Method of forming a package assembly

• US 5,659,950 A
• Filed: 03/23/1995
• Issued: 08/26/1997
• Est. Priority Date: 03/23/1995
• Status: Expired due to Term

• Current Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Dougherty, David J., Adams, Victor J.
• Primary Examiner(s): SOUGH, HYUNG SUB
• Application Number:
  US08/409,130
• Time in Patent Office: 887 Days
• Field of Search: 174/52.1-52.4, 361/764, 361/774, 361/775, 257/731, 257/732, 257/733, 257/666, 257/672, 439/68, 439/70, 437/54, 437/180, 437/211, 437/209, 29/827
• US Class Current: 29/827
• CPC Class Codes: G01P 1/023 for acceleration measuring devices
• CPC Class Codes: H05K 3/306 Lead-in-hole components, e.g. affixing or retention before soldering, spacing means H05K3/32 takes precedence
• CPC Class Codes: H05K 3/308 Adaptations of leads connectors to printed circuits H01R12/00
• CPC Class Codes: Y10T 29/49121 Beam lead frame or beam lead device

Abstract

A method of forming a package assembly (10) including a package (12) that encapsulates an electronic die. A leadframe (30) has edge rails (32), and the die is disposed on the leadframe. The package is formed around the die to encapsulate it, and the leadframe is trimmed to provide a plurality of leads (14) protruding from a first side of the package. This trimming also provides a support (16) connected to a second side of the package. The support is bent to be substantially orthogonal to the common plane containing the leads. A mounting tip (26) on the support is thus disposed outside of the common plane. This support improves the rigidity and natural bending frequency of the package assembly.

Claims

1. A method of forming a package assembly, comprising the steps of:

providing a leadframe having an edge rail;

disposing an accelerometer on said leadframe;

encapsulating said accelerometer within a package formed around both said accelerometer and a portion of said leadframe proximate to said accelerometer;

trimming said leadframe to provide a plurality of leads protruding from a first side of said package and a support connected to a second side of said package, wherein said plurality of leads is electrically coupled to said accelerometer and has a plurality of mounting tips disposed in a substantially common plane and said support is electrically isolated from said accelerometer; and

bending said support so that a mounting tip of said support is disposed substantially outside of said substantially common plane to increase a resonance frequency for said accelerometer to greater than about 2,000 Hz.

2. The method of claim 1 wherein:

said support comprises a flap and a tab, said tab connects said flap to said package, and said tab is substantially in said substantially common plane; and

said flap is disposed substantially orthogonal to said tab after said step of bending.

3. The method of claim 2 wherein said plurality of leads protrudes from only a first side of said package and said tab protrudes from a second side of said package.

4. The method of claim 3 further comprising the step of forming a detent in said mounting tip of said support.

5. The method of claim 3 wherein said step of disposing an accelerometer further comprises disposing a control die on said leadframe proximate to said accelerometer, wherein said control die is electrically coupled to said accelerometer.

6. The method of claim 1 wherein said step of bending said support provides a resonant frequency of said package assembly of about 3,000 Hz.

7. The method of claim 1 wherein said mounting tip is disposed outside of said substantially common plane by a distance of about 2 millimeters.