caused by mechanical vibration, and the vibration is transmitted to the laminate 1 through a solid, gas, or the like.

The prepreg and the copper foil are cured by lamination to form a laminate 1, and the laminate is inspected with a stress inspection apparatus to determine whether stress is present in the laminate. The prepreg may be one layer; accordingly, the copper foil may be one layer or two layers.

The number of layers of the prepreg is at least two. Accordingly, the method can also be applied to a multilayer board.

The prepreg and the copper foil are cured by lamination using a vacuum hot press to form a laminate. The prepreg is gradually hardened during the heating and pressing, and the copper foil is adhered to the prepreg.

The number of the laminated plates is N, and the laminating device comprises: and at least N +1 pressing plates 2, wherein the prepreg and the copper foil are positioned between two adjacent pressing plates, and the two adjacent pressing plates 2 are oppositely pressed and heated to carry out a laminating curing process. If the number of the pressing plates is 2, as in the case shown in fig. 1, one pressing plate can be pressed at the same time. However, every two press plates 2 can press one laminated plate 1. In the same lamination, the lamination process is basically performed on the same specification of the laminated board 1.

Vibration is applied to the laminate sheet 1 during the high-temperature holding stage of the lamination curing process. Therefore, the method for reducing the warping degree of the laminated board provided by the invention can be combined and applied to the existing pressing process without changing the existing pressing process.

A frequency scanner is provided at the platen, which detects the resonant frequency of the laminate.

At the press plate an exciter or resonator 3 is arranged, which exciter or resonator 3 generates an excitation to apply vibrations to the press plate 1.

A vibration exciter or a resonator 3 is arranged at the position of the laminated board, a vibration feedback motion signal sensor is arranged, the vibration exciter or the resonator 3 vibrates the laminated board 1 at a series of frequencies, and the vibration feedback motion signal sensor detects the feedback motion of the laminated board under the excitation of each frequency, so that the resonance frequency of the laminated board is obtained. Accordingly, a method of detecting a resonant frequency of a laminate using a frequency scanner is provided.

The resonant frequency forms an input signal to the controller to set the frequency and power of the vibration applied to the laminate, which is applied to the laminate, according to the resonant frequency of the laminate. As an excitation source, a large amplitude can be generated at the resonance frequency at the excitation frequency, and since the laminate has structural damping, infinite amplitude is not generated at the resonance frequency, and stress inside the laminate can be released by excitation close to the resonance frequency.

The laminated board is transferred to a cooling process, two adjacent laminated boards are pressed oppositely to clamp the laminated board, and a stress detection instrument is used for detecting the laminated boards to determine whether stress exists in the laminated board. The laminate was heated and pressed in a vacuum, and after curing, it was cooled. The press plate resembles a jig, but may be heated while the lamination process is performed in a vacuum heated press. In the cooling process, refrigeration or natural cooling may be used.

If the presence of stress in the laminate is detected. Since the process of vibration-relieving stress has been performed in the high-temperature holding stage of the lamination process, it is possible that stress is not already present in the laminate.

Arranging a frequency scanner at the pressing plate, wherein the frequency scanner detects the resonance frequency of the pressing plate;

the resonant frequency is input to the controller.

At the press plate an exciter or resonator 3 is arranged, and a controller forms an output signal from an input signal formed by the resonance frequency to control the excitation frequency and power of the exciter or resonator.

The vibration exciter or the resonator can be used in the temperature range of-18 ℃ to 380 ℃. Accordingly, the vacuum heating and pressing process and the cooling process in the laminate processing method can be adapted.

The above description is directed to embodiments of the present invention for reducing warpage in a laminate. Therefore, the method for reducing the warping degree of the laminated board can be fused with the existing vacuum heating and pressurizing process and cooling process of the copper-clad board and the like, the retention time (waiting time) is fully utilized, the existing process is not required to be changed, the warping caused by the internal stress of the material can be effectively eliminated, the pressing development cost of the expensive material can be saved, meanwhile, the stress eliminating process treatment is carried out in the pressing process, and the subsequent process steps, the production time and the production labor cost can be saved.

The above-mentioned embodiments and the accompanying drawings are only for illustrating the technical solutions and effects of the present invention, and are not to be construed as limiting the present invention. It is to be understood that those skilled in the art can modify and change the above-described embodiments without departing from the technical spirit and scope of the present invention as defined in the appended claims.