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Plated through Hole Internal Connection of Build-Up Circuit Board

IP.com Disclosure Number: IPCOM000112639D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Shirai, M: AUTHOR [+2]

Abstract

This article describes a reliable internal connection method using Plated Through Hole (PTH) in a built-up Surface Laminar Circuit (SLC) board. A plated via is used in combination with an internal conductive land to increase the reliability of the PTH connection.

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This is the abbreviated version, containing approximately 100% of the total text.

Plated through Hole Internal Connection of Build-Up Circuit Board

      This article describes a reliable internal connection method
using Plated Through Hole (PTH) in a built-up Surface Laminar Circuit
(SLC) board.  A plated via is used in combination with an internal
conductive land to increase the reliability of the PTH connection.

      To get higher circuit density, the SLC board uses an internal
circuit layer as thin as 0.01 mm.  On the other hand, a conventional
FR-4 uses 0.035 mm thick copper for the internal circuit.  Cross
sections of the respective plated through holes in SLC and FR-4 are
shown in Fig. 1.  From this Figure, it is seen that the connection
between the PTH and internal circuit of the SLC board is less
reliable than FR-4.

      To improve this internal connection reliability, a via hole 10
is formed at the position of internal land 12 and plated to connect
the lower layer circuit and the upper layer circuit.  So the
conductor thickness at the internal land 12 becomes twice the
thickness of the internal circuit layer.  Thus, when a PTH is drilled
through the plated via conductor 14 and the land 10, the connection
between the internal land and the PTH becomes more reliable.  The
cross section of this improvement is shown in Fig. 2.