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Leadless Multilayer Ceramic Capacitor Stack

A technology of multilayer ceramics and capacitors, applied in stacked capacitors, multiple fixed capacitors, capacitors, etc., can solve the problems of difficult selection of lead frames, damage to MLCC, lack of capacitors, etc.

Active Publication Date: 2017-09-22
KEMET ELECTRONICS CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Leadframe design and material selection can be particularly difficult due to differences in thermal expansion coefficients and the need to minimize equivalent series resistance (ESR), inductance, and other parasitic effects
While it would be desirable to eliminate leadframes, those skilled in the art have not been able to do so, as virtually any board flex would be transferred directly to the MLCC, which would surely damage the MLCC
[0010] Despite ongoing and intensive efforts, there is still a lack of suitable capacitors in the field

Method used

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  • Leadless Multilayer Ceramic Capacitor Stack
  • Leadless Multilayer Ceramic Capacitor Stack
  • Leadless Multilayer Ceramic Capacitor Stack

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0102] Example 1: Improved Mechanical Robustness of Polymer Solders

[0103] 68 identical stacks were fabricated, each with 2 MLCCs, mounted in a common lead frame, and had a case size of 5.6mm x 5.1mm (0.22 x 0.20 inches). These stacks are split into two equal groups of 34 stacks each. One group was a control group in which a lead frame was attached to each MLCC using 1 mg of Sn / Sb solder (with 91.5% Sn and 8.5% Sb by weight). The second group was an inventive group in which the lead frame was attached to each MLCC using 1 mg of Sn / Sb polymer solder (with 91.5% Sn and 8.5% Sb by weight) Available from Henkel as 10048-11A polymer solder. Each component was reflowed three times through a solder reflow oven at 260°C, and the parts were inspected after each pass to determine the number of slumped chips. Results are provided in Table 1, where the cumulative number of failed parts is recorded after each pass.

[0104] Table 1

[0105] Adhesive type

[0106] The resul...

example 2

[0107] Example 2: Mechanical Robustness of Improved TLPS

[0108] A similar stack was made using a silver or tin plated lead frame attached with a copper based instant liquid phase sintering adhesive, for which Ormet 328 may be used. These samples did not exhibit any slumping or detachment of the external leads. A load test was then performed as described in US Patent 6,704,189, in which each stack was placed in a soldering furnace and a 30 g weight was attached to the MLCC and suspended below the stack. The temperature was raised above 260°C in steps of at least 10°C each with a 10 minute hold at each temperature. Each part is then inspected for slump or external lead off failures. The better high temperature mechanical properties of the TLPS are indicated if failures are detected on the silver plated outer leadframe at 360°C and the first failure is detected at 630°C for the tin plated leadframe.

example 3

[0109] EXAMPLE 3: TEMPERATURE PERFORMANCE OF POLYMER SOLDER

[0110] A stack of one hundred and twenty J-leads was fabricated using the same MLCCs, the same J-leads, and a thermocompression bonding process. The samples were divided into several groups, 30 in each group, using different amounts of 91.5 / 8.5Sn / Sb solder (Henkel 92ADA100DAP85V EU 2460 can be selected) for bonding for control samples and polymer solder (Henkel20048-11A can be selected) As a sample of the present invention containing the same solder composition. Subsequently, these samples were passed through several furnaces three times at different temperatures. These samples were then evaluated for part slump. The results are shown in Figure 13 middle. No slumping was detected in the polymer solder samples, indicating improved high temperature robustness in the tested range. Polymer solders will not be able to withstand temperatures above 350°C.

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Abstract

A stacked MLCC capacitor is provided, wherein the capacitor stack includes multilayer ceramic capacitors, each multilayer ceramic capacitor includes a plurality of first electrodes and a plurality of second electrodes stacked alternately, and each first electrode and each a dielectric between adjacent second electrodes. The first electrode terminates on the first side and the second electrode terminates on the second side. A first transient liquid phase sintered conductive layer is on the first side and is in electrical contact with each first electrode; a second transient liquid phase sintered conductive layer is on the second side and is in electrical contact with each second electrode.

Description

technical field [0001] The present invention relates to electronic components and methods of making electronic components. More particularly, the present invention relates to electronic assemblies and methods of making electronic assemblies, particularly stacked leadless multilayer ceramic capacitors having improved terminations for connection to external leads or lead frames, or for use in electronic assemblies A direct leadless connection, whereby the component can then be connected to the electronic circuit through a number of secondary connecting materials and processes. Background technique [0002] In general, the method of forming the conductive terminals and the materials used are very critical to stability. When subsequently installed in an electronic circuit, performance is directly related to the conductive terminals. Previously, lead (Pb) based solders have been used to attach components to electronic circuit boards or to attach external leads to electronic com...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01G4/12H01G4/30
CPCH01G4/30H01G4/12H01G4/38H01G4/232H01G4/2325
Inventor 约翰·E·麦康奈尔约翰·巴尔蒂图德R·艾伦·希尔加里·L·伦纳
Owner KEMET ELECTRONICS CORP