IPCB Naming Convention for Surface Mount Device 3D Models and Footprints. The 3D CAD solid electronic modes/footprint (land pattern) naming. The IPC Land Pattern Viewer is provided on CD-ROM as part of the IPC- Updates to land pattern dimensions, including patterns for new component . IPCB Naming Convention for Standard SMT Land Patterns. Surface Mount Land Patterns. Component, Category. Land Pattern Name.
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While there are many unique components, the Land Pattern Calculator also factors in the many variations of standard components. Leaded ceramic chip carriers are typically supplied with an open cavity for chip placement.
Datum references and position tolerances apply at maximum dimensions, and 3751b dependent on feature size e. The result is the land area available for a solder joint that provides a proper formation of a toe, heel, or side illet.
IPC SMD & PTH Reference Calculators – PCB Libraries Forum – Page 1
Each device family or package type has a standard orientation in relation to ic perforated indexing pattern at the tape edge. Packages may use one or more thermal pads of various sizes.
This package can be either directly mounted to a printed wiring board or used with a socket. Contact pattern is defined when viewed from the bottom. The term diameter of true position 3. Normally a total Z dimension of 7.
In each instance, component manufacturers and board designers are encouraged to either reduce the land size for collapsible solder balls or increase the land size for non-collapsible solder balls by some percentage of the nominal ball 73351b. These additional features become part of the overall land pattern standard for each component type.
IPC-7351 SMD & PTH Reference Calculators
Establishing the maximum outline of the component as measured from lead termination end to lead termination end. Solder mask coatings are available in icp forms, liquid and dry ilm. Designers can use the information contained herein to establish standard land pattern geometries not only for manual designs but also for computer-aided design systems. Solder joint minimums are shown for toe, heel and side fillets.
Without a thermal tab the heel can usually be increased to as much as 0. Position dimensions originate from maximum dimensions f. The TAEC recommends the use of the latest revision. The numbers listed within the tables of IPC are to be used as a guide in determining what the level of producibility will be for any feature. The land pattern libraries included within the IPC LP Calculator provide an analysis of tolerance assumptions and resultant solder joints based on the finished land pattern dimensions.
In instances where shapes are different this becomes a two letter code with the modifier first followed by the land shape letter. Some of the application features that must be considered in selection of a suitable surface finish are given in Table An essential part of the printed board layout is to ensure 77351b the ip of probing points on the printed board is staggered at suficient distances to avoid excessive deformation during multi-probe testing.
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This term can be used in conjunction with other terms listed herein, e. Table through Table indicate the principles used for the three goals established by this standard. Most experts agree that these void conditions, created due to entrapped icp, are acceptable 7531b have no impact on the reliability of the joint.
Vapor phase soldering, also known as condensation soldering, uses the latent heat of vaporization of an inert liquid for soldering.
When plastic array devices are exposed to the environment for an extended period of time, moisture may absorb into the device. The standard gives designers and printed 7351v fabricators updated information on the diverse ipcc of land pattern geometries for all types of active and passive components designed for surface mounting. In addition the size and shape of the proposed land pattern may vary according to the solder mask aperture, the size of the land pattern extension dog bonethe via within the extension, or if the via is in the land pattern itself.
The most common method for solving both outgassing and shadow effect is by switching to the dual wave system where the first wave is turbulent and the second wave is laminar. Y axis CTE, water absorption, to internal layers and cannot process solution entrapment.
The results are more noticeable on fine pitch components. The paste mask on thermal pads is a single square for thermal pads 4. Lead terminations shall be coated with a finish that provides protection and maintains solderablity. All dimensions are in Metric Units 2. Short of having no defects at all, full nodal access remains the most desirable option. Changes to a igure or table are indicated by gray-shading of the igure or table header. The edge of the land associated with the outside of the component body.
The absorbed moisture, if excessive, may expand when exposed to higher temperatures typical of reflow solder processcausing cracking and other physical damage. These tolerances include master pattern accuracy, material movement, layer registration and ixturing. The termination shall be symmetrical, and shall not have nodules, lumps, protrusions, etc.
The second, called the nominal environment, was developed for systems used in controlled environments like offices. In the case of ball grid array BGA packages, the column and row numbers upc given as there are no end termination lead spans.
Two different pin counts are allowed for each package and the component will still meet the standard e.
IPC-7351B Naming Convention for Surface Mount Device 3D Models and Footprints
I have simple a question regarding Chip components and Circular Pads: Special tooling and fixturing holes are generally located within the edge clearance areas. For land pattern designs with routed conductors between lands see Figurethe solder mask pattern must completely cover the conductor. Tube carriers are also used. Also, any via sites that 1.
Typically, the package is supplied with an open cavity for chip attach. The use of inferior laminates can easily lead to problems with lands peeling away during rework. By such action, IPC does not assume any liability to any patent owner, nor do 7351g assume any obligation whatever to parties adopting the Recommended Standard or Publication.