CN116435193A - Processing technology of conveniently-adjusted lead frame - Google Patents
Processing technology of conveniently-adjusted lead frame Download PDFInfo
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- CN116435193A CN116435193A CN202310466737.1A CN202310466737A CN116435193A CN 116435193 A CN116435193 A CN 116435193A CN 202310466737 A CN202310466737 A CN 202310466737A CN 116435193 A CN116435193 A CN 116435193A
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- material belt
- lead frame
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- silver
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- 239000000463 material Substances 0.000 claims abstract description 122
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 64
- 229910052709 silver Inorganic materials 0.000 claims abstract description 64
- 239000004332 silver Substances 0.000 claims abstract description 64
- 239000010949 copper Substances 0.000 claims abstract description 52
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 51
- 229910052802 copper Inorganic materials 0.000 claims abstract description 51
- 238000005530 etching Methods 0.000 claims abstract description 21
- 239000000243 solution Substances 0.000 claims abstract description 15
- 238000005097 cold rolling Methods 0.000 claims abstract description 14
- 239000006104 solid solution Substances 0.000 claims abstract description 12
- 229910052751 metal Inorganic materials 0.000 claims abstract description 10
- 239000002184 metal Substances 0.000 claims abstract description 10
- 238000005266 casting Methods 0.000 claims abstract description 9
- 230000001965 increasing effect Effects 0.000 claims abstract description 8
- 239000011248 coating agent Substances 0.000 claims abstract description 7
- 238000000576 coating method Methods 0.000 claims abstract description 7
- 238000009713 electroplating Methods 0.000 claims abstract description 7
- 238000012546 transfer Methods 0.000 claims abstract description 7
- 230000007547 defect Effects 0.000 claims abstract description 6
- 238000005098 hot rolling Methods 0.000 claims abstract description 5
- 238000002425 crystallisation Methods 0.000 claims abstract description 4
- 230000008025 crystallization Effects 0.000 claims abstract description 4
- 238000007747 plating Methods 0.000 claims description 57
- 239000010410 layer Substances 0.000 claims description 39
- 238000000034 method Methods 0.000 claims description 36
- 238000004140 cleaning Methods 0.000 claims description 33
- 230000008569 process Effects 0.000 claims description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 21
- 239000002585 base Substances 0.000 claims description 19
- 238000004080 punching Methods 0.000 claims description 18
- 239000007788 liquid Substances 0.000 claims description 16
- 238000005096 rolling process Methods 0.000 claims description 15
- 238000010008 shearing Methods 0.000 claims description 15
- 239000000758 substrate Substances 0.000 claims description 13
- 238000006073 displacement reaction Methods 0.000 claims description 12
- 230000000694 effects Effects 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 238000004806 packaging method and process Methods 0.000 claims description 10
- 239000002253 acid Substances 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 9
- 238000002845 discoloration Methods 0.000 claims description 8
- 238000005238 degreasing Methods 0.000 claims description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 6
- 238000004649 discoloration prevention Methods 0.000 claims description 6
- 238000005192 partition Methods 0.000 claims description 6
- 230000010287 polarization Effects 0.000 claims description 6
- 239000011241 protective layer Substances 0.000 claims description 6
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 claims description 6
- 230000004075 alteration Effects 0.000 claims description 4
- 230000008859 change Effects 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- NNFCIKHAZHQZJG-UHFFFAOYSA-N potassium cyanide Chemical compound [K+].N#[C-] NNFCIKHAZHQZJG-UHFFFAOYSA-N 0.000 claims description 4
- 239000000126 substance Substances 0.000 claims description 4
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 3
- 229910045601 alloy Inorganic materials 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 3
- 239000003795 chemical substances by application Substances 0.000 claims description 3
- 239000012459 cleaning agent Substances 0.000 claims description 3
- 230000000536 complexating effect Effects 0.000 claims description 3
- 230000007797 corrosion Effects 0.000 claims description 3
- 238000005260 corrosion Methods 0.000 claims description 3
- 239000013078 crystal Substances 0.000 claims description 3
- 238000005520 cutting process Methods 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 230000002708 enhancing effect Effects 0.000 claims description 3
- 239000010419 fine particle Substances 0.000 claims description 3
- 239000003292 glue Substances 0.000 claims description 3
- 230000035876 healing Effects 0.000 claims description 3
- 238000000265 homogenisation Methods 0.000 claims description 3
- 230000007246 mechanism Effects 0.000 claims description 3
- 229910044991 metal oxide Inorganic materials 0.000 claims description 3
- 150000004706 metal oxides Chemical class 0.000 claims description 3
- 229920002120 photoresistant polymer Polymers 0.000 claims description 3
- 230000009467 reduction Effects 0.000 claims description 3
- WBHQBSYUUJJSRZ-UHFFFAOYSA-M sodium bisulfate Chemical compound [Na+].OS([O-])(=O)=O WBHQBSYUUJJSRZ-UHFFFAOYSA-M 0.000 claims description 3
- 229910000342 sodium bisulfate Inorganic materials 0.000 claims description 3
- 235000013024 sodium fluoride Nutrition 0.000 claims description 3
- 239000011775 sodium fluoride Substances 0.000 claims description 3
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims description 3
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 claims description 3
- 238000001179 sorption measurement Methods 0.000 claims description 3
- 238000009827 uniform distribution Methods 0.000 claims description 3
- 238000002955 isolation Methods 0.000 claims description 2
- 230000000379 polymerizing effect Effects 0.000 claims description 2
- 238000002791 soaking Methods 0.000 claims description 2
- 238000005538 encapsulation Methods 0.000 abstract description 3
- 238000011161 development Methods 0.000 abstract description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 3
- 239000004033 plastic Substances 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010668 complexation reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 238000012858 packaging process Methods 0.000 description 1
- 230000007420 reactivation Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- LFAGQMCIGQNPJG-UHFFFAOYSA-N silver cyanide Chemical compound [Ag+].N#[C-] LFAGQMCIGQNPJG-UHFFFAOYSA-N 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
- H01L21/4814—Conductive parts
- H01L21/4821—Flat leads, e.g. lead frames with or without insulating supports
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
- H01L21/4814—Conductive parts
- H01L21/4821—Flat leads, e.g. lead frames with or without insulating supports
- H01L21/4828—Etching
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Mechanical Engineering (AREA)
- Electroplating Methods And Accessories (AREA)
Abstract
The invention discloses a processing technology of a conveniently-adjusted lead frame, which comprises the steps of S1-S8, wherein the early stage of fine processing is carried out on a material belt for producing the lead frame, hot rolling is carried out on a metal base material, microscopic cracks heal, casting defects are reduced, a supersaturated solid solution is formed through solution treatment, the high-temperature creep resistance of the base material is guaranteed, cold rolling is carried out, participation stress is eliminated, the condition of wave wrinkling of the material belt is relieved, the material belt is kept straight and has good plate shape, then etching and electroplating treatment are carried out on the material belt, an image transfer film is coated on the surface of the material belt, the film is hardened, the film of a non-photosensitive non-graph part is removed through development treatment, the bonding strength of the coating is increased, a silver electroplated layer with fine crystallization is obtained, the anti-color-changing capability of copper is improved, and the high-quality lead frame can be produced after the high-quality material belt is processed firstly, so that the reliability of an integrated circuit after encapsulation can be further improved.
Description
Technical Field
The invention relates to the technical field of lead frames, in particular to a processing technology of a conveniently-adjustable lead frame.
Background
Lead frame the lead frame is used as the chip carrier of the integrated circuit, is a key structural member for realizing the electric connection between the lead-out end of the internal circuit of the chip and the outer lead by means of bonding materials (gold wires, aluminum wires and copper wires), forms an electric loop, plays the role of a bridge connected with an external lead, and is an important basic material in the electronic information industry because the lead frame is needed in most of semiconductor integrated blocks.
Through searching, the patent with the application number of 201711462894.6 discloses a processing technology of a high-reliability lead frame of a small plastic package integrated circuit, and belongs to the technical field of integrated circuit packaging. The high-reliability lead frame processing technology comprises the steps of firstly carrying out conventional degreasing, activating, neutralizing, copper plating, pre-silver plating, silver plating and silver removing processes on the lead frame, and then carrying out microetching, reactivation, copper surface treatment, anode cleaning, silver surface treatment and silver protection processes on the lead frame after silver removal in sequence. The processing technology of the invention increases the binding force between the plastic package material and the substrate in the packaging process by processing the copper surface and the silver surface on the lead frame, and the integrated circuit is not easy to be layered after being packaged, thereby improving the reliability of the integrated circuit after being packaged; through multiple production line verification, the packaged integrated circuit can pass the primary reliability test by 100%, and can meet the production requirement of the high-reliability integrated circuit.
The above scheme realizes difficult layering after packaging the integrated circuit and improves the reliability of the integrated circuit after packaging through microetching and electroplating the lead frame, but the above scheme lacks the processing of the lead frame base material, and only a high-quality material belt for preparing the lead frame is processed, so that a good lead frame can be produced, and further the reliability of the integrated circuit after packaging can be further improved, therefore, the processing technology of the conveniently-adjusted lead frame is needed.
Disclosure of Invention
The invention aims to provide a processing technology of a conveniently-adjusted lead frame, which is characterized in that a metal substrate is hot rolled to heal microscopic cracks, casting defects are reduced, supersaturated solid solution is formed through solution treatment, high-temperature creep resistance of the substrate is guaranteed, cold rolling is carried out to eliminate participation stress, the situation of wave wrinkling of the material belt is relieved, the material belt is kept straight and has good plate shape, then etching and electroplating treatment are carried out on the material belt, the bonding strength of a plating layer is increased, a fine-crystallized silver electroplated layer is obtained, the anti-discoloration capability of copper is improved, the substrate is started, and after the material belt with high quality is processed, the lead frame with high quality can be produced, and further the reliability of an integrated circuit after encapsulation is further improved, so that the problems in the prior art are solved.
In order to achieve the above purpose, the present invention provides the following technical solutions: a processing technology of a conveniently-adjusted lead frame comprises the following steps:
s1, preparing a material belt: hot rolling the metal base material, crushing coarse grains in a casting state, healing microscopic cracks, and reducing casting defects;
s2, solution treatment: the hot rolled base material is dissolved into alloy elements with obviously reduced solubility along with the temperature reduction through high temperature, and then is rapidly quenched and cooled to form supersaturated solid solution;
s3, cold rolling of a material belt: rolling the base material below the crystallization temperature, enhancing the strength and deformation resistance of the base material, and rolling a material belt meeting the thickness requirement;
s4, shearing a material belt: cutting the material belt into a sheet shape, wherein the length of the cut material belt can be used for processing one or more lead frames;
s5, material belt stamping die: stamping and forming a lead frame substrate;
s6, etching: respectively cleaning, pasting a film, exposing, developing, etching, removing the film and cleaning;
s7, electroplating: comprises the procedures of electrolytic degreasing, acid washing, preplating copper, preplating silver, local silver plating, silver stripping and copper discoloration prevention;
s8, checking, packaging and leaving a warehouse.
Preferably, in S1, the metal substrate is placed in a box-type resistance furnace and heated to 850 ℃, and is kept at the temperature for 1h, and then the temperature is heated to 900 ℃ and is kept at the temperature for 1h, and then the thickness of the substrate is rolled to 2.2-4.5mm by adopting a rolling mill for multiple times.
Preferably, in S2, the heating temperature in the solid solution treatment is 980-1250 ℃, the solid solution time is maintained at 30-90min, so that carbide with fine particles and uniform distribution can be conveniently separated out, meanwhile, the stress generated in cold and hot processing is eliminated, the proper grain size can be obtained, and the high-temperature creep resistance of the base material is ensured.
Preferably, in S3, a multi-roller cold rolling mill is used for rolling the material belt, and in the cold rolling process, a cooling mechanism is used for cooling the material belt in order to overcome severe deformation heat and friction heat of the material belt; in addition, the tension rolling mode is adopted in the cold rolling process to promote the homogenization of extension, eliminate the participation stress, lighten the condition of the corrugated material belt, and keep the material belt straight and in good plate shape.
Preferably, in S4, after the strip is cut into a sheet, the edge of the sheet is trimmed, burrs are removed, and the width tolerance is reduced, so that the sheet is ensured not to generate shearing stress, scratch, distortion and chromatic aberration, that is, the shearing blade, the rubber ring and the spacer ring are correctly configured in the shearing process, and reasonable gap and overlapping amount of the shearing blade are ensured.
Preferably, in S5, a punching machine is used to punch the material belt, an identification hole is punched on the material belt, the outer lead, the positioning hole and the partition wall are pre-punched, the glue punching hole is punched according to the positioning of the positioning hole, and then the inner lead one, the inner lead two and the inner lead three are punched, and meanwhile the positioning hole and the partition wall are finely punched.
Preferably, in S6, firstly, cleaning liquid is used to remove foreign matters on the surface of the material belt, the smoothness of the material belt is ensured, then, a layer of image transfer film is coated on the surface of the material belt, and polymerized under the irradiation of ultraviolet light, a light-receiving part forms a film and hardens to become a corrosion-resistant protective layer, then, the film of an un-photosensitive non-pattern part is removed through development treatment, the pattern part which is hardened by photosensitive is left, photoresist is removed to clean the surface of the material belt, etching liquid is used to corrode the material belt, the part which is not protected by the film is removed, finally, alkali liquor is used to strip off and remove the image transfer film after etching, the material belt after the film removal is soaked in the cleaning agent for 5-10min, and then the material belt is cleaned in clean water, so that the surface of the material belt is ensured to be clean.
Preferably, in S6, the etching solution used in the etching treatment is a mixed aqueous solution of sodium fluoride, sodium persulfate and sodium bisulfate, the concentration is 15-25g/L, and the temperature of the solution is 35-45 ℃.
Preferably, in S7, electrolytic degreasing: removing greasy dirt on the surface of the material belt, improving the oil removal efficiency in a mode of improving the current density, and cleaning by using clear water after oil removal is finished;
acid washing: removing a metal oxide film on the surface of the material belt, increasing the activity of the surface of the material belt, and cleaning with clear water after acid washing with 10% sulfuric acid;
pre-plating copper: plating copper and copper on the surface of the material belt, increasing the bonding strength of the plating layer, providing a clean and strong-activity copper surface for the next silver plating process, and cleaning by using clear water after copper preplating is finished;
pre-silvering: a silver displacement preventing agent with silver salt as a main component is adopted, a compact silver protective layer which is well combined with a copper layer is generated on the copper layer through a displacement preventing liquid, displacement reaction of silver plating liquid is prevented when the silver plating liquid contacts the copper layer and is not electrified, and clean water is used for cleaning after the pre-silver plating is finished;
local silver plating: high-speed low-cyanide plating is adopted, and a silver electroplated layer with fine crystals is obtained under high current density by utilizing good complexing polarization effect of potassium cyanide;
desilvering: removing the thin silver layer leaked outside the silver plating area, avoiding the phenomena of roughness and color change of the silver plating layer, and cleaning by using clear water after the silver removal is completed;
copper discoloration prevention: a thin chemical adsorption film is formed on the surface of copper, so that the anti-discoloration capability of copper is improved, after the anti-discoloration process of copper is finished, clean water is used for cleaning, and drying treatment is immediately carried out after cleaning.
Preferably, in S8, the electroplated and dried lead frame is inspected, and the unqualified product is picked up, and the qualified product is placed in a corresponding packaging box, and the details are registered.
Compared with the prior art, the invention has the beneficial effects that:
the invention carries out hot rolling on a metal base material to heal microscopic cracks, reduces casting defects, forms supersaturated solid solution through solution treatment, ensures high-temperature creep resistance of the base material, eliminates participation stress, lightens the condition of the material belt in the case of crumpling, keeps the material belt straight and has good shape, then carries out etching and electroplating treatment on the material belt to increase the bonding strength of a plating layer, obtains a fine-crystallized silver electroplated layer, improves the anti-discoloration capability of copper, and can produce a high-quality lead frame after processing the high-quality material belt from the base material, thereby further improving the reliability of an integrated circuit after encapsulation.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Description of the embodiments
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, the present invention provides a technical solution: a processing technology of a conveniently-adjusted lead frame comprises the following steps:
s1, preparing a material belt: hot rolling the metal base material, crushing coarse grains in a casting state, healing microscopic cracks, and reducing casting defects;
in S1, a metal substrate is placed in a box-type resistance furnace and heated to 850 ℃, the temperature is kept for 1h, the temperature is further heated to 900 ℃, the temperature is kept for 1h, and then the thickness of the substrate is rolled to 2.2-4.5mm by adopting a rolling mill for multiple times.
S2, solution treatment: the hot rolled base material is dissolved into alloy elements with obviously reduced solubility along with the temperature reduction through high temperature, and then is rapidly quenched and cooled to form supersaturated solid solution;
in S2, the heating temperature in the solid solution treatment is 980-1250 ℃, the solid solution time is maintained at 30-90min, so that carbide with fine particles and uniform distribution can be conveniently separated out, meanwhile, the stress generated in the cold and hot processing process is eliminated, the proper grain size can be obtained, and the high-temperature creep resistance of the base material is ensured.
S3, cold rolling of a material belt: rolling the base material below the crystallization temperature, enhancing the strength and deformation resistance of the base material, and rolling a material belt meeting the thickness requirement;
in S3, rolling the material belt by adopting a multi-roller cold rolling mill, wherein in the cold rolling process, a cooling mechanism is required to cool the material belt in order to overcome severe deformation heat and friction heat of the material belt; in addition, the tension rolling mode is adopted in the cold rolling process to promote the homogenization of extension, eliminate the participation stress, lighten the condition of the corrugated material belt, and keep the material belt straight and in good plate shape.
S4, shearing a material belt: cutting the material belt into a sheet shape, wherein the length of the cut material belt can be used for processing one or more lead frames;
in S4, after the material belt is sheared into a sheet shape, the edge of the sheet material belt is required to be trimmed, burrs are taken out, the width tolerance is reduced, the sheet material belt is ensured not to generate shearing stress, scratch, distortion and chromatic aberration, namely, the shearing blade, the rubber ring and the isolation ring are required to be correctly configured in the shearing process, and reasonable shearing blade gap and overlapping amount are ensured.
S5, material belt stamping die: stamping and forming a lead frame substrate;
in S5, punching the material belt by adopting a punching machine, punching an identification hole on the material belt, pre-punching an outer lead, a positioning hole and a partition wall, punching a glue punching hole according to the positioning of the positioning hole, punching an inner lead I, an inner lead II and an inner lead III, and simultaneously finely punching the positioning hole and the partition wall.
S6, etching: respectively cleaning, pasting a film, exposing, developing, etching, removing the film and cleaning;
in S6, firstly removing foreign matters on the surface of the material belt by using cleaning liquid to ensure the smoothness of the material belt, then coating a layer of image transfer film on the surface of the material belt, polymerizing under the irradiation of ultraviolet light, forming a film and hardening a light-receiving part to become a corrosion-resistant protective layer, then removing the film of an un-photosensitive non-pattern part by developing treatment, leaving the photosensitive hardened pattern part, removing photoresist to clean the surface of the material belt, corroding the material belt by using etching liquid to remove the part which is not covered by the film, finally stripping by using alkali liquor to remove the image transfer film after etching, soaking the material belt after film removal in cleaning agent for 5-10min, and then cleaning in clean water to ensure the surface of the material belt.
In S6, the etching solution adopted in the etching treatment is a mixed aqueous solution of sodium fluoride, sodium persulfate and sodium bisulfate, the concentration is 15-25g/L, and the temperature of the solution is 35-45 ℃.
S7, electroplating: comprises the procedures of electrolytic degreasing, acid washing, preplating copper, preplating silver, local silver plating, silver stripping and copper discoloration prevention;
in S7, electrolytic degreasing: removing greasy dirt on the surface of the material belt, improving the oil removal efficiency in a mode of improving the current density, and cleaning by using clear water after oil removal is finished;
acid washing: removing a metal oxide film on the surface of the material belt, increasing the activity of the surface of the material belt, and cleaning with clear water after acid washing with 10% sulfuric acid;
pre-plating copper: plating copper and copper on the surface of the material belt, increasing the bonding strength of the plating layer, providing a clean and strong-activity copper surface for the next silver plating process, and cleaning by using clear water after copper preplating is finished;
pre-silvering: a silver displacement preventing agent with silver salt as a main component is adopted, a compact silver protective layer which is well combined with a copper layer is generated on the copper layer through a displacement preventing liquid, displacement reaction of silver plating liquid is prevented when the silver plating liquid contacts the copper layer and is not electrified, and clean water is used for cleaning after the pre-silver plating is finished;
because the copper material can quickly undergo chemical displacement reaction when contacting silver plating liquid, the combination of the displacement layer and the copper matrix is loose, the combination strength is reduced, if silver is electroplated on the displacement silver layer, the surface of the plating layer is uneven, silver can grow abnormally, and the whole silver plating layer can generate a plating layer foaming phenomenon in the subsequent chip loading and gold wire welding processes, so that the product is scrapped.
Local silver plating: high-speed low-cyanide plating is adopted, and a silver electroplated layer with fine crystals is obtained under high current density by utilizing good complexing polarization effect of potassium cyanide;
traditional cyanide silver plating mainly uses good complex polarization of potassium cyanide to obtain a finely crystallized electroplated layer, so that the current density used is low, otherwise the strong polarization effect can burn the plated layer. In contrast to the high-speed silver plating, the requirement of obtaining a finely crystallized coating at very high current densities requires reduced complexation and reduced concentration polarization effects, so that the high-speed silver plating solution is a high-temperature formulation with a high silver content and low cyanide.
Desilvering: removing the thin silver layer leaked outside the silver plating area, avoiding the phenomena of roughness and color change of the silver plating layer, and cleaning by using clear water after the silver removal is completed;
copper discoloration prevention: a thin chemical adsorption film is formed on the surface of copper, so that the anti-discoloration capability of copper is improved, after the anti-discoloration process of copper is finished, clean water is used for cleaning, and drying treatment is immediately carried out after cleaning.
(1) In order to ensure good solderability and gold wire bondability, the plating layer is required to have a purity of greater than 99.9% and a thickness of greater than 3.5um. If impurities such as Cu are mixed, cu can be diffused to the surface and oxidized in the heating process of gold wire bonding, so that an oxide film is formed, and the bonding property is reduced.
(2) The brightness of the plating layer is controlled between bright and semi-bright, and is generally controlled between GAMO.6 and 0.8. Too bright, the internal stress, hardness and melting point are all too large, so that the welding performance is affected, and too low the brightness, the coating is loose, the surface is easy to oxidize, and the weldability is greatly reduced.
(3) Whether the plating bond is tight or not severely affects the weld quality. The binding force of the coating is generally checked by a high-temperature method, and the coating is locally baked for 3min at 450 ℃ without peeling, falling off, color change and the like.
(4) The size and position of the plating layer are required. Because Ag is a metal which is easy to cause electromigration, when an Ag leakage layer exists on the side surface of the outer leg, the electromigration of Ag is easy to cause short circuit under the action of high temperature and high humidity and an electric field. Therefore, the Ag plating of the lead frame does not allow for plating leakage to the non-plating areas of the side, back, etc. of the outer leg. If the plating is not performed, the plating is removed by a silver removing process.
S8, checking, packaging and leaving a warehouse.
In S8, inspecting the electroplated and dried lead frame, picking out unqualified products, putting the qualified products into corresponding packaging boxes, and registering details.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (10)
1. A processing technology of a conveniently-adjusted lead frame is characterized in that: the method comprises the following steps:
s1, preparing a material belt: hot rolling the metal base material, crushing coarse grains in a casting state, healing microscopic cracks, and reducing casting defects;
s2, solution treatment: the hot rolled base material is dissolved into alloy elements with obviously reduced solubility along with the temperature reduction through high temperature, and then is rapidly quenched and cooled to form supersaturated solid solution;
s3, cold rolling of a material belt: rolling the base material below the crystallization temperature, enhancing the strength and deformation resistance of the base material, and rolling a material belt meeting the thickness requirement;
s4, shearing a material belt: cutting the material belt into a sheet shape, wherein the length of the cut material belt can be used for processing one or more lead frames;
s5, material belt stamping die: stamping and forming a lead frame substrate;
s6, etching: respectively cleaning, pasting a film, exposing, developing, etching, removing the film and cleaning;
s7, electroplating: comprises the procedures of electrolytic degreasing, acid washing, preplating copper, preplating silver, local silver plating, silver stripping and copper discoloration prevention;
s8, checking, packaging and leaving a warehouse.
2. The process for manufacturing a conveniently adjustable lead frame according to claim 1, wherein: in S1, a metal substrate is placed in a box-type resistance furnace and heated to 850 ℃, the temperature is kept for 1h, the temperature is further heated to 900 ℃, the temperature is kept for 1h, and then the thickness of the substrate is rolled to 2.2-4.5mm by adopting a rolling mill for multiple times.
3. The process for manufacturing a conveniently adjustable lead frame according to claim 1, wherein: in S2, the heating temperature in the solid solution treatment is 980-1250 ℃, the solid solution time is maintained at 30-90min, so that carbide with fine particles and uniform distribution can be conveniently separated out, meanwhile, the stress generated in the cold and hot processing process is eliminated, the proper grain size can be obtained, and the high-temperature creep resistance of the base material is ensured.
4. The process for manufacturing a conveniently adjustable lead frame according to claim 1, wherein: in S3, rolling the material belt by adopting a multi-roller cold rolling mill, wherein in the cold rolling process, a cooling mechanism is required to cool the material belt in order to overcome severe deformation heat and friction heat of the material belt; in addition, the tension rolling mode is adopted in the cold rolling process to promote the homogenization of extension, eliminate the participation stress, lighten the condition of the corrugated material belt, and keep the material belt straight and in good plate shape.
5. The process for manufacturing a conveniently adjustable lead frame according to claim 1, wherein: in S4, after the material belt is sheared into a sheet shape, the edge of the sheet material belt is required to be trimmed, burrs are taken out, the width tolerance is reduced, the sheet material belt is ensured not to generate shearing stress, scratch, distortion and chromatic aberration, namely, the shearing blade, the rubber ring and the isolation ring are required to be correctly configured in the shearing process, and reasonable shearing blade gap and overlapping amount are ensured.
6. The process for manufacturing a conveniently adjustable lead frame according to claim 1, wherein: in S5, punching the material belt by adopting a punching machine, punching an identification hole on the material belt, pre-punching an outer lead, a positioning hole and a partition wall, punching a glue punching hole according to the positioning of the positioning hole, punching an inner lead I, an inner lead II and an inner lead III, and simultaneously finely punching the positioning hole and the partition wall.
7. The process for manufacturing a conveniently adjustable lead frame according to claim 1, wherein: in S6, firstly removing foreign matters on the surface of the material belt by using cleaning liquid to ensure the smoothness of the material belt, then coating a layer of image transfer film on the surface of the material belt, polymerizing under the irradiation of ultraviolet light, forming a film and hardening a light-receiving part to become a corrosion-resistant protective layer, then removing the film of an un-photosensitive non-pattern part by developing treatment, leaving the photosensitive hardened pattern part, removing photoresist to clean the surface of the material belt, corroding the material belt by using etching liquid to remove the part which is not covered by the film, finally stripping by using alkali liquor to remove the image transfer film after etching, soaking the material belt after film removal in cleaning agent for 5-10min, and then cleaning in clean water to ensure the surface of the material belt.
8. The process for manufacturing a conveniently adjustable lead frame according to claim 7, wherein: in S6, the etching solution adopted in the etching treatment is a mixed aqueous solution of sodium fluoride, sodium persulfate and sodium bisulfate, the concentration is 15-25g/L, and the temperature of the solution is 35-45 ℃.
9. The process for manufacturing a conveniently adjustable lead frame according to claim 1, wherein: in S7, electrolytic degreasing: removing greasy dirt on the surface of the material belt, improving the oil removal efficiency in a mode of improving the current density, and cleaning by using clear water after oil removal is finished;
acid washing: removing a metal oxide film on the surface of the material belt, increasing the activity of the surface of the material belt, and cleaning with clear water after acid washing with 10% sulfuric acid;
pre-plating copper: plating copper and copper on the surface of the material belt, increasing the bonding strength of the plating layer, providing a clean and strong-activity copper surface for the next silver plating process, and cleaning by using clear water after copper preplating is finished;
pre-silvering: a silver displacement preventing agent with silver salt as a main component is adopted, a compact silver protective layer which is well combined with a copper layer is generated on the copper layer through a displacement preventing liquid, displacement reaction of silver plating liquid is prevented when the silver plating liquid contacts the copper layer and is not electrified, and clean water is used for cleaning after the pre-silver plating is finished;
local silver plating: high-speed low-cyanide plating is adopted, and a silver electroplated layer with fine crystals is obtained under high current density by utilizing good complexing polarization effect of potassium cyanide;
desilvering: removing the thin silver layer leaked outside the silver plating area, avoiding the phenomena of roughness and color change of the silver plating layer, and cleaning by using clear water after the silver removal is completed;
copper discoloration prevention: a thin chemical adsorption film is formed on the surface of copper, so that the anti-discoloration capability of copper is improved, after the anti-discoloration process of copper is finished, clean water is used for cleaning, and drying treatment is immediately carried out after cleaning.
10. The process for manufacturing a conveniently adjustable lead frame according to claim 1, wherein: in S8, inspecting the electroplated and dried lead frame, picking out unqualified products, putting the qualified products into corresponding packaging boxes, and registering details.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310466737.1A CN116435193A (en) | 2023-04-27 | 2023-04-27 | Processing technology of conveniently-adjusted lead frame |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310466737.1A CN116435193A (en) | 2023-04-27 | 2023-04-27 | Processing technology of conveniently-adjusted lead frame |
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| CN116435193A true CN116435193A (en) | 2023-07-14 |
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|---|---|---|---|
| CN202310466737.1A Pending CN116435193A (en) | 2023-04-27 | 2023-04-27 | Processing technology of conveniently-adjusted lead frame |
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| Country | Link |
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| CN (1) | CN116435193A (en) |
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