CN109696206B - Self-made buried resistance plate and testing method thereof - Google Patents

Abstract

The invention relates to a self-made embedded resistance board, which is a resistance board formed by pressing a core board and a copper foil containing resistance. Compared with the prior art, the invention has the advantages of lower price cost, higher reliability and the like.

Description

Self-made buried resistance plate and testing method thereof

Technical Field

The invention relates to the field of PCB (printed circuit board) manufacturing, in particular to a self-made buried resistor plate and a testing method thereof.

Background

Along with the aggravation of high frequency and high performance of electronic products, the problem of internal electromagnetic interference resistance is increasingly prominent. The minimum device which can be processed by the SMT technology at present is 0201, and the lead between a capacitor, a resistor and an active device is short, even if the transmission frequency of digital signals exceeds hundreds of MHz, parasitic inductance of the resistor and the capacitor lead has great influence on the signal quality.

On the other hand, because the resistor and the capacitor occupy most of the components, the downstream process of the PCB is mounted and plugged with a lot of troubles. And the general resistance heating power is also less, and the design and the manufacture of the PCB are an unprecedented technical revolution.

Because the cost of materials and production and manufacturing is high, the application of the buried resistor products in the industry is limited to military industry, satellite communication, microwave communication, optical fiber communication and the use of high-speed computers, therefore, the content and the purpose of the project improve the comprehensive performance of the buried resistor copper foil mixed-pressing product by a technical improvement mode, and replace the high-cost buried resistor materials. The method provides technical support in the aspect of buried resistance for the continuous development of electronic information products in high density, high difficulty, high frequency and high speed, and the project has wide market prospect.

Through search, chinese patent publication No. CN108012447A discloses a mounting process for semiconductor-packaged multilayer organic substrates, which comprises the following steps: and (3) upper plate: feeding the unfinished PCB substrate onto a workbench of a production line through a plate feeding device; dispensing: dripping glue on a bonding pad of the PCB by a glue dispenser; mounting: mounting the electronic components on the corresponding positions of the PCB by using a chip mounter; and (3) curing: sending the PCB board with the mounted electronic components into a curing furnace for thermosetting to fixedly bond the electronic components and the PCB board together; mounting and detecting: and carrying out welding quality detection and assembly quality detection on the PCB assembled with the electronic components. The manufacturing period is shortened, the cost is reduced, and the substrate and the mounting process are completed inside, so that the quality and the efficiency are improved. However, in the invention, the electronic components are mounted on the corresponding positions of the PCB through the chip mounter, wherein the resistors and the capacitors account for most of the electronic components, and the operation is complicated.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a self-made buried resistor plate and a testing method thereof.

The purpose of the invention can be realized by the following technical scheme:

the self-made embedded resistance board is formed by pressing a core board and a copper foil containing resistance.

Preferably, the core board is a combination of prepregs with different models.

Preferably, the prepregs adopt various series of prepregs of ROGERS or TACONIC.

Preferably, the copper foil with resistance is a resistance copper foil manufactured by omega HMEGA company.

Preferably, the core board and the copper foil containing the resistor are pressed into the embedded resistor board through an FR-4 pressing procedure.

A testing method for a self-made buried resistance plate comprises the following steps:

(1) testing the flatness of the pressed plate;

(2) testing the peel strength of the pressed plate;

(3) testing the thermal stress capability of the pressed plate;

(4) and (5) pressing the resistance layer of the plate to etch out the resistance precision test.

Preferably, the flatness test of the pressed plate is as follows: and measuring the thickness of the laminated plate by averaging 12 points at the periphery and in the middle of the plate surface, and checking the flatness or the plate thickness deviation of the plate.

Preferably, the peel strength test of the pressed board specifically comprises: taking a half of the pressed plate, taking an FR-4 plate with the same size and model number of 0.51MM and 18/18 and an embedded resistance plate with 50 ohm resistance and the copper thickness of the outer layer of 18 microns, simultaneously and directly etching the three plates to form lines with the line width of 1.0MM, the line width of 1.8MM and the length of 2.5MM of 80MM, and comparing to determine the anti-stripping strength of the self-made plate.

Preferably, the test of the thermal stress capability of the pressed plate is as follows: pressing into a plate, dividing the plate into two parts, wherein each part is provided with an etched area and an unetched area, half of the plate is dried at 150 ℃ for 1 hour, and half of the plate is immersed in a tin furnace at 288 ℃ for 3 times for 10 seconds each time without drying, and testing the thermal stress capability.

Preferably, the test of the etched resistance precision of the pressed resistance layer of the plate is as follows:

the purchased embedded resistor copper foil has a resistance value of square resistor of 50 ohms, square resistor block films with different side lengths are designed, the other half of the board is pressed into the other half of the board, the square resistor blocks with resistors of 50 ohms in different sizes are etched according to a normal etching resistance process, the resistance values of the resistor blocks are measured and compared, and the uniformity and accuracy of the etching resistance are checked.

The principle of the invention is as follows: the prepreg with different types can be used for combining as a core board and a resistance copper foil to carry out pressing according to different design requirements, so that a resistance-containing plate is replaced, and the function of mounting various resistance components is replaced. The high-reliability high-power LED lamp is low in price cost and high in reliability, and can be widely used in the civil field.

Compared with the prior art, the invention has the following advantages:

1. advantages in high density/high speed transmission circuit design:

(a) improving the impedance matching of the circuit;

(b) the signal transmission path is shortened, and parasitic inductance is reduced;

(c) the inductive reactance generated in the surface mounting or inserting process is eliminated;

(d) reducing signal crosstalk, noise and electromagnetic interference.

2. The advantages in replacing the mounted resistor are as follows:

(a) passive components are reduced, and the mounting density of active components is improved;

(b) the Via holes are reduced, so that the wiring capacity of the board surface is improved;

(c) because the number of solder joints is reduced, the stability of the assembled electrical device is improved.

3. The integrated buried resistor has the advantages in stability:

(a) the loss of the buried resistor after the cold-hot circulation is very low, about 50PPM, and the loss of other separated resistor components is 100-300 PPM;

(b) after the material is stored for 10000 hours under the condition of 110, the resistance is increased by about 2 percent;

(c) the stability test is carried out in a wide frequency range and is less than 20G HZ.

4. The resistance values of various specifications can be synthesized by simply adjusting the external dimensions of the resistor, and the resistor can be completely matched with the line inductance.

5. In the component for designing the high-density separation resistor, the embedded resistor technology is adopted, so that the cost can be greatly saved, and the repair work can be reduced.

6. The buried resistor technology can reduce the number of layers and size of the PCB, reduce the weight and manufacturing cost of the PCB and be widely applied to manufacturing civil products.

Drawings

Fig. 1 is a laminated diagram of a self-made buried resistor board according to an embodiment of the present invention;

FIG. 2 is a point-taking position diagram of the measured plate thickness on the self-made buried resistance plate according to the embodiment of the present invention;

FIG. 3 is a graph comparing measured plate thickness and average value data on the self-made buried resistor plate according to the embodiment of the present invention;

fig. 4 is a picture of a number 1 square stop block with a larger square stop side in the middle of any board surface according to the embodiment of the present invention;

fig. 5 is a picture of a number 2 square stop blocks with a larger square stop side in the middle of any board surface according to the embodiment of the present invention;

fig. 6 is a picture of a number 3 square stop block with a larger square stop side in the middle of any board surface according to the embodiment of the present invention;

fig. 7 is a picture of a number 4 square stop blocks with a larger square stop side in the middle of any board surface according to the embodiment of the present invention;

fig. 8 is a picture of a number 5 of square resistor blocks with a larger square resistor side in the middle of any board surface according to the embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be made clear and fully described below, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.

As shown in fig. 1, two sheets 7628 and two sheets 3313 of conventional FR-4 were used as core sheets, one sheet containing resistors of 10 '× 8' size was laminated using a conventional 12 micron copper foil and one sheet containing resistors of 18 micron copper foil using a conventional FR-4 lamination process.

The performance of the self-made plate is subjected to four aspects of basic test and inspection by combining IPC-4101A rigid and substrate specification requirements for multilayer printed plates, and the four aspects of basic test and inspection comprise the following steps:

(1) flatness (plate thickness deviation) of the pressed plate;

(2) peel strength of the pressed board;

(3) the thermal stress capability of the pressed sheet;

(4) and pressing the resistance layer of the plate to etch the resistance precision.

Four test experiments are divided according to the index requirements:

(1) and measuring the thickness of the laminated plate by averaging 12 points at the periphery and the middle of the plate surface, and checking the flatness (plate thickness deviation) of the plate.

(2) Taking one half of the self-made plate, taking another ordinary FR-4 plate with the same size and model number of 0.51MM 18/18 and a buried resistance plate which is purchased by a company and has 50 ohm resistance and 18-micron copper thickness of the outer layer, simultaneously and directly etching the three plates to form lines with the line width of 1.0MM, the line width of 1.8MM and the length of 2.5MM of 80MM, and comparing to determine the anti-stripping strength of the self-made plate.

(3) The self-made plate after the test is divided into two parts (each part is provided with an etched area and an unetched area), the plate is baked at the temperature of 150 ℃ for 1 hour for half, the plate is not baked, and the plate is immersed in a tin furnace at the temperature of 288 ℃ for 3 times for 10 seconds each time, and the thermal stress capability is tested.

(4) The purchased embedded resistance copper foil is the square resistance 50 ohm resistance value, square resistance block films with different side lengths are designed (compensation is not carried out), square resistance blocks with different resistances of 50 ohm are etched on the other half of the self-made plate according to the normal etching resistance process, the resistance values of the resistance blocks are measured and compared, and the uniformity and the accuracy of the etching resistance are tested.

Results and analysis of four tests:

(1) flatness measurement of sheet thickness:

the plate thickness was measured at the spot locations shown in fig. 2 on the home-made resistor-containing plates with dimensions 10 'by 8', and the measurement results are shown in table 1:

TABLE 1 thickness of self-made plate at different points (Unit: MM)

1	2	3	4
				0.633	0.692	0.651	0.631
5	6	7	8
				0.675	0.739	0.726	0.698
9	10	11	12
				0.645	0.711	0.730	0.671

And (4) analyzing results:

all sheet thickness values were averaged to 0.691MM and all data were plotted against the average as shown in figure 3: the maximum plate thickness deviation is 0.06MM and 0.048MM, and the standard plate thickness deviation value of K level according to the thickness grade of the laminated plate is +/-0.075MM, so that the flatness of the laminated plate is ideal under the current production and manufacturing conditions.

(2) Peel strength test:

the comparison copper thickness is 18 microns 1, the common FR-4 board 2, the embedded resistance board 3 is purchased, the three board types 4 of the self-made embedded resistance board, the peel strength of the copper foil of the 12-micron copper surface on the other surface of the self-made embedded resistance board are 4, and the measurement results are shown in the table 2:

TABLE 2 Peel resistance of different sheets (unit: kg/cm)

And (4) analyzing results:

according to the standard of the peeling strength of the laminated board, the peeling strength standard of the copper foil with the copper thickness of 18 microns or less is more than or equal to 1.07kg/cm, and the comparison of the data in the table 2 shows that the peeling strength of the common FR-4 board, the purchased embedded resistance board, the 18 micron resistance copper surface of the self-made embedded resistance board and the 12 micron copper surface of the self-made embedded resistance board are all more than 1.07kg/cm, so that the requirement of the peeling strength of the laminated board is met.

(3) Thermal stress test:

after a simple thermal stress test, the conditions of the two plate surfaces are visually inspected, and the results are analyzed as follows:

the two boards which pass through the drying plate and do not pass through the drying plate have no bad phenomena of plate explosion, foaming, resin softening, fine cracks, cavities, resin lack and the like, and the basic thermal stress capability of the test board is qualified.

(4) Testing the uniformity and accuracy of the etching resistance of the self-made buried resistance plate:

(4.1) taking a plurality of square resistance blocks with larger square resistance side length in the middle of the plate surface, and measuring the resistance value, wherein the data are as follows:

TABLE 3 different size Square Block resistance results

And (4) analyzing results:

the design sheet resistance is 50 ohm, and comparing the resistance results in table 3, the actual etched sheet resistance is within 2 ohm (removing individual abnormal value) of the design value, and the requirement that the etching resistance value is controlled within 5% is achieved, which shows that the etched sheet resistance block from the self-buried resistance plate meets the process standard requirement.

(4.2) selecting a plurality of square stop blocks with larger square stop edge length in the middle of the plate surface, measuring the actual edge length value of the etched square stop blocks and combining the actual edge length value with the square stop block picture; the measurement results are shown in the following table 4:

TABLE 4 actual edge length values (unit: MM) of different size square blocks

The pictures of each group of etched square resistor blocks are shown in fig. 4-8, namely the condition that the resistor blocks are shot under a high-power electronic magnifier in the test.

And (4) analyzing results:

according to the data, the edge length phase difference of the etched square resistor block is about 1MIL, and the accuracy of the resistance value is verified.

The conclusion is drawn from four test tests:

1. the surface of the resistance plate extruded by the self-laminating method is free of pinholes, concave points and dents, the copper sheet wrinkling phenomenon is caused at the middle position of the surface, the flatness of the whole plate is +/-0.075MM according to the thickness grade K-level standard plate thickness deviation value of the laminated plate, and the flatness of the laminated plate is ideal under the existing production and manufacturing conditions.

2. Compared with the results of peel strength tests of ordinary FR-4 plates, purchased embedded resistance plates, copper foils with 12-micron copper surfaces of the self-made embedded resistance plates and copper foils with 18-micron copper surfaces of the self-made embedded resistance plates, the peel strength of the copper foils on the resistance copper surfaces of the self-made embedded resistance plates exceeds the requirement of 1.07kg/cm, and the peel strength is qualified.

3. After the self-made buried resistance board is subjected to a thermal stress test, the self-made buried resistance board has no bad phenomena of board explosion, foaming, resin softening, fine cracks, cavities, resin shortage and the like, and the basic thermal stress capability of the test board is qualified.

4. The difference between the actual etching result of the sheet resistance of the self-made buried resistor board and the design value is within 2 ohms, the requirement that the resistance value is controlled within 5 percent is met, the etching graph is more regular, and the resistance precision meets the requirement.

While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (8)

1. The test method of the self-made buried resistance board is characterized in that the buried resistance board is a resistance board formed by pressing a core board and a copper foil containing resistance, and the test method comprises the following steps:

(1) testing the flatness of the pressed plate;

(2) testing the peel strength of the pressed plate;

(3) testing the thermal stress capability of the pressed plate;

(4) pressing into a plate resistance layer to etch out resistance precision test;

the peel strength test of the pressed plate is as follows: taking a half of the pressed plate, taking an FR-4 plate with the same size and model number of 0.51MM and 18/18 and an embedded resistance plate with 50 ohm resistance and the copper thickness of the outer layer of 18 microns, simultaneously and directly etching the three plates to form lines with the line width of 1.0MM, the line width of 1.8MM and the length of 2.5MM of 80MM, and comparing to determine the anti-stripping strength of the self-made plate.

2. The test method according to claim 1, wherein the core board is a combination of prepregs with different types.

3. The test method according to claim 2, wherein the prepregs used are ROGERS or TACONIC series prepregs.

4. The method as claimed in claim 1, wherein the resistive copper foil is a resistive copper foil manufactured by omega HMEGA.

5. The test method of claim 1, wherein the core board and the copper foil with the resistor are pressed into the embedded resistor board by an FR-4 press process.

6. The test method according to claim 1, wherein the flatness test of the pressed board is specifically as follows: and measuring the thickness of the laminated plate by averaging 12 points at the periphery and in the middle of the plate surface, and checking the flatness or the plate thickness deviation of the plate.

7. The test method according to claim 1, wherein the test for the thermal stress capability of the pressed sheet material is specifically as follows: pressing into a plate, dividing the plate into two parts, wherein each part is provided with an etched area and an unetched area, half of the plate is dried at 150 ℃ for 1 hour, and half of the plate is immersed in a tin furnace at 288 ℃ for 3 times for 10 seconds each time without drying, and testing the thermal stress capability.

8. The test method according to claim 1, wherein the test of the etched resistance precision of the pressed resistive layer of the plate is as follows:

the purchased embedded resistor copper foil has a resistance value of square resistor of 50 ohms, square resistor block films with different side lengths are designed, the other half of the board is pressed into the other half of the board, the square resistor blocks with resistors of 50 ohms in different sizes are etched according to a normal etching resistance process, the resistance values of the resistor blocks are measured and compared, and the uniformity and accuracy of the etching resistance are checked.

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