Browse Prior Art Database

Self-Centering of Surface Mount Technology Components by Vibration

IP.com Disclosure Number: IPCOM000100688D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 1 page(s) / 33K

Publishing Venue

IBM

Related People

Philip, D: AUTHOR

Abstract

Poor self-centering by slight skewing or misplacement of surface mount technology (SMT) components on a circuit card can have a serious effect on SMT production yields. These problems can be reduced by vibration of the circuit card while solder connecting the components to the circuit card is still molten.

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Self-Centering of Surface

Mount

Technology

Components by Vibration

       Poor self-centering by slight skewing or misplacement of
surface mount technology (SMT) components on a circuit card can have
a serious effect on SMT production yields.  These problems can be
reduced by vibration of the circuit card while solder connecting the
components to the circuit card is still molten.

      During vapor phase soldering of SMT circuit cards, small
outline integrated circuits (SOICs) and chip components (e.g.,
resistors and capacitors) become self-centering as the surface
tension of the molten solder pulls each of the component leads to the
center of its respective pad.  The result is that, within limits,
components which are inaccurately placed on the circuit cards become
aligned during the soldering process.  Large PLCC (Plastic Leaded
Chip Carriers) and SOIC components are too heavy for the passive
surface tension forces to have any significant realignment effect,
and skewed placement is not corrected.  If the skewing is not
corrected during soldering, reworking will be necessary.

      It has been determined that vibration of circuit cards while
being soldered increases the tendency of large components to become
self-centering.  In vapor-phase soldering machines using wire mesh
conveyor belts, vibration of the conveyor belt in a vertical
direction, while it conveys circuit cards with still-molten solder
connections results in centering of the large componen...