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Method for an apparatus for PCBA warpage measurement and screening

IP.com Disclosure Number: IPCOM000009895D
Publication Date: 2002-Sep-25
Document File: 7 page(s) / 262K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for an apparatus for printed circuit board assembly (PCBA) warpage measurement and screening. Benefits include improved productivity and an improved testing environment.

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Method for an apparatus for PCBA warpage measurement and screening

Disclosed is a method for an apparatus for printed circuit board assembly (PCBA) warpage measurement and screening. Benefits include improved productivity and an improved testing environment.

Background

              Conventionally, high-volume PCBA warpage screening and measurement uses an L-shape long ruler with the PCBA placed on a granite block’s flat surface and supported with pins at four corners (see Figure 1). This approach is not robust for high volume screening/measurement and depends highly on the technicians skill set.

              Other solutions include CMM metrology and View Basic. They take 2-3 hours/PCBA and require a high production skill set combined with high equipment cost to produce accurate results.

General description

              The disclosed method is a PCBA warpage screening and measurement metrology. This method enables warpage measurement to be performed in 3-5 minutes. This method resolves the high volume-screening requirement with good accuracy at low cost.

              The problem of a high-volume warpage screening and measurement for PCBA is addressed with:

•             Through-put time (TPT) of 3-5 minutes/PCBA

•             Maintenance of accurate results at +/-10%

•             Capability to be performed with minimal training

•             Use of a low-cost jig and fixture

Advantages

              The disclosed method provides advantages, including:

•             Improved productivity due to improved

•             Improved testing environment due to a repeatable and reproducible method

•             Improved capability to be carried out by operators with a low skill set

•             Improved cost effectiveness due to low cost jig and fixture

•             Improved cost effectiveness due to eliminating the CMM or View Basic method with expensive equipment

Detailed description

              The disclosed method is a printed circuit board assembly (PCBA) warpage screening and measurement metrology. An aluminum base plate with a flatness of +/0.1 mm is placed on a jig with five support pins with four pins at four corners and one at the center position. Four guide pins are at the center position of four edges (see Figures 2 through 4). 

              Warpage measurement procedures include the following steps (see Figure 5):

1.           Place the PCBA on top of the support and guide pins to ensure center positioning.

2.           Center the PCBA and press corner #1 and corner #2 slightly to ensure that the bottom surface of the PCBA contacts the support pins surface. This procedure forms a reference plane for warpage. A measurement gauge is used to measure the PCBA bottom surface’s height from the aluminum base at corner #3 and corner #4 respectively.

3.           Repeat step 2, except pr...