Patent US3914858A successfully refreshed from Google Patents.
US3914858A
Expired / Lapsed
US
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Method of making sealed cavity molded semiconductor devices
Assignee: Nitto Denko Corp
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Filing: 1974-08-23
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Granted: 1975-10-28
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Expires: 1994-08-23
Abstract
Abstract A method of making a cavity molded type semiconductor device with an external lead frame is disclosed wherein the external lead frame is prepared with a liquid honing treatment prior to its being molded into a base portion after molding, and after molding, the portion of the lead frame extending into a cavity and the mating surface of the base portion are again subjected to a liquid honing treatment. The two liquid honing treatments serve to markedly increase the ability to prevent leakage of atmospheric air into the sealed cavity of the finished molded semiconductor device.
Inventors
- 👤 Sanenobu Sonoda
- 👤 Masahiro Fujimori
- 👤 Katsumi Yamamoto
- 👤 Seiki Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:39
CPC Classifications
H; H10; H10W; H10W76/00; H10W76/10; H10W76/12; H10W76/15; H10W76/157; H10W76/40; H10W72/00; H10W72/50; H10W72/551; H10W72/552; H10W72/5522; H10W72/5524; H10W74/00; H10W90/00; H10W90/701; H10W90/751; H10W90/756; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49117; Y10T29/49121
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
234 words
A method of making a plastic sealed cavity molded type semiconductor device having a header portion with a cavity therein for mounting a semiconductor device, a lead frame extending through the header portion into the cavity and a cap portion mounted on the header portion to seal the cavity from ambient atmosphere comprising the steps of: a. masking that portion of said lead frame which will extend outside of said header with a masking plate, b. subjecting said masked lead frame to a liquid honing treatment to roughen the surface of the unmasked portions; c. heating the liquid honed lead frame to 80* C.; d. placing the lead frame into a mold and molding the header around a first roughened portion of said lead frame, such that a second roughened portion of the lead frame extends into a cavity in the header; e. subjecting the header and that second roughened portion of the lead frame extending into the cavity to a liquid honing treatment to further roughen the surface of the lead frame and the header surface to which is to be attached a cap portion; f. gold plating that portion of the lead frame extending into the cavity; g. mounting a semiconductor device in the cavity in the header portion; h. connecting internal lead wire between the semiconductor device and the lead frame; and i. mounting the cap portion on the header portion.
Claim 2
Independent Claim
234 words
A method of making a plastic sealed cavity molded type semiconductor device having a header portion with a cavity therein for mounting a semiconductor device, a lead frame extending through the header portion into the cavity and a cap portion mounted on the header portion to seal the cavity from ambient atmosphere comprising the steps of: a. masking that portion of said lead frame which will extend outside of said header with a masking plate, b. subjecting said masked lead frame to a liquid honing treatment to roughen the surface of the unmasked portions; c. heating the liquid honed lead frame to 80* C.; d. placing the lead frame into a mold and molding the header around a first roughened portion of said lead frame, such that a second roughened portion of the lead frame extends into a cavity in the header; e. subjecting the header and that second roughened portion of the lead frame extending into the cavity to a liquid honing treatment to further roughen the surface of the lead frame and the header surface to which is to be attached a cap portion; f. gold plating that portion of the lead frame extending into the cavity; g. mounting a semiconductor device in the cavity in the header portion; h. connecting internal lead wire between the semiconductor device and the lead frame; and i. mounting the cap portion on the header portion.
Claim 3
Dependent Claim
37 words
The method of claim 1 wherein said liquid honing is achieved by subjecting those surfaces to a liquid stream consisting of water and aluminum oxide in a mixture of 2 parts water to 1 part aluminum oxide.
Claim 4
Dependent Claim
20 words
The method of claim 2 wherein the aluminum oxide has a grain size in the range of from 20-30 microns.
Claim 5
Dependent Claim
23 words
The method of claim 2 wherein the liquid honing stream has a flow rate of 1 Sec/cm2 and a pressure of 3 Kg/cm2.
Claim 6
Dependent Claim
25 words
The method of claim 1 wherein the molding of the header portion around the lead frame is accomplished by injection molding an epoxy resin powder.
Claim 7
Dependent Claim
33 words
The method of claim 5 wherein the epoxy resin powder is heated to 150* C. prior to molding, subjected to a pressure of 70 Kg/cm2 and a plunger injection rate of 10 mm/Sec.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |