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PCB007-Jan2020

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74 PCB007 MAGAZINE I JANUARY 2020 Sample Plans All sample series plans follow Table E-I from MIL-PRF-31032 C WAM 1, page 49 (Table 1). The sample size is determined from the lot size and the required sample plan series. Note: The lot size is determined by the number of layers/ panels and changes to the number of boards af- ter routing. There are seven sample series in the table. They are labeled B, D, F, H, J, L, and N. For each test or inspection in MIL-PRF-31032, the sample size will be defined either as an exact number or by specifying the test vehicle and a sample plan series from Table E-I. For example, if BL is the required sample plan, B defines the test vehicle as a board, and L defines the sample plan series from Table E-I. Similarly, if the "TN" sample size is required, "T" requires the proper test coupon for the test vehicle, and "N" is the sample plan series. And the use of Table E-I is straightforward. For ex- ample, if the sample series is specified as "TJ" and the lot size is 24, the sample type "T" is a test coupon, and the sample plan series "J" re- quires three test coupons (red items in Table 1). Required testing/inspection can be divided into five main groups: 1. Each lot 2. Each month 3. Each year 4. Every two years 5. Initial qualification (once only) Note: The first four groups are required for continued compliance year after year. 1. Each Lot: Lot Conformance Inspection (LCI) The Inspection points and test performed for samples are listed here: Inner Layer • Develop-etch-strip inspection (DES): "BH" sample plan using the number of layers for lot size (minimum line width and spacing) External Layers • Strip-etch-strip (SES): "BH" sample plan (minimum line width and spacing and plating adhesion) Ionic Contamination Before Solder Mask • One panel per lot Microsection • Structural integrity (per panel, A and B coupons; X and Y direction A coupons plus X and Y direction of B for each hole type [X and Y from opposite corners]) • Solderability (surface): "TJ" sample plan using coupons • Solder mask adhesion: "TJ" sample plan per side using coupons • Marking adhesion: "TJ" sample plan per side using coupons Table 1: Table E-I from MIL-PRF-31032 [1] .

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