A method of encapsulating electronic components with a thermoplastic underfill material

Abstract

A method for encapsulating electronic components with thermoplastic underfill material, the thermoplastic underfill material contains an adhesive composition, the adhesive composition includes the following components in parts by weight: polyether polyol 40-60 parts, polyester polyol 5-30 parts, isocyanate 5-30 parts, chain extender 1-10 parts, tackifying resin 1-10 parts, filler 1-5 parts, plasticizer 1-6 parts. The thermoplastic underfill material is placed on the circuit board before the component patch is placed, and the heating during the reflow soldering process of the component is used to fill the thermoplastic underfill film to the bottom of the component. Compared with the previous process, the curing process after dispensing is omitted, the process is optimized, the entire process is simplified, and the production efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of electronic component packaging technology, and particularly relates to a method for packaging large-size electronic components. Background Technology

[0002] With the advent of the information age, the electronics industry has developed rapidly, and the semiconductor packaging market has expanded rapidly. Underfill materials are widely used because they can effectively protect the quality of chip soldering. Underfill materials can fill the bottom of the chip through capillary action, and after heating or cooling, they form a strong filler layer. This reduces the stress impact caused by the difference in thermal expansion coefficients between the chip and the substrate, improves the structural strength and reliability of components, enhances the drop resistance between the chip and the PCBA, and strengthens the reliability of the connection.

[0003] Currently, existing underfill materials are generally liquid underfill adhesives, with epoxy resin as the main component. During application, they are applied to the edges of components using dispensing or spraying equipment. Through the "capillary effect," the adhesive fills the bottom of the component, and then cures under heat, thereby achieving a reinforcing effect and improving the mechanical properties and reliability of electronic products.

[0004] However, the use of liquid underfill adhesive has the following four main drawbacks:

[0005] 1. Equipment: The initial investment and daily maintenance costs of dispensing equipment are high;

[0006] 2. In terms of process: The dispensing process is complex, time-consuming, and inefficient;

[0007] 3. Reworkability: Rework of liquid bottom filler is difficult after curing, with high rework time and cost and high defect rate;

[0008] 4. Storage: Liquid bottom filler adhesive requires refrigeration or freezing, resulting in high storage and transportation costs and a relatively short shelf life. Summary of the Invention

[0009] To address the aforementioned technical problems in the prior art, this invention provides a method for encapsulating electronic components using a thermoplastic underfill material.

[0010] The entire contents of prior application 202110224814.3, entitled "A thermoplastic bottom filler material and its preparation method and application", are incorporated herein by reference.

[0011] The prior application describes an adhesive composition used in the preparation of an adhesive, wherein the adhesive is preferably in the form of a film, and more preferably a thermoplastic underfill film.

[0012] Therefore, the present invention provides a method or application for using the above-mentioned thermoplastic underfill film for electronic component encapsulation.

[0013] A method for packaging electronic components includes the following steps:

[0014] a. Solder paste printing on circuit boards;

[0015] b. Place a thermoplastic underfill film on the circuit board;

[0016] c. Component surface mount installation;

[0017] d. Fixture fixation;

[0018] e. Reflow soldering;

[0019] The thermoplastic underfill film is made from the following adhesive composition, which includes the following components in parts by weight: 40-60 parts of polyether polyol, 5-30 parts of polyester polyol, 5-30 parts of isocyanate, 1-10 parts of chain extender, 1-10 parts of tackifying resin, 1-5 parts of filler, and 1-6 parts of plasticizer.

[0020] According to an embodiment of the present invention, the adhesive composition comprises the following components in parts by weight: 50-60 parts of polyether polyol, 7-25 parts of polyester polyol, 7-25 parts of isocyanate, 1.5-6 parts of chain extender, 3-8 parts of tackifying resin, 1-3 parts of filler, and 3-6 parts of plasticizer.

[0021] The polyether polyol is an olefin oxide polyether polyol, preferably one, two, or more of an olefin oxide polyether polyol using a low molecular weight polyol as an initiator. For example, the low molecular weight polyol may be selected from one, two, or more of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, glycerol, and dipropylene glycol. Exemplarily, the polyether polyol is selected from polypropylene oxide glycol. Polypropylene oxide glycol is prepared using 1,3-propanediol as an initiator.

[0022] The polyether polyols have an average number-average molecular weight of 800-3000 and a functional group count of 2 or 3. For example, polyoxypropylene glycol with propylene glycol as an initiator has an average molecular weight of 2000 and a functionality of 2.

[0023] According to an embodiment of the present invention, the polyether polyol in the adhesive composition is 40 parts, 43 parts, 45 parts, 48 ​​parts, 50 parts, 55 parts, 58 parts, 60 parts by weight, or any value within the range of any two of the above values.

[0024] According to embodiments of the present invention, the polyester polyol is selected from one, two, or more of aromatic polyester polyols, saturated aliphatic polyester polyols, and alkyd polyester polyols. Preferably, the polyester polyol is a mixture of poly(1,6-hexanediol phthalate) diol and poly(1,6-hexanediol adipate) diol.

[0025] According to an embodiment of the present invention, the polyester polyol has an average number-average molecular weight of 500-4000 and 2 or 3 functional groups. Preferably, the polyester polyol has an average number-average molecular weight of 1000-3000 and 2 or 3 functional groups.

[0026] The average number-average molecular weight of the poly(1,6-hexanediol phthalate) diol is 2000, and its functionality is 2; the average number-average molecular weight of the poly(1,6-hexanediol adipate) diol is 2000, and its functionality is 2.

[0027] According to an embodiment of the present invention, the polyester polyol in the adhesive composition is 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 25 parts, 30 parts by weight, or any value within the range of any two of the above values.

[0028] According to an embodiment of the present invention, the isocyanate is an aromatic isocyanate; preferably, the isocyanate is one of diphenylmethane diisocyanate, toluene diisocyanate, and dimethylbiphenyl diisocyanate.

[0029] According to an embodiment of the present invention, the isocyanate in the adhesive composition is 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 25 parts, 30 parts by weight, or any value within the range of any two of the above values.

[0030] According to an embodiment of the present invention, the chain extender is selected from one, two, or three of ethylene glycol, 1,3-propanediol, and 1,4-butanediol.

[0031] According to an embodiment of the present invention, the chain extender in the adhesive composition is 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts by weight, or any value within the range of any two of the above values.

[0032] According to embodiments of the present invention, the tackifying resin is selected from one, two, or more of petroleum resin, rosin resin, acrylic resin, and terpene resin, preferably acrylic resin and / or rosin resin. Preferably, the softening point of the tackifying resin is 80-120°C; more preferably 80-85°C or 90-110°C.

[0033] According to an embodiment of the present invention, the tackifying resin in the adhesive composition is 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts by weight, or any value within the range of any two of the above values.

[0034] According to an embodiment of the present invention, the filler is selected from one, two or more of calcium carbonate, magnesium carbonate, clay, silicon dioxide, barium sulfate, magnesium hydroxide, and aluminum hydroxide. Exemplarily, the filler is magnesium carbonate; preferably, it is magnesium carbonate with a particle size of 0.3-0.4 μm and an oil absorption capacity of 20-30.

[0035] According to an embodiment of the present invention, in the adhesive composition, the filler is in the following weight parts: 1 part, 2 parts, 3 parts, 4 parts, 5 parts, or any value within the range of any two of the above values.

[0036] According to an embodiment of the present invention, the plasticizer is a liquid phosphate ester flame retardant plasticizer, such as one, two or more of trichloropropyl phosphate, diphenylisooctyl phosphate, tricresyl phosphate and tri(2-ethylhexyl) phosphate.

[0037] According to an embodiment of the present invention, the plasticizer in the adhesive composition is 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts by weight, or any value within the range of any two of the above values.

[0038] According to embodiments of the present invention, the adhesive composition may further include other additives. For example, the other additives may be present in parts by weight of 1-5 parts; exemplary examples include 1 part, 2 parts, 3 parts, 4 parts, 5 parts, or any value within the range of any two of the above values.

[0039] According to embodiments of the present invention, the other additives include, but are not limited to, one, two, or more of colorants, flame retardants, heat stabilizers, antioxidants, and lubricants. The colorants, flame retardants, heat stabilizers, antioxidants, and lubricants can be selected from various additives known in the art.

[0040] According to an embodiment of the present invention, the adhesive composition comprises the following components in parts by weight: 40-60 parts of polypropylene glycol, 5-30 parts of a mixture of poly(1,6-hexanediol phthalate) and poly(1,6-hexanediol adipate), 5-30 parts of diphenylmethane diisocyanate, 1-10 parts of 1,3-propanediol, 1-10 parts of rosin resin, 1-5 parts of magnesium carbonate, and 1-5 parts of trichloropropyl phosphate.

[0041] According to an embodiment of the present invention, the sum of the weight parts of the above components is 100 parts.

[0042] According to an embodiment of the present invention, the thickness of the thermoplastic underfill film made from the adhesive composition is 0.03mm-0.90mm, for example 0.05mm-0.6mm, and exemplary thicknesses are 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, and 0.8mm.

[0043] According to an embodiment of the present invention, the preparation process of the thermoplastic underfill film adopts the prepolymer method, the obtained rubber material is extruded and cast into a film, and then die-cut into a film.

[0044] Preferably, the preparation method includes the following steps:

[0045] (1) Mix the polyether polyol, polyester polyol, tackifying resin and isocyanate according to the above weight parts;

[0046] (2) Add the above-mentioned weight parts of chain extender to the substance obtained in step (1) and carry out the reaction;

[0047] (3) Add the above-mentioned parts by weight of filler, plasticizer and other optional additives to the substance obtained in step (2), and react again to obtain the adhesive;

[0048] (4) The adhesive is cast into a film and die-cut to obtain a film.

[0049] According to an embodiment of the present invention, in step (1), the temperature of the reaction is 60-100°C, for example 70-90°C.

[0050] According to an embodiment of the present invention, in step (1), the vacuum degree of the reaction is not lower than -0.095 MPa.

[0051] According to an embodiment of the present invention, in step (1), the reaction time is 1-2 hours, for example 1.2-1.8 hours.

[0052] According to an embodiment of the present invention, in step (2), the temperature of the reaction is 70-110°C, for example 80-100°C.

[0053] According to an embodiment of the present invention, in step (2), the vacuum degree of the reaction is not lower than -0.095 MPa.

[0054] According to an embodiment of the present invention, in step (2), the reaction time is 1-2 hours, for example 1.2-1.8 hours.

[0055] According to an embodiment of the present invention, in step (3), the temperature of the reaction is 150-180°C, for example 160-170°C.

[0056] According to an embodiment of the present invention, in step (3), the vacuum degree of the reaction is not lower than -0.095 MPa.

[0057] According to an embodiment of the present invention, in step (3), the reaction time is 1-2 hours, for example 1.2-1.8 hours.

[0058] According to an exemplary embodiment of the present invention, preferably, the method for preparing the film includes the following steps:

[0059] (1) Add polyether polyol, polyester polyol, tackifying resin and isocyanate into the reactor according to the above weight parts, and react for 1-2 hours at 60-100℃ and vacuum degree not lower than -0.095MPa.

[0060] (2) After step (1) is completed, add the chain extender into the reactor and react for 1-2 hours at 70-110℃ and a vacuum degree of not less than -0.095MPa.

[0061] (3) After step (2) is completed, add filler, plasticizer and other optional additives to the reactor, and continue the reaction for 1-2 hours at 150-180℃ and vacuum degree not lower than -0.095MPa, and then discharge the material.

[0062] (4) The rubber material obtained in step (3) is cast into a film using an extruder and then die-cut to obtain the finished film.

[0063] According to an embodiment of the present invention, the thermoplastic bottom filler film mentioned in step b is a polyurethane film.

[0064] According to an embodiment of the present invention, the length of the circuit board in step a is greater than 3mm and the width is greater than 3mm. Preferably, the length of the circuit board in step a is ≥5mm and the width is ≥5mm.

[0065] According to an embodiment of the present invention, the thermoplastic bottom filler film in step b is in the shape of a "□" or an "L".

[0066] According to an embodiment of the present invention, the component in step c has a length greater than 1 mm and a width greater than 1 mm; preferably, the component in step c has a length greater than 3 mm and a width greater than 3 mm.

[0067] The present invention also provides a component packaging structure, which is obtained by the above-described packaging method.

[0068] The present invention also provides a component comprising the packaging structure of the above-mentioned component.

[0069] The present invention also provides an electronic device comprising the above-described components.

[0070] According to an embodiment of the present invention, the electronic device may be a mobile phone, a tablet computer, a music player, a navigator, etc.

[0071] The beneficial effects of this invention are:

[0072] This invention utilizes a thermoplastic underfill film, which is placed on the circuit board before components are placed. The film is then heated during the reflow soldering process to fill the bottom of the components. Compared to previous processes, this eliminates the need for a curing step after dispensing, optimizing the process, simplifying the entire workflow, and improving production efficiency. The equipment used in this invention is a pick-and-place machine, eliminating the need for dispensing equipment compared to previous processes, thus reducing equipment and labor costs. Furthermore, the thermoplastic underfill film used in this invention can be stored at room temperature, eliminating the low-temperature storage requirements of liquid underfill compared to previous processes, reducing storage and transportation costs. Attached Figure Description

[0073] Figure 1 and Figure 2 This is a schematic diagram of the thermoplastic bottom filler film in the technical solution of the present invention;

[0074] Figure 3 This is a schematic diagram of the component installation process in Embodiment 1 of the present invention;

[0075] Figure 4 This is a schematic diagram of the structure after the components are installed in Embodiment 1 of the present invention;

[0076] Figure 5 This is a schematic diagram of the component installation process in Embodiment 2 of the present invention;

[0077] Figure 6 This is a schematic diagram of the structure after the components are installed in Embodiment 2 of the present invention. Detailed Implementation

[0078] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0079] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0080] Example 1: A thermoplastic underfill film, which is made from the following raw materials by weight:

[0081] 1200g of polyether polyol

[0082] Aromatic polyester polyols 160g

[0083] 100g of saturated aliphatic polyester polyol

[0084] Diphenylmethane diisocyanate 280g

[0085] 140g of tackifying resin

[0086] Chain extender 34g

[0087] 40g of filler

[0088] 120g of plasticizer

[0089] Among them, the polyether polyol is polyoxypropylene glycol with propylene glycol as the initiator, with an average number-average molecular weight of 2000 and a functionality of 2.

[0090] The aromatic polyester polyol is poly(1,6-hexanediol phthalate), with an average number-average molecular weight of 2000 and a functionality of 2.

[0091] The saturated aliphatic polyester polyol is poly(1,6-hexanediol adipate) diol, with an average number-average molecular weight of 2000 and a functionality of 2.

[0092] The tackifying resin is rosin resin, with a softening point of 95-100℃;

[0093] The chain extender is 1,3-propanediol;

[0094] The filler is magnesium carbonate with a particle size of 0.3-0.4 μm and an oil absorption capacity of 20-30.

[0095] The plasticizer is trichloropropyl phosphate;

[0096] The preparation method of this thermoplastic underfill film includes the following steps:

[0097] (1) Add polyether polyol, polyester polyol, tackifying resin and diphenylmethane diisocyanate into the reaction vessel according to the above dosage, and react for 2 hours at 60-70℃ with a vacuum degree not lower than -0.095MPa;

[0098] (2) After step (1) is completed, add the chain extender into the reactor and react for 2 hours at 80-90℃ with a vacuum degree not lower than -0.095MPa;

[0099] (3) After step (2) is completed, add filler and plasticizer to the reactor and continue the reaction for 1 hour at 170-180℃ with a vacuum degree not lower than -0.095MPa, and then discharge the material;

[0100] (4) The rubber material obtained in step (3) is cast into a film using an extruder and then die-cut to obtain the finished film. The thickness of this thermoplastic bottom filler film is 0.03mm-0.90mm, and the film thickness is uniform. The thickness can be changed according to requirements.

[0101] Example 2: A thermoplastic underfill film, which is made from the following raw materials by weight:

[0102] 1200g of polyether polyol

[0103] Aromatic polyester polyol 128g

[0104] 100g of saturated aliphatic polyester polyol

[0105] Diphenylmethane diisocyanate 280g

[0106] 140g of tackifying resin

[0107] Chain extender 34g

[0108] 40g of filler

[0109] 120g of plasticizer

[0110] Among them, the polyether polyol is polyoxypropylene glycol with propylene glycol as the initiator, with an average number-average molecular weight of 2000 and a functionality of 2.

[0111] The aromatic polyester polyol is poly(neoprene phthalate) diol, with an average number-average molecular weight of 1600 and a functionality of 2.

[0112] The saturated aliphatic polyester polyol is poly(1,6-hexanediol adipate) diol, with an average number-average molecular weight of 2000 and a functionality of 2.

[0113] The tackifying resin is an acrylic resin with a softening point of 80-85℃.

[0114] The chain extender is 1,3-propanediol;

[0115] The filler is magnesium carbonate with a particle size of 0.3-0.4 μm and an oil absorption capacity of 20-30.

[0116] The plasticizer is trichloropropyl phosphate;

[0117] The preparation method of this thermoplastic underfill film includes the following steps:

[0118] (1) Add polyether polyol, polyester polyol, tackifying resin and diphenylmethane diisocyanate into the reaction vessel according to the above dosage, and react for 2 hours at 60-70℃ with a vacuum degree not lower than -0.095MPa;

[0119] (2) After step (1) is completed, add the chain extender into the reactor and react for 2 hours at 80-90℃ with a vacuum degree not lower than -0.095MPa;

[0120] (3) After step (2) is completed, add filler and plasticizer to the reactor, and continue to react for 1 hour at 170-180℃ with a vacuum degree not lower than -0.095MPa, and then discharge the material;

[0121] (4) The rubber material obtained in step (3) is cast into a film using an extruder and then die-cut to obtain the finished product. The thickness of the thermoplastic bottom filler film is 0.03mm-0.90mm, and the film thickness is uniform. The thickness can be changed according to requirements.

[0122] Example 3: A thermoplastic underfill film, which is made from the following raw materials by weight:

[0123] 1200g of polyether polyol

[0124] Aromatic polyester polyols 160g

[0125] 100g of saturated aliphatic polyester polyol

[0126] Diphenylmethane diisocyanate 280g

[0127] 140g of tackifying resin

[0128] Chain extender 40g

[0129] 40g of filler

[0130] 120g of plasticizer

[0131] Among them, the polyether polyol is polyoxypropylene glycol with propylene glycol as the initiator, with an average number-average molecular weight of 2000 and a functionality of 2.

[0132] The aromatic polyester polyol is poly(1,6-hexanediol phthalate), with an average number-average molecular weight of 2000 and a functionality of 2.

[0133] The saturated aliphatic polyester polyol is poly(1,6-hexanediol adipate) diol, with an average number-average molecular weight of 2000 and a functionality of 2.

[0134] The tackifying resin is an acrylic resin with a softening point of 80-85℃.

[0135] The chain extender is 1,4-butanediol;

[0136] The filler is magnesium carbonate with a particle size of 0.3-0.4 μm and an oil absorption capacity of 20-30.

[0137] The plasticizer is trichloropropyl phosphate;

[0138] The preparation method of this thermoplastic underfill film includes the following steps:

[0139] (1) Add polyether polyol, polyester polyol, tackifying resin and diphenylmethane diisocyanate into the reaction vessel according to the above dosage, and react for 2 hours at 60-70℃ with a vacuum degree not lower than -0.095MPa;

[0140] (2) After step (1) is completed, add the chain extender into the reactor and react for 2 hours at 80-90℃ with a vacuum degree not lower than -0.095MPa;

[0141] (3) After step (2) is completed, add filler and plasticizer to the reactor, and continue to react for 1 hour at 170-180℃ with a vacuum degree not lower than -0.095MPa, and then discharge the material;

[0142] (4) The rubber material obtained in step (3) is cast into a film using an extruder and then die-cut to obtain the finished product. The thickness of the thermoplastic bottom filler film is 0.03mm-0.90mm, and the film thickness is uniform. The thickness can be changed according to requirements.

[0143] Comparative Example 1: A thermoplastic underfill film made from the following raw materials by weight:

[0144] 1460g of polyether polyol

[0145] Diphenylmethane diisocyanate 280g

[0146] 140g of tackifying resin

[0147] Chain extender 40g

[0148] 40g of filler

[0149] 120g of plasticizer

[0150] Among them, the polyether polyol is polyoxypropylene glycol with propylene glycol as the initiator, with an average number-average molecular weight of 2000 and a functionality of 2.

[0151] The tackifying resin is an acrylic resin with a softening point of 80-85℃.

[0152] The chain extender is 1,4-butanediol;

[0153] The filler is magnesium carbonate with a particle size of 0.3-0.4 μm and an oil absorption capacity of 20-30.

[0154] The plasticizer is trichloropropyl phosphate;

[0155] The preparation method of this thermoplastic underfill film includes the following steps:

[0156] (1) Add polyether polyol, tackifying resin and diphenylmethane diisocyanate into the reaction vessel according to the above dosage, and react for 2 hours at 60-70℃ with a vacuum degree not lower than -0.095MPa;

[0157] (2) After step (1) is completed, add the chain extender into the reactor and react for 2 hours at 80-90℃ with a vacuum degree not lower than -0.095MPa;

[0158] (3) After step (2) is completed, add filler and plasticizer to the reactor, and continue to react for 1 hour at 170-180℃ with a vacuum degree not lower than -0.095MPa, and then discharge the material;

[0159] (4) The rubber material obtained in step (3) is cast into a film using an extruder and then die-cut to obtain the finished product. The thickness of the thermoplastic bottom filler film is 0.03mm-0.90mm, and the film thickness is uniform. The thickness can be changed according to requirements.

[0160] Comparative Example 2: A thermoplastic underfill film made from the following raw materials by weight:

[0161] Aromatic polyester polyols 1460g

[0162] Diphenylmethane diisocyanate 280g

[0163] 140g of tackifying resin

[0164] Chain extender 40g

[0165] 40g of filler

[0166] 120g of plasticizer

[0167] Among them, the aromatic polyester polyol is poly(1,6-hexanediol phthalate), with an average number-average molecular weight of 2000 and a functionality of 2.

[0168] The tackifying resin is an acrylic resin with a softening point of 80-85℃.

[0169] The chain extender is 1,4-butanediol;

[0170] The filler is magnesium carbonate with a particle size of 0.3-0.4 μm and an oil absorption capacity of 20-30.

[0171] The plasticizer is trichloropropyl phosphate;

[0172] The preparation method of this thermoplastic underfill film includes the following steps:

[0173] (1) Add aromatic polyester polyol, tackifying resin and diphenylmethane diisocyanate into the reaction vessel according to the above dosage, and react for 2 hours at 60-70℃ with a vacuum degree not lower than -0.095MPa;

[0174] (2) After step (1) is completed, add the chain extender into the reactor and react for 2 hours at 80-90℃ with a vacuum degree not lower than -0.095MPa;

[0175] (3) After step (2) is completed, add filler and plasticizer to the reactor, and continue to react for 1 hour at 170-180℃ with a vacuum degree not lower than -0.095MPa, and then discharge the material;

[0176] (4) The rubber material obtained in step (3) is cast into a film using an extruder and then die-cut to obtain the finished product. The thickness of the thermoplastic bottom filler film is 0.03mm-0.90mm, and the film thickness is uniform. The thickness can be changed according to requirements.

[0177] Comparative Example 3: A thermoplastic underfill film made from the following raw materials by weight:

[0178] 1200g of polyether polyol

[0179] Aromatic polyester polyols 160g

[0180] 100g of saturated aliphatic polyester polyol

[0181] Diphenylmethane diisocyanate 280g

[0182] Chain extender 40g

[0183] 40g of filler

[0184] Among them, the polyether polyol is polyoxypropylene glycol with propylene glycol as the initiator, with an average number-average molecular weight of 2000 and a functionality of 2.

[0185] The aromatic polyester polyol is poly(1,6-hexanediol phthalate), with an average number-average molecular weight of 2000 and a functionality of 2.

[0186] The saturated aliphatic polyester polyol is poly(1,6-hexanediol adipate) diol, with an average number-average molecular weight of 2000 and a functionality of 2.

[0187] The chain extender is 1,4-butanediol;

[0188] The filler is magnesium carbonate with a particle size of 0.3-0.4 μm and an oil absorption capacity of 20-30.

[0189] The preparation method of this thermoplastic underfill film includes the following steps:

[0190] (1) Add polyether polyol, polyester polyol and diphenylmethane diisocyanate into the reaction vessel according to the above dosage, and react for 2 hours at 60-70℃ with a vacuum degree not lower than -0.095MPa;

[0191] (2) After step (1) is completed, add the chain extender into the reactor and react for 2 hours at 80-90℃ with a vacuum degree not lower than -0.095MPa;

[0192] (3) After step (2) is completed, add packing material to the reactor and continue the reaction for 1 hour at 170-180℃ with a vacuum degree not lower than -0.095MPa, and then discharge the material;

[0193] (4) The rubber material obtained in step (3) is cast into a film using an extruder and then die-cut to obtain the finished product. The thickness of the thermoplastic bottom filler film is 0.03mm-0.90mm, and the film thickness is uniform. The thickness can be changed according to requirements.

[0194] Comparative Example 4: A thermoplastic underfill film made from the following raw materials by weight:

[0195] Aromatic polyester polyols 740g

[0196] 460g of saturated aliphatic polyester polyol

[0197] 260g of polyether polyol

[0198] Diphenylmethane diisocyanate 280g

[0199] 140g of tackifying resin

[0200] Chain extender 34g

[0201] 40g of filler

[0202] 120g of plasticizer

[0203] Among them, the polyether polyol is polyoxypropylene glycol with propylene glycol as the initiator, with an average number-average molecular weight of 2000 and a functionality of 2.

[0204] The aromatic polyester polyol is poly(1,6-hexanediol phthalate), with an average number-average molecular weight of 2000 and a functionality of 2.

[0205] The saturated aliphatic polyester polyol is poly(1,6-hexanediol adipate) diol, with an average number-average molecular weight of 2000 and a functionality of 2.

[0206] The tackifying resin is rosin resin, with a softening point of 95-100℃;

[0207] The chain extender is 1,3-propanediol;

[0208] The filler is magnesium carbonate with a particle size of 0.3-0.4 μm and an oil absorption capacity of 20-30.

[0209] The plasticizer is trichloropropyl phosphate;

[0210] The preparation method of this thermoplastic underfill film includes the following steps:

[0211] (1) Add polyether polyol, polyester polyol, tackifying resin and diphenylmethane diisocyanate into the reaction vessel according to the above dosage, and react for 2 hours at 60-70℃ with a vacuum degree not lower than -0.095MPa;

[0212] (2) After step (1) is completed, add the chain extender into the reactor and react for 2 hours at 80-90℃ with a vacuum degree not lower than -0.095MPa;

[0213] (3) After step (2) is completed, add filler and plasticizer to the reactor and continue the reaction for 1 hour at 170-180℃ with a vacuum degree not lower than -0.095MPa, and then discharge the material;

[0214] (4) The rubber material obtained in step (3) is cast into a film using an extruder and then die-cut to obtain the finished film. The thickness of this thermoplastic bottom filler film is 0.03mm-0.90mm, and the film thickness is uniform. The thickness can be changed according to requirements.

[0215] Test case

[0216] The thermoplastic underfill films prepared in Examples 1-3 and Comparative Examples 1-4 1 Performance tests were conducted, and the results are shown in Table 1.

[0217] Table 1

[0218]

[0219] Note 1: The thickness of the film used in the test was 0.50 mm.

[0220] Note 2: Hydrolysis resistance test method: Cut the film into 100mm*100mm squares, immerse them completely in water of the same temperature and volume, and observe and analyze the changes in the surface and mechanical properties of the samples after immersion for 4 weeks.

[0221] Compared with Comparative Examples 1 and 2, Examples 1, 2 and 3 selected the use of a combination of polyester polyol and polyether polyol, which improved the mechanical properties and bonding strength of the product without affecting its hydrolysis resistance.

[0222] Compared with Comparative Examples 1 and 3, Examples 1, 2 and 3 selected the use of polyester polyol and plasticizer in combination, which improved the flame retardant rating of the product while having a smaller impact on the mechanical properties and viscosity of the product.

[0223] Compared with Comparative Example 3, in Examples 1, 2, and 3, plasticizers and tackifying resins were used, which reduced the viscosity of the products and improved their flowability and bonding strength.

[0224] Compared with Comparative Example 4, in Examples 1, 2, and 3, the blending ratio of polyester polyol and polyether polyol is within the range defined by this invention, resulting in better overall performance.

[0225] In Examples 1, 2, and 3, the products exhibit good fluidity at 200°C, facilitating repairs during use.

[0226] Example 4

[0227] See Figure 1 , 3 As shown in Figure 4, a thermoplastic underfill film for component encapsulation is used in the component encapsulation process. It includes a thermoplastic underfill film 1, a component 3 (chip), solder paste 4, and a circuit board 5. The process includes the following steps:

[0228] a. Solder paste printing on circuit board 5;

[0229] b. The pick-and-place machine places thermoplastic bottom filler film 1 at the corresponding position on the circuit board;

[0230] c. Component surface mount;

[0231] d. Fixture fixation;

[0232] e. Reflow soldering;

[0233] f. Inspect the product.

[0234] In the above process, the thermoplastic underfill film is L-shaped with a thickness of 0.3mm, a length of 6mm, a side height of 0.5mm, and a bottom width of 1mm. This increases the contact area with the components, thereby improving the stability of the thermoplastic underfill film bonding and ensuring the reliability between the components and the circuit board.

[0235] Example 5

[0236] See Figure 2 , 5 As shown in Figure 6, a thermoplastic underfill film for component encapsulation is used in the component encapsulation process. It includes a thermoplastic underfill film 2, a component 3 (chip), solder paste 4, and a circuit board 5. The process includes the following steps:

[0237] g. Solder paste printing on circuit board 5;

[0238] h. The pick and place the thermoplastic bottom filler film 2 at the corresponding position on the circuit board;

[0239] i. Components are surface-mounted (SMD).

[0240] j. Fixture fixing

[0241] k. Reflow soldering;

[0242] l. Product testing.

[0243] In the above process, the thermoplastic filler film is shaped like a "□", with a thickness of 0.5mm, an inner side length of 6mm, and an outer side length of 6.5mm. Its structure can ensure better waterproof, dustproof, and sealing performance at the edges of components.

[0244] Compared with previous processes, the process steps in Examples 4-5 use thermoplastic bottom filler film, which eliminates the dispensing and secondary reflow soldering processes, saving costs and improving efficiency.

[0245] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A packaging method for an electronic component, comprising the following steps: a. Solder paste printing on circuit boards; b. Place a thermoplastic underfill film on the circuit board; c. Component surface mount installation; d. Fixture fixation; e. Reflow soldering; in, The thermoplastic underfill film is made from the following adhesive composition, which consists of the following components in parts by weight: 40-60 parts of polyether polyol, 5-30 parts of polyester polyol, 5-30 parts of isocyanate, 1-10 parts of chain extender, 1-10 parts of tackifying resin, 1-5 parts of filler, and 1-6 parts of plasticizer. The polyether polyol is polyoxypropylene glycol; The polyester polyol is a mixture of poly(1,6-hexanediol phthalate) diol and poly(1,6-hexanediol adipate) diol. The isocyanate is one of diphenylmethane diisocyanate, toluene diisocyanate, and dimethylbiphenyl diisocyanate; The chain extender is selected from one, two, or three of ethylene glycol, 1,3-propanediol, and 1,4-butanediol; The tackifying resin is selected from one, two or more of petroleum resin, rosin resin, acrylic resin and terpene resin; The filler is selected from one, two or more of calcium carbonate, magnesium carbonate, clay, silicon dioxide, barium sulfate, magnesium hydroxide and aluminum hydroxide; The plasticizer is selected from one, two or more of trichloropropyl phosphate, diphenylisooctyl phosphate, tricresyl phosphate and tri(2-ethylhexyl) phosphate.

2. The encapsulation method according to claim 1, wherein the adhesive composition comprises the following components in parts by weight: 40-60 parts of polypropylene glycol, 5-30 parts of a mixture of poly(1,6-hexanediol phthalate) and poly(1,6-hexanediol adipate), 5-30 parts of diphenylmethane diisocyanate, 1-10 parts of 1,3-propanediol, 1-10 parts of rosin resin, 1-5 parts of magnesium carbonate, and 1-5 parts of trichloropropyl phosphate.

3. The encapsulation method according to claim 1, wherein the thickness of the thermoplastic underfill film made from the adhesive composition is 0.03 mm to 0.90 mm.

4. The encapsulation method according to claim 1 or 2, wherein the thermoplastic bottom filler film is prepared by prepolymerization, the obtained adhesive material is extruded and cast into a film, and then die-cut into a film.

5. In the packaging method according to claim 1, the length of the circuit board in step a is greater than 3mm and the width is greater than 3mm.

6. In the encapsulation method according to claim 1, the thermoplastic bottom filler film in step b is in the shape of a "□" or an "L".

7. In the packaging method according to claim 1, the component in step c has a length greater than 1 mm and a width greater than 1 mm.

8. A component packaging structure, which is obtained by the packaging method of any one of claims 1-7.

9. A component comprising the packaging structure of the component of claim 8.

10. An electronic device comprising the components of claim 9.

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