Evaluation method for compatibility of welding material for electronic assembly and electronic adhesive

Abstract

The invention relates to a method for evaluating the compatibility of a welding material for electronic assembly and an electronic adhesive, and the method comprises the following steps: coating a to-be-tested welding material and an electronic adhesive on a printed circuit board, and enabling the welding material to be in contact with the electronic adhesive to obtain a to-be-tested sample plate; performing a temperature cycle environment test and a humid and hot environment test on the to-be-tested sample plate to obtain a test sample plate; obtaining the difference between the physicochemical properties of the welding material and the electronic adhesive before and after the test, wherein the physicochemical properties comprise at least one of surface appearance, conductivity, organic matrix material components, thermal decomposition temperature, surface insulativity and appearance at the interface of the welding material and the electronic adhesive; and evaluating the compatibility between the welding material and the electronic adhesive according to the difference of the physicochemical properties. According to the method, compatibility evaluation dimensions and standards of the welding material and the electronic adhesive are provided, and risks of short circuit, degumming, failure and the like of electronic products are reduced.

Description

Technical Field

[0001] This invention relates to the field of testing and evaluation technology, and in particular to a method for evaluating the compatibility of electronic assembly welding materials and electronic adhesives. Background Technology

[0002] With the rapid development of electronic products in industries such as 5G communication, artificial intelligence, quantum computing, and the Internet of Things, the application of electronic assembly materials is becoming increasingly widespread. A single electronic product often includes soldering materials, electronic adhesives (such as underfill, side filler, potting compound, fixing compound, and surface mount adhesive), cleaning materials, thermal interface materials, conformal coating materials, and other types of electronic assembly materials. Due to the complexity of electronic assembly materials and the intricate reactions between fine chemicals, incompatibility between various materials in terms of physical and chemical properties can lead to reliability issues in electronic products. In particular, the compatibility between flux residues generated after soldering and electronic adhesives often results in corrosion and electromigration of electronic components, as well as incomplete curing of electronic adhesives. Therefore, scientifically and efficiently evaluating the compatibility between soldering materials and electronic adhesives is crucial for ensuring the reliability of electronic products.

[0003] Currently, research on the compatibility of welding materials and electronic adhesives lacks evaluation methods and standards, which cannot provide effective guidance for enterprises to carry out material screening work and makes it difficult to reduce potential product quality hazards caused by compatibility issues. Summary of the Invention

[0004] Therefore, it is necessary to provide a method for evaluating the compatibility of electronic assembly welding materials and electronic adhesives.

[0005] A method for evaluating the compatibility of electronic assembly soldering materials and electronic adhesives includes the following steps:

[0006] A soldering material and an electronic adhesive to be tested are coated on a printed circuit board, and the soldering material and the electronic adhesive are in contact to obtain a test sample.

[0007] The test sample was subjected to temperature cycling environment test and damp heat environment test to obtain the test sample;

[0008] The difference in physicochemical properties of the welding material and the electronic adhesive before and after the test is obtained. The physicochemical properties include at least one of the following: surface appearance, electrical conductivity, organic matrix material composition, thermal decomposition temperature, surface insulation, and appearance at the interface between the welding material and the electronic adhesive.

[0009] The compatibility between the welding material and the electronic adhesive is evaluated based on the differences in their physicochemical properties.

[0010] In one embodiment, the printed circuit board includes at least one of a comb-shaped electrode plate, a daisy-chain test sample plate, and a copper-clad laminate.

[0011] In one embodiment, when coating the welding material to be tested and the electronic adhesive onto the comb-shaped electrode plate, the welding material is first placed in the electrode area of ​​the comb-shaped electrode plate and then reflowed for curing; then the electronic adhesive is coated onto the welding material and cured.

[0012] In one embodiment, when the welding material and electronic adhesive to be tested are coated on the daisy chain test sample, a dummy chip is welded onto the pads of the daisy chain test sample using the welding material; then the electronic adhesive is applied to the gap between the daisy chain test sample and the dummy chip or around the dummy chip and cured.

[0013] In one embodiment, when coating the soldering material and electronic adhesive to be tested onto the copper-clad laminate, the soldering material is first placed on the copper film of the copper-clad laminate and then reflowed and cured; then the electronic adhesive is coated onto the soldering material and cured.

[0014] In one embodiment, the printed circuit board includes the daisy chain test sample, and the physicochemical properties also include dummy on-resistance.

[0015] In one embodiment, the selection of physicochemical property testing items is based on the failure mode of the welding material and the electronic adhesive, wherein the failure mode includes at least one of distortion failure, discoloration failure, deterioration failure, adhesive function failure and insulation function failure.

[0016] When the failure mode includes distortion failure, the inspection items include surface appearance inspection and appearance at the interface between the welding material and the electronic adhesive.

[0017] When the failure mode includes discoloration failure, the inspection items include surface appearance inspection.

[0018] When the failure mode includes degradation failure, the test items include electrical conductivity, organic matrix material composition, and thermal decomposition temperature.

[0019] The failure mode includes failure of the adhesive function, and the inspection items include the appearance at the interface between the welding material and the electronic adhesive.

[0020] The failure mode includes insulation failure, and the inspection items include surface insulation and spurious circuit resistance.

[0021] In one embodiment, the surface appearance inspection includes observing changes in color, cracking, softening, and powdering of the welding material and the electronic adhesive before and after the test.

[0022] In one embodiment, the inspection of the appearance at the interface between the welding material and the electronic adhesive includes: sealing and slicing the test sample, and observing the interface between the welding material and the electronic adhesive using a scanning electron microscope or a metallographic microscope to observe the presence of cracks, delamination, holes, and bubbles.

[0023] In one embodiment, the testing of the organic matrix material composition includes: performing infrared spectroscopy detection on the organic matrix material composition of the electronic adhesive before and after the test, and analyzing the consistency of the number, position, and intensity of peaks of the organic matrix material composition before and after the test.

[0024] In one embodiment, the detection of the thermal decomposition temperature includes: performing thermogravimetric analysis on the electronic adhesive before and after the test to analyze the difference in thermal decomposition temperature before and after the test.

[0025] In one embodiment, the conductivity detection includes: extracting the welding material with pure water, testing the conductivity of the extract, and analyzing the difference in conductivity before and after the test.

[0026] In one embodiment, the surface insulation detection includes: during the damp heat environment test, using an online monitoring system to measure the resistance value of the electronic adhesive, with a test interval of 20 min to 30 min, an applied bias voltage of DC 5V to 50V, and a test voltage of DC 50V to 110V; and checking for corrosion, dendrites, and discoloration of the electrode layer before and after the test.

[0027] In one embodiment, the temperature cycling test includes:

[0028] The test sample was placed in a high-temperature and low-temperature cyclic environment, with a maximum temperature of 80℃~125℃ and a minimum temperature of -55℃ to 400℃. The temperature change rate was 5℃ / min~20℃ / min11℃ / min. The duration of each highest and lowest temperature was 10min~60min, and the number of cycles was 50~1000.

[0029] In one embodiment, the test conditions for the damp heat environment test include:

[0030] The test sample was placed in an environment with a temperature of 65℃~85℃ and a humidity of 40%RH~95%RH for 2h~2000h.

[0031] Compared with traditional methods, the above-mentioned method for evaluating the compatibility of electronic assembly welding materials and electronic adhesives has the following advantages:

[0032] The above evaluation method addresses the compatibility evaluation of soldering materials and electronic adhesives, providing a complete technical solution encompassing "sample preparation, testing, inspection, and evaluation." By subjecting printed circuit boards coated with the soldering materials and electronic adhesives to temperature cycling and damp heat environment tests, the core dimensions and standards for compatibility evaluation of soldering materials and electronic adhesives are clarified. This effectively reduces the risks of short circuits, delamination, and failures in electronic products caused by poor compatibility, thereby lowering product quality risks and rework costs. Attached Figure Description

[0033] Figure 1 The images show the appearance of test samples 3-1 and 3-2 in Example 1 before and after the humid heat environment test; Figure 1 (a) shows the appearance of the sample 3-1 before the humid heat environment test; Figure 1 (b) shows the appearance of the test sample 3-1 after the humid heat environment test; Figure 1 (c) shows the appearance of the sample 3-2 before the humid heat environment test; Figure 1 Image d shows the appearance of sample 3-2 after the humid heat environment test;

[0034] Figure 2 The images show the appearance of test samples 3-1 and 3-2 in Example 1 before and after the temperature cycling test. Figure 2 (a) shows the appearance of the test sample 3-1 before the temperature cycling test; Figure 2 (b) shows the appearance of the test sample 3-1 after the temperature cycling test; Figure 2 Image (c) shows the appearance of sample 3-2 before the temperature cycling test; Figure 2 Image d shows the appearance of sample 3-2 after the temperature cycling test;

[0035] Figure 3 The infrared spectra of the electronic adhesive on the test sample 3-1 in Example 1 before and after the damp heat test and before and after the temperature cycling test are shown. Figure 3 (a) shows the infrared spectra before and after the damp heat test; Figure 3 (b) shows the infrared spectra before and after the temperature cycling test;

[0036] Figure 4 The graphs show the TG curves of the electronic adhesive on the test sample 3-1 in Example 1 before and after the damp heat test and after the temperature cycling test. Figure 4 (a) shows the TG curves before the damp heat test, after 288 hours of the damp heat test, and after 596 hours of the damp heat test. Figure 4 (b) is the TG curve after the temperature cycling test;

[0037] Figure 5The resistance-time curves of the electronic adhesive on the test sample 1-1 in Example 1 during the damp heat test and the temperature cycling test are shown. Figure 5 (a) shows the resistance-time curve in the damp heat test, where 3#1-2, 3#3-4, 3#5-6, and 3#7-8 represent the four electrode circuits connected to the sample 1-1 under test, respectively. Figure 5 (b) shows the resistance-time curve in the temperature cycling test, where 2#1-2, 2#3-4, 2#5-6, and 2#7-8 represent the four electrode circuits connected to the test sample 1-1, respectively.

[0038] Figure 6 The images show SEM images of the interface between the electronic adhesive and the welding material of the test sample 3-2 in Example 1 before the test, after the humid heat environment test, and after the temperature cycling test. Figure 6 (a) is a SEM image of the interface between the electronic adhesive and the soldering material before the experiment; Figure 6 (b) is a SEM image of the interface between the electronic adhesive and the welding material after the humid heat environment test; Figure 6 (c) is a SEM image of the interface between the electronic adhesive and the soldering material after the temperature cycling test. Detailed Implementation

[0039] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein; these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0040] Unless otherwise defined, 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 pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0041] An embodiment of a method for evaluating the compatibility of electronic assembly soldering materials and electronic adhesives includes the following steps:

[0042] Step S1: Coat the soldering material and electronic adhesive to be tested onto the printed circuit board, so that the soldering material and electronic adhesive come into contact to obtain the test sample.

[0043] Step S2: The sample to be tested is subjected to temperature cycling environment test and damp heat environment test to obtain the test sample.

[0044] Step S3: Obtain the differences in physicochemical properties of the welding material and electronic adhesive before and after the test. The physicochemical properties include at least one of the following: surface appearance, electrical conductivity, organic matrix material composition, thermal decomposition temperature, surface insulation, and appearance at the interface between the welding material and the electronic adhesive.

[0045] Step S4: Evaluate the compatibility between the welding material and the electronic adhesive based on the differences in their physicochemical properties.

[0046] The above evaluation method addresses the compatibility evaluation of soldering materials and electronic adhesives, providing a complete technical solution encompassing "sample preparation, testing, inspection, and evaluation." By subjecting printed circuit boards coated with the soldering materials and electronic adhesives to temperature cycling and damp heat environment tests, the core dimensions and standards for compatibility evaluation of soldering materials and electronic adhesives are clarified. This effectively reduces the risks of short circuits, delamination, and failures in electronic products caused by poor compatibility, thereby lowering product quality risks and rework costs.

[0047] Soldering materials refer to the interconnecting and soldering materials involved in the electronic assembly process, including solder paste, solder wire, solder bars, preformed solder pads, flux, etc. Electronic adhesives refer to various adhesive materials involved in the electronic assembly process, including but not limited to underfill adhesives, side fillers, potting compounds, fixing adhesives, and surface mount adhesives.

[0048] In some of these examples, in step S1, the printed circuit board is at least one of a comb electrode board, a daisy chain test sample board, and a copper-clad board.

[0049] In some examples, the comb electrode plate uses a FR-4 epoxy glass substrate, meeting the requirements of IPC-6012 standard. The line spacing of the comb electrode plate is, for example, but not limited to, 0.2 mm to 0.4 mm. In some examples, the line spacing of the comb electrode plate is 0.318 mm.

[0050] In some of these examples, when coating the welding material and electronic adhesive to be tested onto the comb-shaped electrode plate, the welding material is first placed on the electrode area of ​​the comb-shaped electrode plate and then reflowed to cure; then the electronic adhesive is coated onto the welding material and cured.

[0051] In some of these examples, the daisy chain test specimens are made of FR-4 epoxy glass and have pre-set pads that meet the requirements of the IPC-6012 standard.

[0052] In some examples, when applying the soldering material and electronic adhesive to the daisy-chain test sample, dummy chips are soldered onto the pads of the daisy-chain test sample using the soldering material; then, electronic adhesive is applied to the gap between the daisy-chain test sample and the dummy chip, or around the dummy chip, and cured. Preferably, the amount of electronic adhesive applied is controlled to completely cover the interface.

[0053] Among them, counterfeit chips are, for example, BGA counterfeit chips. The counterfeit chip model matches the actual application, such as the counterfeit chip size being 12×12mm, the ball diameter being 0.3mm, and the ball pitch being 0.5mm.

[0054] Before applying electronic adhesive, the soldering quality of the dummy chip should be inspected to ensure there are no cold solder joints or bridging. Additionally, the on-resistance of the dummy chip should be measured using an X-ray inspection instrument. If the initial resistance value is stable, the dummy chip is considered to be functioning normally.

[0055] In some examples, the copper-clad laminate is a single-sided copper-clad laminate made of FR-4 epoxy glass. The size of the copper-clad laminate is, for example, 5cm × 5cm, the size of the surface copper film is, for example, 3cm × 3cm, and the thickness of the copper film is 30μm~50μm, or the same as the copper layer thickness of the actual electronic device.

[0056] In some of these examples, when applying the soldering material and electronic adhesive to be tested to the copper-clad laminate, the soldering material is first placed on the copper film of the copper-clad laminate and reflowed for curing; then the electronic adhesive is applied to the soldering material and cured.

[0057] The coating thickness of the welding material is, for example, 0.5μm to 1μm, specifically 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.90μm, 1μm, etc.

[0058] Temperature cycling tests accelerate the separation of the interface layer between the soldering material and the electronic adhesive through high and low temperature changes, thereby enabling rapid identification of the interface compatibility between the soldering material and the electronic adhesive. For example, if the interface separates after the test, the compatibility is poor; otherwise, the compatibility is good.

[0059] In some of these examples, the temperature cycling test in step S2 includes:

[0060] The test sample was placed in a high-temperature and low-temperature cyclic environment, with a maximum temperature of 80℃~125℃ and a minimum temperature of -55℃~-40℃. The temperature change rate was 5℃ / min~20℃ / min. The duration of each highest and lowest temperature was 10min~60min, and the number of cycles was 50~1000.

[0061] In some of these examples, the temperature cycling test in step S2 includes:

[0062] The test sample was placed in a high-temperature and low-temperature cyclic environment with a maximum temperature of 125℃ and a minimum temperature of -40℃. The temperature change rate was 11℃ / min. The duration of each highest and lowest temperature was 30min, and the number of cycles was 1000.

[0063] Humidity and heat environment testing accelerates the aging of welding materials and electronic adhesives, as well as the penetration of moisture, through the combined effects of high temperature and water vapor, thereby enabling rapid identification of the interface compatibility between the welding materials and electronic adhesives. For example, if the interface separates after the test, the compatibility is poor; conversely, if it remains intact, the compatibility is good.

[0064] In some of these examples, the test conditions for the damp heat environment test in step S2 include:

[0065] The test samples were placed in an environment with a temperature of 65℃~85℃ and a humidity of 40%RH~95%RH for 2h~1000h.

[0066] In some of these examples, the test conditions for the damp heat environment test in step S2 include:

[0067] The test sample was placed in an environment with a temperature of 85℃ and a humidity of 85%RH for 596 hours.

[0068] The resistance value was measured using an online monitoring system with a test interval of 30 minutes, an applied bias voltage of 50VDC, and a test voltage of 110VDC.

[0069] In step S3, the test items are selected based on the failure modes of the welding material and the electronic adhesive. The failure modes include at least one of the following: distortion failure, discoloration failure, degradation failure, adhesive failure, and insulation failure.

[0070] Distortion failure refers to the loss of structural stability in a material's appearance due to excessive deformation.

[0071] Discoloration failure refers to a change in the appearance color or transparency of a material without macroscopic deformation.

[0072] Degradation failure refers to macroscopic changes in properties of materials during long-term storage or service, such as pulverization, embrittlement, hardening, softening, and changes in consistency, which are not visible discoloration but are still perceptible. For example, changes in the composition of electronic adhesives can be classified as degradation failure modes.

[0073] Adhesive failure refers to the detachment of adhesive material from the adherend, resulting in the loss of its adhesive function. Examples include the detachment of underfill adhesive from the chip and the delamination of side fill adhesive from the substrate.

[0074] Insulation function failure means that the electronic adhesive loses its insulation ability, resulting in problems such as breakdown, leakage, and short - circuit of the device.

[0075] When the failure mode includes distortion failure, the inspection items include surface appearance inspection and the appearance at the interface between the welding material and the electronic adhesive.

[0076] When the failure mode includes discoloration failure, the inspection items include surface appearance inspection.

[0077] When the failure mode includes deterioration failure, the inspection items include conductivity, organic matrix material composition, and thermal decomposition temperature.

[0078] When the failure mode includes bonding function failure, the inspection items include the appearance at the interface between the welding material and the electronic adhesive.

[0079] When the failure mode includes insulation function failure, the inspection items include surface insulation and dummy chip conduction resistance.

[0080] In step S3, the surface appearance refers to the appearance of the coated welding material or electronic adhesive on the surface layer of the printed circuit board. The inspection of the surface appearance is carried out by visual inspection or optical microscope. Observe whether there are color changes, cracking, softening, and powdering in the appearance of the welding material and the electronic adhesive before and after the temperature cycle environmental test and the damp heat environmental test. If there are no color changes, cracking, softening, and powdering, the surface appearance inspection item is qualified. Otherwise, it is unqualified.

[0081] In step S3, the inspection method for the organic matrix material composition includes: performing infrared spectrum detection on the organic matrix material composition before and after the temperature cycle environmental test and the damp heat environmental test. The inspection of the organic matrix material composition is carried out, for example, in accordance with the requirements of GB / T6040. If the number of peaks, positions, and intensities of the organic matrix material composition before and after the test are the same, the organic matrix material composition inspection item is qualified. Otherwise, it is unqualified.

[0082] In step S3, the inspection of the thermal decomposition temperature is carried out, for example, in accordance with the requirements of GB / T33047.1. Before and after the temperature cycle environmental test and the damp heat environmental test, if the characteristic temperature change of the thermal decomposition temperature of the electronic adhesive is within the range of ±10°C, the thermal decomposition temperature inspection item is qualified. Otherwise, it is unqualified.

[0083] In step S3, the test of surface insulation includes: online monitoring the resistance value of the test sample for at least 168 h, recording the resistance value, removing the electronic adhesive and welding material after the environmental test, and checking whether there are corrosion, dendrites, and obvious discoloration phenomena on the morphology of the electrode layer such as the comb-shaped electrode. Before and after the temperature cycle environmental test and the damp heat environmental test, if the surface insulation of the welding material electronic adhesive is greater than or equal to 100 MΩ, and there is no corrosion, dendrite, or discoloration on the printed circuit board, the surface insulation test item is qualified. Otherwise, it is unqualified.

[0084] In one of the embodiments, the detection of the conduction resistance of the dummy chip includes: during the temperature cycle test, performing a conduction resistance test on the daisy chain test sample of the welded dummy chip before and after the temperature cycle test, and analyzing the difference between the conduction resistance value after the test and the conduction resistance value before the test. If the change in the conduction resistance of the dummy chip before and after the test is not greater than 5%, the detection item of the conduction resistance of the dummy chip is qualified.

[0085] In step S3, the steps for detecting the appearance at the interface between the welding material and the electronic adhesive include: encapsulating and slicing the test sample, and observing the interface layer between the welding material and the electronic adhesive through a scanning electron microscope or a metallurgical microscope. Before and after the temperature cycle environmental test and the damp heat environmental test, observe whether there are obvious cracks, delamination, holes, bubbles, etc. at the interface between the welding material and the electronic adhesive. If there are no obvious cracks, delamination, holes, bubbles, etc., the appearance detection item at the interface between the welding material and the electronic adhesive is qualified. Otherwise, it is unqualified.

[0086] In step S3, the detection of the conductivity includes: peeling the electronic adhesive, extracting and cleaning the welded material after reflux curing with 10 mL of pure water repeatedly 3 times, and performing a conductivity test on the extracted cleaning solution according to the requirements of GB / T 12582. If the conductivity after the environmental test is less than or equal to 2 times the conductivity before the environmental test, the conductivity detection item is qualified. Otherwise, it is unqualified.

[0087] In some of the examples, in step S3, the physical and chemical properties also include the conduction resistance of the dummy chip. Measure the conduction resistance of the dummy chip before and after the test, and calculate the resistance change rate after the test compared with that before the test. If the resistance change rate of the conduction resistance of the dummy chip is within the range of ±5% of the initial value, the detection item of the conduction resistance of the dummy chip is qualified. Otherwise, it is unqualified.

[0088] In some of the examples, the physical and chemical properties include surface appearance, conductivity, organic matrix material composition, thermal decomposition temperature, surface insulation, and appearance at the interface between the welding material and the electronic adhesive.

[0089] The above evaluation method constructs a multi-dimensional collaborative evaluation technology system for the interfacial compatibility of welding materials and electronic adhesives. In addition to using surface insulation as a basic compatibility evaluation index, it also integrates multi-dimensional testing methods such as material consistency analysis, composition analysis, functional analysis, and structural analysis. Through precise matching of data from each testing item with failure modes, it achieves comprehensive positioning and in-depth analysis of compatibility issues.

[0090] The following specific embodiments further illustrate the present invention. These specific embodiments are provided to better understand the present invention, but are not intended to limit the scope of the invention and do not constitute a limitation on its content or protection.

[0091] Example 1

[0092] The method for evaluating the compatibility of electronic assembly soldering materials and electronic adhesives in this embodiment includes the following steps:

[0093] (1) Preparation of the sample to be tested using comb-shaped electrode plates.

[0094] Solder paste was printed onto a comb-shaped electrode plate and soldered according to the specified reflow profile, resulting in flux residue on the comb-shaped electrode plate. A 1 mm thick layer of side filler was applied to the surface of the flux residue and then UV cured to obtain test sample 1-1 with a solder paste coating thickness of 0.12 mm and test sample 1-2 with a solder paste coating thickness of 0.24 mm. Test samples 1-1 and 1-2 were connected to a high-resistance online monitoring system and subjected to a 596-hour environmental test at 85℃ and 85%RH, with their insulation resistance values ​​monitored in real time.

[0095] (2) Preparation of chrysanthemum chain test sample.

[0096] A dummy BGA chip was soldered to the pads of a daisy-chain test board using solder paste. X-ray inspection and resistance testing confirmed the dummy chip's functionality. Side filler was applied between the dummy chip and the daisy-chain test board and cured, resulting in test boards 2-1, 2-2, 2-3, and 2-4 with solder paste coating thicknesses of 0.12 mm and 0.24 mm respectively. Test boards 2-1, 2-2, 2-3, and 2-4 were connected to a low-resistance online monitoring system and subjected to 1000 temperature cycling cycles between -40℃ and 125℃ at a heating / cooling rate of 11℃ / min and a storage time of 30 min, with real-time monitoring of their resistance values. The daisy-chain test boards were used to verify the on-resistance of the dummy chip.

[0097] (3) Preparation of copper-clad laminate test samples.

[0098] Solder paste was printed onto the copper film of the copper-clad laminate (CCL), and soldering was performed according to the specified reflow profile, resulting in flux residue in the copper film area of ​​the CCL. Side filler was applied to the surface of the flux residue, with the coating thickness controlled at 0.5 mm, and then UV cured to obtain test samples 3-1 with a solder paste coating thickness of 0.12 mm and 3-2 with a solder paste coating thickness of 0.24 mm. These CCL test samples were used for inspection of appearance, organic matrix material composition, thermal decomposition temperature, conductivity, and interface appearance.

[0099] (4) The failure modes of compatibility are shown in Table 1.

[0100] Table 1. Inspection Items and Failure Modes

[0101]

[0102] (5) Temperature cycling environment test and damp heat environment test were conducted on the above-mentioned test samples, as follows:

[0103] Twelve daisy-chain test samples and six copper-clad laminate test samples were placed in a temperature cycling test chamber and subjected to 1000 temperature cycles at a temperature range of -40℃ to 125℃, a heating rate of 11℃ / min, and a storage time of 30min. The daisy-chain test samples were connected to an online monitoring system, and the resistance value was measured once during each high-temperature and low-temperature holding phase. After 1000 temperature cycles, six daisy-chain test samples and three copper-clad laminate test samples were removed for further testing.

[0104] Six copper-clad laminate test samples and twelve comb-shaped electrode board test samples were placed in an environment with an ambient temperature of 85℃ and a humidity of 85% for 596 hours for a damp heat test. The resistance value was measured using an online monitoring system with a test interval of 30 minutes. The applied bias voltage was 50V DC and the test voltage was 110V DC. After 596 hours, three copper-clad laminate test samples were taken out for testing.

[0105] (6) Evaluate the compatibility between the welding materials and the electronic adhesive based on the test results.

[0106] 1. Surface appearance.

[0107] like Figure 1 As shown, after the damp heat test, the appearance of the test sample 3-1 and the test sample 3-2 did not change significantly, but the color changed slightly.

[0108] like Figure 2 As shown, after the temperature cycling test, the appearance of the test sample 3-1 and the test sample 3-2 did not change significantly, but the color changed slightly.

[0109] 2. Testing of the composition of organic matrix materials.

[0110] Infrared spectral analysis was performed on the side filler of the sample 3-1 before and after the damp heat test. For example... Figure 3 As shown in (a), at 1720cm -1 The positions of the ester group peaks differed; the peak intensity at these positions was significantly lower after the damp heat test than before, indicating a decrease in the ester group content of the material. This suggests that the side filler may have undergone ester group hydrolysis under damp heat conditions. The significantly lower peak intensity of the side filler after the test compared to before indicates poor compatibility.

[0111] Infrared spectral analysis was performed on the side filler of the test sample 3-1 before and after the temperature cycling test. For example... Figure 3 As shown in (b), the peak strength of the side filler after the test did not change significantly compared to before the test, indicating good compatibility.

[0112] 3. Thermal decomposition temperature test.

[0113] Thermogravimetric analysis (TG) was performed on the side filler adhesive of the test sample 3-1 before and after the damp heat test. Figure 4 As shown in (a), both the side filler and the sample before and after the test exhibited only one degradation stage. At approximately 150°C, the sample after the damp heat test began to degrade, while the sample before the test showed no premature decomposition. This indicates that the side filler undergoes a certain degree of hydrolysis under damp heat conditions. The difference in thermal degradation temperature between the side filler after the damp heat test and the sample before the test exceeded 10°C, indicating poor compatibility.

[0114] Thermogravimetric analysis was performed on the side filler of the test sample 3-1 before and after the temperature cycling test. For example... Figure 4 As shown in (b), the side filler adhesive exhibited only one degradation stage before and after the test, with no significant changes. This indicates good compatibility.

[0115] 4. Conductivity test.

[0116] The side filler adhesive covering the test sample 3-2 was peeled off. The contact area between the side filler adhesive and the solder paste was extracted and cleaned repeatedly with 10 mL of pure water three times. The conductivity of the extract was measured, which reflects the total ion content in the extract. The conductivity results are shown in Table 2. As can be seen from the results in Table 2, after the damp heat test, the conductivity at the interface was approximately three times that before the test, indicating an increase in ions at the interface between the side filler adhesive and the solder paste during the test. The conductivity after the test being approximately three times that before the test indicates a compatibility problem.

[0117] Table 2 Conductivity Analysis Results

[0118]

[0119] The side filler adhesive covering the test sample 3-2 was peeled off. The contact area between the side filler adhesive and the solder paste was extracted and cleaned with 10 mL of pure water three times. The conductivity of the extract was measured, which reflects the total ion content in the extract. The conductivity results are shown in Table 3. As can be seen from the results in Table 3, after the temperature cycling test, the conductivity at the interface was less than twice that before the test, indicating that no incompatibility issues occurred.

[0120] Table 3 Conductivity Analysis Results

[0121]

[0122] 5. Surface insulation test.

[0123] like Figure 5 As shown in (a), after undergoing a damp heat environment test, the insulation resistance of the tested sample 1-1 decreased for different flux residue levels. During the test, no corrosion, dendrites, or obvious discoloration were observed on the comb-shaped electrode, but a significant decrease in resistance occurred, with the resistance falling below 10 ohms. 8 Ω indicates a compatibility issue.

[0124] like Figure 5 As shown in (b), after undergoing temperature cycling tests, the insulation resistance of sample 1-1 decreased for all different flux residue levels. During the test, no corrosion, dendrites, or obvious discoloration were observed on the comb-shaped electrodes, but a significant decrease in resistance occurred, with the resistance falling below 10 ohms. 8 Ω indicates a compatibility issue.

[0125] 6. Test the conduction resistance of the fake chip.

[0126] Test samples 2-1, 2-2, 2-3, and 2-4 were subjected to 1000 temperature cycling tests. Their on-resistance was measured before and after the tests, and the rate of change in resistance after the tests compared to before the tests was calculated. The results are shown in Table 4. As can be seen from Table 4, the on-resistance of the dummy samples did not exceed ±5% of the initial value after the temperature cycling tests, indicating that no significant compatibility issues occurred after the temperature cycling tests.

[0127] Table 4 Temperature Cycling Resistance Monitoring Results

[0128]

[0129] 7. Interface appearance inspection.

[0130] The test sample 3-2, after undergoing a 596-day damp heat test, was sealed, sliced, and its interface morphology was observed using a scanning electron microscope. No obvious cracks, delamination, pores, or bubbles were observed at the interface before and after the test. (Comparison) Figure 6In (a) and (b), after the damp heat test, obvious voids and delamination appeared at the interface between the solder paste and the side filler, indicating poor compatibility. Figure 6 As shown in (c), after the temperature cycling test, the interface between the solder paste and the side filler was good, with no obvious voids or delamination, indicating that the interface compatibility of the two materials was good.

[0131] In summary, the side filler adhesive and welding materials have poor compatibility under humid and hot conditions, but good compatibility under temperature cycling conditions.

[0132] The above evaluation method has the following effects:

[0133] 1. The above evaluation method fills the gap in the technology and standards for evaluating the compatibility of welding materials and electronic adhesives, provides a precise scientific basis for the screening of electronic assembly materials, effectively reduces reliability problems such as short circuits, delamination, and failures of electronic products caused by poor compatibility, and significantly reduces product quality risks and rework costs.

[0134] 2. The above evaluation method uses multiple types of test plates to match different evaluation needs, achieves precise matching between environmental testing and failure modes, integrates multi-dimensional test items and quantitative evaluation standards, and covers the core correlation dimensions of material microstructure and macro properties.

[0135] 3. Compared with existing technologies, the above evaluation method combines customized environmental testing with multi-dimensional inspection methods, covering aspects such as material consistency, composition, function, and structural analysis. This not only shortens the time for locating compatibility issues, but also eliminates subjective judgment errors through quantitative indicators, thereby improving the accuracy, efficiency, and applicability of the evaluation.

[0136] 4. The above evaluation method supports narrow line width and spacing test boards and low voltage test conditions, which meets the material compatibility evaluation needs of high-density, narrow-pitch, and low-voltage electronic products in fields such as 5G communication, AI, and quantum computing, and breaks through the limitations of existing technology test boards with large line width and spacing and single test voltage.

[0137] 5. The above evaluation method provides a complete technical solution for the entire process of "sample preparation-testing-inspection-evaluation", which can serve as an industry reference standard, guide the development of electronic assembly material compatibility evaluation from experience-based to standardized and systematic, and help improve the overall technical level of the electronic assembly industry.

[0138] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0139] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for evaluating the compatibility of electronic assembly solder materials with electronic adhesives, characterized by, Includes the following steps: A soldering material and an electronic adhesive to be tested are coated on a printed circuit board, and the soldering material and the electronic adhesive are in contact to obtain a test sample. The test sample was subjected to temperature cycling environment test and damp heat environment test to obtain the test sample; The difference in physicochemical properties of the welding material and the electronic adhesive before and after the test is obtained. The physicochemical properties include at least one of the following: surface appearance, electrical conductivity, organic matrix material composition, thermal decomposition temperature, surface insulation, and appearance at the interface between the welding material and the electronic adhesive. The compatibility between the welding material and the electronic adhesive is evaluated based on the differences in their physicochemical properties.

2. The method for evaluating the compatibility of electronic assembly solder material with electronic adhesive according to claim 1, wherein The printed circuit board includes at least one of a comb-shaped electrode plate, a daisy-chain test sample plate, and a copper-clad laminate.

3. The method of claim 2, wherein the electronic assembly is a printed circuit board. It also meets at least one of the following characteristics (1) to (3): (1) When coating the welding material and electronic adhesive to be tested onto the comb-shaped electrode plate, first place the welding material in the electrode area of ​​the comb-shaped electrode plate and reflow to cure; then coat the welding material with electronic adhesive and cure. (2) When coating the daisy chain test sample with the welding material and electronic adhesive to be tested, the welding material is used to weld dummy pieces on the pads of the daisy chain test sample; then the electronic adhesive is applied to the gap between the daisy chain test sample and the dummy piece or around the dummy piece and cured. (3) When coating the welding material and electronic adhesive to be tested on the copper-clad laminate, first place the welding material on the copper film of the copper-clad laminate and reflow to cure; then coat the welding material with electronic adhesive and cure.

4. The method of claim 3, wherein the electronic assembly is a printed circuit board. The printed circuit board includes the daisy chain test sample, and the physicochemical properties also include the dummy circuit resistance.

5. The method for evaluating the compatibility of electronic assembly welding materials and electronic adhesives as described in claim 4, characterized in that, The selection of physicochemical property testing items is based on the failure modes of welding materials and electronic adhesives. The failure modes include at least one of distortion failure, discoloration failure, deterioration failure, adhesive function failure, and insulation function failure. When the failure mode includes distortion failure, the inspection items include surface appearance inspection and appearance at the interface between the welding material and the electronic adhesive. When the failure mode includes discoloration failure, the inspection items include surface appearance inspection. When the failure mode includes degradation failure, the test items include electrical conductivity, organic matrix material composition, and thermal decomposition temperature. The failure mode includes failure of the adhesive function, and the inspection items include the appearance at the interface between the welding material and the electronic adhesive. The failure mode includes insulation failure, and the inspection items include surface insulation and spurious circuit resistance.

6. The method for evaluating the compatibility of electronic assembly welding materials and electronic adhesives as described in any one of claims 1 to 5, characterized in that, It also meets at least one of the following characteristics (1) to (2): (1) The surface appearance inspection includes: observing the appearance of the welding material and the electronic adhesive before and after the test to see if there are any color changes, cracking, softening and powdering; (2) The appearance inspection of the interface between the welding material and the electronic adhesive includes: sealing and slicing the test sample, and observing the interface between the welding material and the electronic adhesive by scanning electron microscope or metallographic microscope to observe the condition of cracks, delamination, holes and bubbles.

7. The method for evaluating the compatibility of electronic assembly welding materials and electronic adhesives as described in any one of claims 1 to 5, characterized in that, It also meets at least one of the following characteristics (1) to (2): (1) The testing of the organic matrix material composition includes: performing infrared spectroscopy detection on the organic matrix material composition of the electronic adhesive before and after the test, and analyzing the consistency of the number, position and intensity of the organic matrix material composition before and after the test; (2) The detection of the thermal decomposition temperature includes: performing thermogravimetric analysis on the electronic adhesive before and after the test, and analyzing the difference in thermal decomposition temperature before and after the test.

8. The method for evaluating the compatibility of electronic assembly welding materials and electronic adhesives as described in any one of claims 1 to 5, characterized in that, It also meets at least one of the following characteristics (1) to (2): (1) The conductivity detection includes: extracting the surface of the welding material with pure water, testing the conductivity of the extract, and analyzing the difference in conductivity before and after the test; (2) The surface insulation test includes: during the damp heat environment test, the resistance value of the electronic adhesive is measured using an online monitoring system. The test time interval is 20 min to 30 min, the applied bias voltage is DC 5V to 50V, and the test voltage is DC 50V to 110V. The electrode layer is checked for corrosion, dendrites, and discoloration before and after the test.

9. The method for evaluating the compatibility of electronic assembly welding materials and electronic adhesives as described in any one of claims 1 to 5, characterized in that, The temperature cycling environment test includes: The test sample was placed in a high-temperature and low-temperature cyclic environment, with a maximum temperature of 80℃~125℃ and a minimum temperature of -55℃~-40℃. The temperature change rate was 5℃ / min~20℃ / min. The duration of each highest and lowest temperature was 10min~60min, and the number of cycles was 50~1000.

10. The method for evaluating the compatibility of electronic assembly welding materials and electronic adhesives as described in any one of claims 1 to 5, characterized in that, The test conditions for the damp heat environment test include: The test sample was placed in an environment with a temperature of 65℃~85℃ and a humidity of 40%RH~95%RH for 2h~1000h.

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