Laser markable molding compound, method of use and device therefrom

• US 4,654,290 A
• Filed: 01/27/1986
• Issued: 03/31/1987
• Est. Priority Date: 02/01/1985
• Status: Expired due to Term

• Current Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Spanjer, Keith G.
• Primary Examiner(s): Kittle, John E.
• Assistant Examiner(s): SHAH, MUKUND JETHALAL
• Application Number:
  US06/822,728
• Time in Patent Office: 428 Days
• Field of Search: 427/53.1, 427/221, 427/213.31, 427/213.36, 264/132, 264/272.17, 264/22, 430/945, 430/138, 29/574, 29/576 T
• US Class Current: 430/138
• CPC Class Codes: B41M 5/267 Marking of plastic artifacts, e.g. with laser
• CPC Class Codes: H01L 2223/54406 comprising alphanumeric information
• CPC Class Codes: H01L 2223/54473 for use after dicing
• CPC Class Codes: H01L 2223/54486 Located on package parts, e.g. encapsulation, leads, package substrate
• CPC Class Codes: H01L 23/544 Marks applied to semiconductor devices or parts, e.g. registration marks, alignment structures, wafer maps test patterns for characterising or monitoring manufacturing processes H01L22/00
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: Y10S 430/146 Laser beam

Abstract

An improved laser markable material useful for encapsulation of electronic devices is obtained by adding TiO₂ or TiO₂ +CrO₃ to common plastic encapsulants formed from a mixture of a resin+filler+carbon black+mold release agent. When irradiated by a laser, the originally grey material turns bright gold, providing a high contrast durable mark. The material has excellent marking contrast as well as better stability with time and temperature as compared to prior art laser markable encapsulants. Desirable concentrations, in weight percent of the compound, are 1-5% TiO₂ and 0-3% CrO₃, with 1-3% TiO₂ and 0.5-2% CrO₃ being preferred. Carbon black is optional but a concentration in the range 0.1-3% by weight is desirable with 0.5-1% preferred. Improved encapsulation and marking methods and improved devices using this material are described.

Claims

1. A device suitable for marking by radiation comprising:

an internal assembly;

covering means coating a portion of said internal assembly, wherein said covering means comprising a compound formed from a plastic resin and a coloring material, wherein said coloring material comprises titanium oxide in the range of 1-5% of the compound by weight.

2. The device of claim 1 wherein said coloring material further comprises 0-3% by weight of chromium oxide.

3. The device of claim 1 wherein said coloring material further comprises carbon black in the range 0.1-3% of the compound by weight.

5. The device of claim 1 wherein said coloring material further comprises 0-3% chromium oxide by weight of said compound.

4. A device suitable for marking by radiation comprising:

an internal assembly;

encapsulation means over a portion of said internal assembly and comprising an exposed compound formed from a plastic resin, a filler material and a coloring material, wherein said coloring material comprises titanium oxide in the range of 1-5% of the compound by weight.

6. The device of claim 4 wherein said filler material comprises silicon oxide or aluminum oxide or a mixture of silicon oxide and aluminum oxide.

7. The device of claim 4 wherein said coloring material further comprises carbon black in the range 0.1-3% by weight of said compound.